xxx

.github/workflows/build.yml

@@ -7,10 +7,11 @@ permissions:
   contents: read
 jobs:
   build:
+    if: github.repository == 'PicnicSupermarket/error-prone-support'
     strategy:
       matrix:
         os: [ ubuntu-22.04 ]
-        jdk: [ 17.0.10, 21.0.2, 22.0.2 ]
+        jdk: [ 17.0.10, 21.0.2 ]
         distribution: [ temurin ]
         experimental: [ false ]
         include:
@@ -26,15 +27,13 @@ jobs:
     continue-on-error: ${{ matrix.experimental }}
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@63c24ba6bd7ba022e95695ff85de572c04a18142 # v2.7.0
         with:
           disable-sudo: true
           egress-policy: block
           allowed-endpoints: >
-            api.adoptium.net:443
             github.com:443
             jitpack.io:443
-            objects.githubusercontent.com:443
             repo.maven.apache.org:443
       # We run the build twice for each supported JDK: once against the
       # original Error Prone release, using only Error Prone checks available
@@ -42,7 +41,7 @@ jobs:
       # additionally enabling all checks defined in this project and any Error
       # Prone checks available only from other artifact repositories.
       - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        uses: s4u/setup-maven-action@6d44c18d67d9e1549907b8815efa5e4dada1801b # v1.12.0
         with:
           java-version: ${{ matrix.jdk }}
           java-distribution: ${{ matrix.distribution }}

.github/workflows/codeql.yml

@@ -13,6 +13,7 @@ permissions:
   contents: read
 jobs:
   analyze:
+    if: github.repository == 'PicnicSupermarket/error-prone-support'
     strategy:
       matrix:
         language: [ java, ruby ]
@@ -22,31 +23,30 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@63c24ba6bd7ba022e95695ff85de572c04a18142 # v2.7.0
         with:
           disable-sudo: true
           egress-policy: block
           allowed-endpoints: >
-            api.adoptium.net:443
             api.github.com:443
             github.com:443
             objects.githubusercontent.com:443
             repo.maven.apache.org:443
             uploads.github.com:443
       - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        uses: s4u/setup-maven-action@6d44c18d67d9e1549907b8815efa5e4dada1801b # v1.12.0
         with:
           java-version: 17.0.10
           java-distribution: temurin
           maven-version: 3.9.6
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1
+        uses: github/codeql-action/init@1b1aada464948af03b950897e5eb522f92603cc2 # v3.24.9
         with:
           languages: ${{ matrix.language }}
       - name: Perform minimal build
         if: matrix.language == 'java'
         run: mvn -T1C clean package -DskipTests -Dverification.skip
       - name: Perform CodeQL analysis
-        uses: github/codeql-action/analyze@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1
+        uses: github/codeql-action/analyze@1b1aada464948af03b950897e5eb522f92603cc2 # v3.24.9
         with:
           category: /language:${{ matrix.language }}

.github/workflows/deploy-website.yml

@@ -9,10 +9,11 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
 jobs:
   build:
+    if: github.repository == 'PicnicSupermarket/error-prone-support'
     runs-on: ubuntu-22.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@63c24ba6bd7ba022e95695ff85de572c04a18142 # v2.7.0
         with:
           disable-sudo: true
           egress-policy: block
@@ -39,10 +40,10 @@ jobs:
             www.youtube.com:443
             youtrack.jetbrains.com:443
       - name: Check out code
-        uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4.1.6
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
         with:
           persist-credentials: false
-      - uses: ruby/setup-ruby@6bd3d993c602f6b675728ebaecb2b569ff86e99b # v1.174.0
+      - uses: ruby/setup-ruby@5f19ec79cedfadb78ab837f95b87734d0003c899 # v1.173.0
         with:
           working-directory: ./website
           bundler-cache: true
@@ -74,7 +75,7 @@ jobs:
       url: ${{ steps.deployment.outputs.page_url }}
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@63c24ba6bd7ba022e95695ff85de572c04a18142 # v2.7.0
         with:
           disable-sudo: true
           egress-policy: block

.github/workflows/openssf-scorecard.yml

@@ -14,6 +14,7 @@ permissions:
   contents: read
 jobs:
   analyze:
+    if: github.repository == 'PicnicSupermarket/error-prone-support'
     permissions:
       contents: read
       security-events: write
@@ -21,30 +22,31 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@63c24ba6bd7ba022e95695ff85de572c04a18142 # v2.7.0
         with:
           disable-sudo: true
           egress-policy: block
           allowed-endpoints: >
             api.github.com:443
             api.osv.dev:443
-            api.scorecard.dev:443
             api.securityscorecards.dev:443
+            fulcio.sigstore.dev:443
             github.com:443
             oss-fuzz-build-logs.storage.googleapis.com:443
-            *.sigstore.dev:443
+            rekor.sigstore.dev:443
+            tuf-repo-cdn.sigstore.dev:443
             www.bestpractices.dev:443
       - name: Check out code
-        uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4.1.6
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
         with:
           persist-credentials: false
       - name: Run OpenSSF Scorecard analysis
-        uses: ossf/scorecard-action@dc50aa9510b46c811795eb24b2f1ba02a914e534 # v2.3.3
+        uses: ossf/scorecard-action@0864cf19026789058feabb7e87baa5f140aac736 # v2.3.1
         with:
           results_file: results.sarif
           results_format: sarif
           publish_results: ${{ github.ref == 'refs/heads/master' }}
       - name: Update GitHub's code scanning dashboard
-        uses: github/codeql-action/upload-sarif@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1
+        uses: github/codeql-action/upload-sarif@1b1aada464948af03b950897e5eb522f92603cc2 # v3.24.9
         with:
           sarif_file: results.sarif

.github/workflows/pitest-analyze-pr.yml

@@ -9,20 +9,19 @@ permissions:
   contents: read
 jobs:
   analyze-pr:
+    if: github.repository == 'PicnicSupermarket/error-prone-support'
     runs-on: ubuntu-22.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@63c24ba6bd7ba022e95695ff85de572c04a18142 # v2.7.0
         with:
           disable-sudo: true
           egress-policy: block
           allowed-endpoints: >
-            api.adoptium.net:443
             github.com:443
-            objects.githubusercontent.com:443
             repo.maven.apache.org:443
       - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        uses: s4u/setup-maven-action@6d44c18d67d9e1549907b8815efa5e4dada1801b # v1.12.0
         with:
           checkout-fetch-depth: 2
           java-version: 17.0.10
@@ -38,7 +37,7 @@ jobs:
       - name: Aggregate Pitest reports
         run: mvn pitest-git:aggregate -DkilledEmoji=":tada:" -DmutantEmoji=":zombie:" -DtrailingText="Mutation testing report by [Pitest](https://pitest.org/). Review any surviving mutants by inspecting the line comments under [_Files changed_](${{ github.event.number }}/files)."
       - name: Upload Pitest reports as artifact
-        uses: actions/upload-artifact@65462800fd760344b1a7b4382951275a0abb4808 # v4.3.3
+        uses: actions/upload-artifact@5d5d22a31266ced268874388b861e4b58bb5c2f3 # v4.3.1
         with:
           name: pitest-reports
           path: ./target/pit-reports-ci

.github/workflows/pitest-update-pr.yml

@@ -11,7 +11,7 @@ permissions:
   actions: read
 jobs:
   update-pr:
-    if: ${{ github.event.workflow_run.conclusion == 'success' }}
+    if: ${{ github.event.workflow_run.conclusion == 'success' && github.repository == 'PicnicSupermarket/error-prone-support' }}
     permissions:
       actions: read
       checks: write
@@ -20,18 +20,16 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@63c24ba6bd7ba022e95695ff85de572c04a18142 # v2.7.0
         with:
           disable-sudo: true
           egress-policy: block
           allowed-endpoints: >
-            api.adoptium.net:443
             api.github.com:443
             github.com:443
-            objects.githubusercontent.com:443
             repo.maven.apache.org:443
       - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        uses: s4u/setup-maven-action@6d44c18d67d9e1549907b8815efa5e4dada1801b # v1.12.0
         with:
           java-version: 17.0.10
           java-distribution: temurin

.github/workflows/run-integration-tests.yml

@@ -9,31 +9,29 @@ name: "Integration tests"
 on:
   issue_comment:
     types: [ created ]
+  pull_request:
+  push:
 permissions:
   contents: read
 jobs:
   run-integration-tests:
     name: On-demand integration test
-    if: |
-      github.event.issue.pull_request && contains(github.event.comment.body, '/integration-test')
     runs-on: ubuntu-22.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@63c24ba6bd7ba022e95695ff85de572c04a18142 # v2.7.0
         with:
           disable-sudo: true
           egress-policy: block
           allowed-endpoints: >
-            api.adoptium.net:443
             checkstyle.org:443
             github.com:443
-            objects.githubusercontent.com:443
             oss.sonatype.org:443
             raw.githubusercontent.com:443
             repo.maven.apache.org:443
             repository.sonatype.org:443
       - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        uses: s4u/setup-maven-action@6d44c18d67d9e1549907b8815efa5e4dada1801b # v1.12.0
         with:
           checkout-ref: "refs/pull/${{ github.event.issue.number }}/head"
           java-version: 17.0.10
@@ -45,7 +43,7 @@ jobs:
         run: xvfb-run ./integration-tests/checkstyle.sh "${{ runner.temp }}/artifacts"
       - name: Upload artifacts on failure
         if: ${{ failure() }}
-        uses: actions/upload-artifact@65462800fd760344b1a7b4382951275a0abb4808 # v4.3.3
+        uses: actions/upload-artifact@5d5d22a31266ced268874388b861e4b58bb5c2f3 # v4.3.1
         with:
           name: integration-test-checkstyle
           path: "${{ runner.temp }}/artifacts"

.github/workflows/sonarcloud.yml

@@ -19,23 +19,19 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@63c24ba6bd7ba022e95695ff85de572c04a18142 # v2.7.0
         with:
           disable-sudo: true
           egress-policy: block
           allowed-endpoints: >
-            analysis-sensorcache-eu-central-1-prod.s3.amazonaws.com:443
-            api.adoptium.net:443
-            api.nuget.org:443
             ea6ne4j2sb.execute-api.eu-central-1.amazonaws.com:443
             github.com:443
-            objects.githubusercontent.com:443
             repo.maven.apache.org:443
             sc-cleancode-sensorcache-eu-central-1-prod.s3.amazonaws.com:443
-            *.sonarcloud.io:443
+            scanner.sonarcloud.io:443
             sonarcloud.io:443
       - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        uses: s4u/setup-maven-action@6d44c18d67d9e1549907b8815efa5e4dada1801b # v1.12.0
         with:
           checkout-fetch-depth: 0
           java-version: 17.0.10

.renovaterc.json

@@ -12,7 +12,7 @@
       "separateMinorPatch": true
     },
     {
-      "matchPackageNames": [
+      "matchDepNames": [
         "dawidd6/action-download-artifact",
         "github/codeql-action",
         "ruby/setup-ruby"

documentation-support/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.18.0</version>
+        <version>0.16.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>documentation-support</artifactId>

error-prone-contrib/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.18.0</version>
+        <version>0.16.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-contrib</artifactId>
@@ -122,11 +122,6 @@
             <artifactId>jakarta.servlet-api</artifactId>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>javax.annotation</groupId>
-            <artifactId>javax.annotation-api</artifactId>
-            <scope>provided</scope>
-        </dependency>
         <dependency>
             <groupId>javax.inject</groupId>
             <artifactId>javax.inject</artifactId>

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/JUnitValueSource.java

@@ -232,7 +232,7 @@ public final class JUnitValueSource extends BugChecker implements MethodTreeMatc
       @Override
       public @Nullable Void visitReturn(ReturnTree node, @Nullable Void unused) {
         returnExpressions.add(node.getExpression());
-        return super.visitReturn(node, null);
+        return super.visitReturn(node, unused);
       }
 
       @Override

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationAttributeListing.java

@@ -192,7 +192,7 @@ public final class LexicographicalAnnotationAttributeListing extends BugChecker
       @Override
       public @Nullable Void visitIdentifier(IdentifierTree node, @Nullable Void unused) {
         nodes.add(ImmutableList.of(node.getName().toString()));
-        return super.visitIdentifier(node, null);
+        return super.visitIdentifier(node, unused);
       }
 
       @Override
@@ -203,13 +203,13 @@ public final class LexicographicalAnnotationAttributeListing extends BugChecker
                 ? STRING_ARGUMENT_SPLITTER.splitToStream(str).collect(toImmutableList())
                 : ImmutableList.of(String.valueOf(value)));
 
-        return super.visitLiteral(node, null);
+        return super.visitLiteral(node, unused);
       }
 
       @Override
       public @Nullable Void visitPrimitiveType(PrimitiveTypeTree node, @Nullable Void unused) {
         nodes.add(ImmutableList.of(node.getPrimitiveTypeKind().toString()));
-        return super.visitPrimitiveType(node, null);
+        return super.visitPrimitiveType(node, unused);
       }
     }.scan(array, null);
 

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NonStaticImport.java

@@ -210,7 +210,7 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
           }
         }
 
-        return super.visitIdentifier(node, null);
+        return super.visitIdentifier(node, unused);
       }
     }.scan(tree, null);
   }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ClassRules.java

@@ -3,7 +3,6 @@ package tech.picnic.errorprone.refasterrules;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
-import java.util.function.Function;
 import java.util.function.Predicate;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
@@ -38,12 +37,7 @@ final class ClassRules {
     }
   }
 
-  /**
-   * Prefer {@link Class#isInstance(Object)} method references over lambda expressions that require
-   * naming a variable.
-   */
-  // XXX: Once the `ClassReferenceIsInstancePredicate` rule is dropped, rename this rule to just
-  // `ClassIsInstancePredicate`.
+  /** Prefer {@link Class#isInstance(Object)} method references over more verbose alternatives. */
   static final class ClassLiteralIsInstancePredicate<T, S> {
     @BeforeTemplate
     Predicate<S> before() {
@@ -56,11 +50,7 @@ final class ClassRules {
     }
   }
 
-  /**
-   * Prefer {@link Class#isInstance(Object)} method references over lambda expressions that require
-   * naming a variable.
-   */
-  // XXX: Drop this rule once the `MethodReferenceUsage` rule is enabled by default.
+  /** Prefer {@link Class#isInstance(Object)} method references over more verbose alternatives. */
   static final class ClassReferenceIsInstancePredicate<T, S> {
     @BeforeTemplate
     Predicate<S> before(Class<T> clazz) {
@@ -72,39 +62,4 @@ final class ClassRules {
       return clazz::isInstance;
     }
   }
-
-  /**
-   * Prefer {@link Class#cast(Object)} method references over lambda expressions that require naming
-   * a variable.
-   */
-  // XXX: Once the `ClassReferenceCast` rule is dropped, rename this rule to just `ClassCast`.
-  static final class ClassLiteralCast<T, S> {
-    @BeforeTemplate
-    @SuppressWarnings("unchecked")
-    Function<T, S> before() {
-      return t -> (S) t;
-    }
-
-    @AfterTemplate
-    Function<T, S> after() {
-      return Refaster.<S>clazz()::cast;
-    }
-  }
-
-  /**
-   * Prefer {@link Class#cast(Object)} method references over lambda expressions that require naming
-   * a variable.
-   */
-  // XXX: Drop this rule once the `MethodReferenceUsage` rule is enabled by default.
-  static final class ClassReferenceCast<T, S> {
-    @BeforeTemplate
-    Function<T, S> before(Class<? extends S> clazz) {
-      return o -> clazz.cast(o);
-    }
-
-    @AfterTemplate
-    Function<T, S> after(Class<? extends S> clazz) {
-      return clazz::cast;
-    }
-  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/CollectionRules.java

@@ -8,9 +8,7 @@ import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.AlsoNegation;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
-import com.google.errorprone.refaster.annotation.NotMatches;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
@@ -23,7 +21,6 @@ import java.util.function.Consumer;
 import java.util.function.IntFunction;
 import java.util.stream.Stream;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
-import tech.picnic.errorprone.refaster.matchers.IsRefasterAsVarargs;
 
 /** Refaster rules related to expressions dealing with (arbitrary) collections. */
 // XXX: There are other Guava `Iterables` methods that should not be called if the input is known to
@@ -187,24 +184,6 @@ final class CollectionRules {
     }
   }
 
-  /** Don't unnecessarily call {@link Stream#distinct()} on an already-unique stream of elements. */
-  // XXX: This rule assumes that the `Set` relies on `Object#equals`, rather than a custom
-  // equivalence relation.
-  // XXX: Expressions that drop or reorder elements from the stream, such as `.filter`, `.skip` and
-  // `sorted`, can similarly be simplified. Covering all cases is better done using an Error Prone
-  // check.
-  static final class SetStream<T> {
-    @BeforeTemplate
-    Stream<?> before(Set<T> set) {
-      return set.stream().distinct();
-    }
-
-    @AfterTemplate
-    Stream<?> after(Set<T> set) {
-      return set.stream();
-    }
-  }
-
   /** Prefer {@link ArrayList#ArrayList(Collection)} over the Guava alternative. */
   @SuppressWarnings(
       "NonApiType" /* Matching against `List` would unnecessarily constrain the rule. */)
@@ -297,23 +276,6 @@ final class CollectionRules {
     }
   }
 
-  /** Prefer {@link Arrays#asList(Object[])} over more contrived alternatives. */
-  // XXX: Consider moving this rule to `ImmutableListRules` and having it suggest
-  // `ImmutableList#copyOf`. That would retain immutability, at the cost of no longer handling
-  // `null`s.
-  static final class ArraysAsList<T> {
-    // XXX: This expression produces an unmodifiable list, while the alternative doesn't.
-    @BeforeTemplate
-    List<T> before(@NotMatches(IsRefasterAsVarargs.class) T[] array) {
-      return Arrays.stream(array).toList();
-    }
-
-    @AfterTemplate
-    List<T> after(T[] array) {
-      return Arrays.asList(array);
-    }
-  }
-
   /** Prefer calling {@link Collection#toArray()} over more contrived alternatives. */
   static final class CollectionToArray<T> {
     @BeforeTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ComparatorRules.java

@@ -290,7 +290,7 @@ final class ComparatorRules {
   static final class MinOfPairCustomOrder<T> {
     @BeforeTemplate
     @SuppressWarnings("java:S1067" /* The conditional operators are independent. */)
-    T before(T value1, T value2, Comparator<? super T> cmp) {
+    T before(T value1, T value2, Comparator<T> cmp) {
       return Refaster.anyOf(
           cmp.compare(value1, value2) <= 0 ? value1 : value2,
           cmp.compare(value1, value2) > 0 ? value2 : value1,
@@ -305,7 +305,7 @@ final class ComparatorRules {
     }
 
     @AfterTemplate
-    T after(T value1, T value2, Comparator<? super T> cmp) {
+    T after(T value1, T value2, Comparator<T> cmp) {
       return Comparators.min(value1, value2, cmp);
     }
   }
@@ -357,7 +357,7 @@ final class ComparatorRules {
   static final class MaxOfPairCustomOrder<T> {
     @BeforeTemplate
     @SuppressWarnings("java:S1067" /* The conditional operators are independent. */)
-    T before(T value1, T value2, Comparator<? super T> cmp) {
+    T before(T value1, T value2, Comparator<T> cmp) {
       return Refaster.anyOf(
           cmp.compare(value1, value2) >= 0 ? value1 : value2,
           cmp.compare(value1, value2) < 0 ? value2 : value1,
@@ -372,7 +372,7 @@ final class ComparatorRules {
     }
 
     @AfterTemplate
-    T after(T value1, T value2, Comparator<? super T> cmp) {
+    T after(T value1, T value2, Comparator<T> cmp) {
       return Comparators.max(value1, value2, cmp);
     }
   }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/EqualityRules.java

@@ -1,6 +1,5 @@
 package tech.picnic.errorprone.refasterrules;
 
-import static java.util.function.Predicate.isEqual;
 import static java.util.function.Predicate.not;
 
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
@@ -20,9 +19,9 @@ import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 final class EqualityRules {
   private EqualityRules() {}
 
-  /** Prefer reference-based equality for enums. */
-  // Primitive value comparisons are not matched, because Error Prone flags those out of the box.
-  static final class EnumReferenceEquality<T extends Enum<T>> {
+  /** Prefer reference-based quality for enums. */
+  // Primitive value comparisons are not listed, because Error Prone flags those out of the box.
+  static final class PrimitiveOrReferenceEquality<T extends Enum<T>> {
     /**
      * Enums can be compared by reference. It is safe to do so even in the face of refactorings,
      * because if the type is ever converted to a non-enum, then Error-Prone will complain about any
@@ -44,20 +43,6 @@ final class EqualityRules {
     }
   }
 
-  /** Prefer reference-based equality for enums. */
-  static final class EnumReferenceEqualityLambda<T extends Enum<T>> {
-    @BeforeTemplate
-    Predicate<T> before(T e) {
-      return Refaster.anyOf(isEqual(e), e::equals);
-    }
-
-    @AfterTemplate
-    @SuppressWarnings("java:S1698" /* Reference comparison is valid for enums. */)
-    Predicate<T> after(T e) {
-      return v -> v == e;
-    }
-  }
-
   /** Prefer {@link Object#equals(Object)} over the equivalent lambda function. */
   // XXX: As it stands, this rule is a special case of what `MethodReferenceUsage` tries to achieve.
   // If/when `MethodReferenceUsage` becomes production ready, we should simply drop this check.

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/FileRules.java

@@ -2,15 +2,12 @@ package tech.picnic.errorprone.refasterrules;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 
-import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
-import java.io.File;
 import java.io.IOException;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.attribute.FileAttribute;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /** Refaster rules related to expressions dealing with files. */
@@ -43,24 +40,4 @@ final class FileRules {
       return Files.readString(path);
     }
   }
-
-  /**
-   * Prefer {@link Files#createTempFile(String, String, FileAttribute[])} over alternatives that
-   * create files with more liberal permissions.
-   */
-  static final class FilesCreateTempFileToFile {
-    @BeforeTemplate
-    @SuppressWarnings("java:S5443" /* This violation will be rewritten. */)
-    File before(String prefix, String suffix) throws IOException {
-      return Refaster.anyOf(
-          File.createTempFile(prefix, suffix), File.createTempFile(prefix, suffix, null));
-    }
-
-    @AfterTemplate
-    @SuppressWarnings(
-        "java:S5443" /* On POSIX systems the file will only have user read-write permissions. */)
-    File after(String prefix, String suffix) throws IOException {
-      return Files.createTempFile(prefix, suffix).toFile();
-    }
-  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/JUnitToAssertJRules.java

@@ -302,22 +302,16 @@ import tech.picnic.errorprone.refaster.annotation.TypeMigration;
 final class JUnitToAssertJRules {
   private JUnitToAssertJRules() {}
 
-  static final class Fail<T> {
+  static final class ThrowNewAssertionError {
     @BeforeTemplate
-    T before() {
-      return Assertions.fail();
+    void before() {
+      Assertions.fail();
     }
 
-    // XXX: Add `@UseImportPolicy(STATIC_IMPORT_ALWAYS)` once
-    // https://github.com/google/error-prone/pull/3584 is resolved. Until that time, statically
-    // importing AssertJ's `fail` is likely to clash with an existing static import of JUnit's
-    // `fail`. Note that combining Error Prone's `RemoveUnusedImports` and
-    // `UnnecessarilyFullyQualified` checks and our `StaticImport` check will anyway cause the
-    // method to be imported statically if possible; just in a less efficient manner.
     @AfterTemplate
     @DoNotCall
-    T after() {
-      return fail();
+    void after() {
+      throw new AssertionError();
     }
   }
 
@@ -327,7 +321,12 @@ final class JUnitToAssertJRules {
       return Assertions.fail(message);
     }
 
-    // XXX: Add `@UseImportPolicy(STATIC_IMPORT_ALWAYS)`. See `Fail` comment.
+    // XXX: Add `@UseImportPolicy(STATIC_IMPORT_ALWAYS)` once
+    // https://github.com/google/error-prone/pull/3584 is resolved. Until that time, statically
+    // importing AssertJ's `fail` is likely to clash with an existing static import of JUnit's
+    // `fail`. Note that combining Error Prone's `RemoveUnusedImports` and
+    // `UnnecessarilyFullyQualified` checks and our `StaticImport` check will anyway cause the
+    // method to be imported statically if possible; just in a less efficient manner.
     @AfterTemplate
     T after(String message) {
       return fail(message);
@@ -340,24 +339,28 @@ final class JUnitToAssertJRules {
       return Assertions.fail(message, throwable);
     }
 
-    // XXX: Add `@UseImportPolicy(STATIC_IMPORT_ALWAYS)`. See `Fail` comment.
+    // XXX: Add `@UseImportPolicy(STATIC_IMPORT_ALWAYS)` once
+    // https://github.com/google/error-prone/pull/3584 is resolved. Until that time, statically
+    // importing AssertJ's `fail` is likely to clash with an existing static import of JUnit's
+    // `fail`. Note that combining Error Prone's `RemoveUnusedImports` and
+    // `UnnecessarilyFullyQualified` checks and our `StaticImport` check will anyway cause the
+    // method to be imported statically if possible; just in a less efficient manner.
     @AfterTemplate
     T after(String message, Throwable throwable) {
       return fail(message, throwable);
     }
   }
 
-  static final class FailWithThrowable<T> {
+  static final class FailWithThrowable {
     @BeforeTemplate
-    T before(Throwable throwable) {
-      return Assertions.fail(throwable);
+    void before(Throwable throwable) {
+      Assertions.fail(throwable);
     }
 
-    // XXX: Add `@UseImportPolicy(STATIC_IMPORT_ALWAYS)`. See `Fail` comment.
     @AfterTemplate
     @DoNotCall
-    T after(Throwable throwable) {
-      return fail(throwable);
+    void after(Throwable throwable) {
+      throw new AssertionError(throwable);
     }
   }
 

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/OptionalRules.java

@@ -27,19 +27,6 @@ import tech.picnic.errorprone.refaster.matchers.IsLikelyTrivialComputation;
 final class OptionalRules {
   private OptionalRules() {}
 
-  /** Prefer {@link Optional#empty()} over the more contrived alternative. */
-  static final class OptionalEmpty<T> {
-    @BeforeTemplate
-    Optional<T> before() {
-      return Optional.ofNullable(null);
-    }
-
-    @AfterTemplate
-    Optional<T> after() {
-      return Optional.empty();
-    }
-  }
-
   static final class OptionalOfNullable<T> {
     // XXX: Refaster should be smart enough to also rewrite occurrences in which there are
     // parentheses around the null check, but that's currently not the case. Try to fix that.

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java

@@ -3,6 +3,7 @@ package tech.picnic.errorprone.refasterrules;
 import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.common.collect.ImmutableSet.toImmutableSet;
 import static com.google.common.collect.MoreCollectors.toOptional;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
 import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static java.util.Comparator.naturalOrder;
 import static java.util.Comparator.reverseOrder;
@@ -33,7 +34,6 @@ import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.Callable;
-import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
@@ -41,7 +41,6 @@ import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 import java.util.stream.Collector;
-import java.util.stream.Stream;
 import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
@@ -53,6 +52,7 @@ import reactor.util.context.Context;
 import reactor.util.function.Tuple2;
 import tech.picnic.errorprone.refaster.annotation.Description;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+import tech.picnic.errorprone.refaster.annotation.Severity;
 import tech.picnic.errorprone.refaster.matchers.IsEmpty;
 import tech.picnic.errorprone.refaster.matchers.IsIdentityOperation;
 import tech.picnic.errorprone.refaster.matchers.ThrowsCheckedException;
@@ -380,23 +380,30 @@ final class ReactorRules {
   }
 
   /**
-   * Prefer {@link Flux#take(long)} over {@link Flux#take(long, boolean)} where relevant.
+   * Prefer {@link Flux#take(long, boolean)} over {@link Flux#take(long)}.
    *
    * <p>In Reactor versions prior to 3.5.0, {@code Flux#take(long)} makes an unbounded request
-   * upstream, and is equivalent to {@code Flux#take(long, false)}. From version 3.5.0 onwards, the
-   * behavior of {@code Flux#take(long)} instead matches {@code Flux#take(long, true)}.
+   * upstream, and is equivalent to {@code Flux#take(long, false)}. In 3.5.0, the behavior of {@code
+   * Flux#take(long)} will change to that of {@code Flux#take(long, true)}.
+   *
+   * <p>The intent with this Refaster rule is to get the new behavior before upgrading to Reactor
+   * 3.5.0.
    */
+  // XXX: Drop this rule some time after upgrading to Reactor 3.6.0, or introduce a way to apply
+  // this rule only when an older version of Reactor is on the classpath.
+  // XXX: Once Reactor 3.6.0 is out, introduce a rule that rewrites code in the opposite direction.
   @Description(
-      "From Reactor 3.5.0 onwards, `take(n)` no longer requests an unbounded number of elements upstream.")
+      "Prior to Reactor 3.5.0, `take(n)` requests and unbounded number of elements upstream.")
+  @Severity(WARNING)
   static final class FluxTake<T> {
     @BeforeTemplate
     Flux<T> before(Flux<T> flux, long n) {
-      return flux.take(n, /* limitRequest= */ true);
+      return flux.take(n);
     }
 
     @AfterTemplate
     Flux<T> after(Flux<T> flux, long n) {
-      return flux.take(n);
+      return flux.take(n, /* limitRequest= */ true);
     }
   }
 
@@ -482,20 +489,15 @@ final class ReactorRules {
   }
 
   /** Prefer {@link Flux#just(Object)} over more contrived alternatives. */
-  static final class FluxJust<T> {
+  static final class FluxJust {
     @BeforeTemplate
-    Flux<Integer> before(int value) {
-      return Flux.range(value, 1);
-    }
-
-    @BeforeTemplate
-    Flux<T> before(T value) {
-      return Mono.just(value).repeat().take(1);
+    Flux<Integer> before(int start) {
+      return Flux.range(start, 1);
     }
 
     @AfterTemplate
-    Flux<T> after(T value) {
-      return Flux.just(value);
+    Flux<Integer> after(int start) {
+      return Flux.just(start);
     }
   }
 
@@ -564,7 +566,6 @@ final class ReactorRules {
         @Matches(IsIdentityOperation.class)
             Function<? super P, ? extends Publisher<? extends S>> identityOperation) {
       return Refaster.anyOf(
-          flux.concatMap(function, 0),
           flux.flatMap(function, 1),
           flux.flatMapSequential(function, 1),
           flux.map(function).concatMap(identityOperation));
@@ -1205,17 +1206,10 @@ final class ReactorRules {
   }
 
   /** Prefer {@link Flux#fromIterable(Iterable)} over less efficient alternatives. */
-  // XXX: Once the `FluxFromStreamSupplier` rule is constrained using
-  // `@NotMatches(IsIdentityOperation.class)`, this rule should also cover
-  // `Flux.fromStream(collection.stream())`.
   static final class FluxFromIterable<T> {
-    // XXX: Once the `MethodReferenceUsage` check is generally enabled, drop the second
-    // `Refaster.anyOf` variant.
     @BeforeTemplate
     Flux<T> before(Collection<T> collection) {
-      return Flux.fromStream(
-          Refaster.<Supplier<Stream<? extends T>>>anyOf(
-              collection::stream, () -> collection.stream()));
+      return Flux.fromStream(collection.stream());
     }
 
     @AfterTemplate
@@ -1918,60 +1912,4 @@ final class ReactorRules {
       return step.verifyTimeout(duration);
     }
   }
-
-  /**
-   * Prefer {@link Mono#fromFuture(Supplier)} over {@link Mono#fromFuture(CompletableFuture)}, as
-   * the former may defer initiation of the asynchronous computation until subscription.
-   */
-  static final class MonoFromFutureSupplier<T> {
-    // XXX: Constrain the `future` parameter using `@NotMatches(IsIdentityOperation.class)` once
-    // `IsIdentityOperation` no longer matches nullary method invocations.
-    @BeforeTemplate
-    Mono<T> before(CompletableFuture<T> future) {
-      return Mono.fromFuture(future);
-    }
-
-    @AfterTemplate
-    Mono<T> after(CompletableFuture<T> future) {
-      return Mono.fromFuture(() -> future);
-    }
-  }
-
-  /**
-   * Prefer {@link Mono#fromFuture(Supplier, boolean)} over {@link
-   * Mono#fromFuture(CompletableFuture, boolean)}, as the former may defer initiation of the
-   * asynchronous computation until subscription.
-   */
-  static final class MonoFromFutureSupplierBoolean<T> {
-    // XXX: Constrain the `future` parameter using `@NotMatches(IsIdentityOperation.class)` once
-    // `IsIdentityOperation` no longer matches nullary method invocations.
-    @BeforeTemplate
-    Mono<T> before(CompletableFuture<T> future, boolean suppressCancel) {
-      return Mono.fromFuture(future, suppressCancel);
-    }
-
-    @AfterTemplate
-    Mono<T> after(CompletableFuture<T> future, boolean suppressCancel) {
-      return Mono.fromFuture(() -> future, suppressCancel);
-    }
-  }
-
-  /**
-   * Prefer {@link Flux#fromStream(Supplier)} over {@link Flux#fromStream(Stream)}, as the former
-   * yields a {@link Flux} that is more likely to behave as expected when subscribed to more than
-   * once.
-   */
-  static final class FluxFromStreamSupplier<T> {
-    // XXX: Constrain the `stream` parameter using `@NotMatches(IsIdentityOperation.class)` once
-    // `IsIdentityOperation` no longer matches nullary method invocations.
-    @BeforeTemplate
-    Flux<T> before(Stream<T> stream) {
-      return Flux.fromStream(stream);
-    }
-
-    @AfterTemplate
-    Flux<T> after(Stream<T> stream) {
-      return Flux.fromStream(() -> stream);
-    }
-  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/TestNGToAssertJRules.java

@@ -161,9 +161,8 @@ final class TestNGToAssertJRules {
 
     @AfterTemplate
     @DoNotCall
-    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after() {
-      fail();
+      throw new AssertionError();
     }
   }
 

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ClassRulesTestInput.java

@@ -1,34 +1,26 @@
 package tech.picnic.errorprone.refasterrules;
 
 import com.google.common.collect.ImmutableSet;
-import java.util.function.Function;
+import java.io.IOException;
 import java.util.function.Predicate;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class ClassRulesTest implements RefasterRuleCollectionTestCase {
-  boolean testClassIsInstance() {
+  boolean testClassIsInstance() throws IOException {
     return CharSequence.class.isAssignableFrom("foo".getClass());
   }
 
-  ImmutableSet<Boolean> testInstanceof() {
+  ImmutableSet<Boolean> testInstanceof() throws IOException {
     Class<?> clazz = CharSequence.class;
     return ImmutableSet.of(CharSequence.class.isInstance("foo"), clazz.isInstance("bar"));
   }
 
-  Predicate<String> testClassLiteralIsInstancePredicate() {
+  Predicate<String> testClassLiteralIsInstancePredicate() throws IOException {
     return s -> s instanceof CharSequence;
   }
 
-  Predicate<String> testClassReferenceIsInstancePredicate() {
+  Predicate<String> testClassReferenceIsInstancePredicate() throws IOException {
     Class<?> clazz = CharSequence.class;
     return s -> clazz.isInstance(s);
   }
-
-  Function<Number, Integer> testClassLiteralCast() {
-    return i -> (Integer) i;
-  }
-
-  Function<Number, Integer> testClassReferenceCast() {
-    return i -> Integer.class.cast(i);
-  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ClassRulesTestOutput.java

@@ -1,34 +1,26 @@
 package tech.picnic.errorprone.refasterrules;
 
 import com.google.common.collect.ImmutableSet;
-import java.util.function.Function;
+import java.io.IOException;
 import java.util.function.Predicate;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class ClassRulesTest implements RefasterRuleCollectionTestCase {
-  boolean testClassIsInstance() {
+  boolean testClassIsInstance() throws IOException {
     return CharSequence.class.isInstance("foo");
   }
 
-  ImmutableSet<Boolean> testInstanceof() {
+  ImmutableSet<Boolean> testInstanceof() throws IOException {
     Class<?> clazz = CharSequence.class;
     return ImmutableSet.of("foo" instanceof CharSequence, clazz.isInstance("bar"));
   }
 
-  Predicate<String> testClassLiteralIsInstancePredicate() {
+  Predicate<String> testClassLiteralIsInstancePredicate() throws IOException {
     return CharSequence.class::isInstance;
   }
 
-  Predicate<String> testClassReferenceIsInstancePredicate() {
+  Predicate<String> testClassReferenceIsInstancePredicate() throws IOException {
     Class<?> clazz = CharSequence.class;
     return clazz::isInstance;
   }
-
-  Function<Number, Integer> testClassLiteralCast() {
-    return Integer.class::cast;
-  }
-
-  Function<Number, Integer> testClassReferenceCast() {
-    return Integer.class::cast;
-  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/CollectionRulesTestInput.java

@@ -6,11 +6,9 @@ import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedList;
-import java.util.List;
 import java.util.Optional;
 import java.util.TreeSet;
 import java.util.stream.Stream;
@@ -72,10 +70,6 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
     }
   }
 
-  Stream<Integer> testSetStream() {
-    return ImmutableSet.of(1).stream().distinct();
-  }
-
   ArrayList<String> testNewArrayListFromCollection() {
     return Lists.newArrayList(ImmutableList.of("foo"));
   }
@@ -100,10 +94,6 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableSet.of(1).asList().toString();
   }
 
-  List<String> testArraysAsList() {
-    return Arrays.stream(new String[0]).toList();
-  }
-
   ImmutableSet<Object[]> testCollectionToArray() {
     return ImmutableSet.of(
         ImmutableSet.of(1).toArray(new Object[1]),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/CollectionRulesTestOutput.java

@@ -6,11 +6,9 @@ import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedList;
-import java.util.List;
 import java.util.Optional;
 import java.util.TreeSet;
 import java.util.stream.Stream;
@@ -64,10 +62,6 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
     new HashSet<Number>().removeAll(ImmutableSet.of(2));
   }
 
-  Stream<Integer> testSetStream() {
-    return ImmutableSet.of(1).stream();
-  }
-
   ArrayList<String> testNewArrayListFromCollection() {
     return new ArrayList<>(ImmutableList.of("foo"));
   }
@@ -92,10 +86,6 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableSet.of(1).toString();
   }
 
-  List<String> testArraysAsList() {
-    return Arrays.asList(new String[0]);
-  }
-
   ImmutableSet<Object[]> testCollectionToArray() {
     return ImmutableSet.of(
         ImmutableSet.of(1).toArray(), ImmutableSet.of(2).toArray(), ImmutableSet.of(3).toArray());

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/EqualityRulesTestInput.java

@@ -1,6 +1,5 @@
 package tech.picnic.errorprone.refasterrules;
 
-import static java.util.function.Predicate.isEqual;
 import static java.util.function.Predicate.not;
 
 import com.google.common.collect.BoundType;
@@ -15,10 +14,10 @@ import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 final class EqualityRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<Object> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(Objects.class, Optional.class, isEqual(null), not(null));
+    return ImmutableSet.of(Objects.class, Optional.class, not(null));
   }
 
-  ImmutableSet<Boolean> testEnumReferenceEquality() {
+  ImmutableSet<Boolean> testPrimitiveOrReferenceEquality() {
     return ImmutableSet.of(
         RoundingMode.UP.equals(RoundingMode.DOWN),
         Objects.equals(RoundingMode.UP, RoundingMode.DOWN),
@@ -28,10 +27,6 @@ final class EqualityRulesTest implements RefasterRuleCollectionTestCase {
         RoundingMode.UP.ordinal() != RoundingMode.DOWN.ordinal());
   }
 
-  ImmutableSet<Predicate<RoundingMode>> testEnumReferenceEqualityLambda() {
-    return ImmutableSet.of(isEqual(RoundingMode.DOWN), RoundingMode.UP::equals);
-  }
-
   boolean testEqualsPredicate() {
     // XXX: When boxing is involved this rule seems to break. Example:
     // Stream.of(1).anyMatch(e -> Integer.MIN_VALUE.equals(e));

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/EqualityRulesTestOutput.java

@@ -1,6 +1,5 @@
 package tech.picnic.errorprone.refasterrules;
 
-import static java.util.function.Predicate.isEqual;
 import static java.util.function.Predicate.not;
 
 import com.google.common.collect.BoundType;
@@ -15,10 +14,10 @@ import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 final class EqualityRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<Object> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(Objects.class, Optional.class, isEqual(null), not(null));
+    return ImmutableSet.of(Objects.class, Optional.class, not(null));
   }
 
-  ImmutableSet<Boolean> testEnumReferenceEquality() {
+  ImmutableSet<Boolean> testPrimitiveOrReferenceEquality() {
     return ImmutableSet.of(
         RoundingMode.UP == RoundingMode.DOWN,
         RoundingMode.UP == RoundingMode.DOWN,
@@ -28,10 +27,6 @@ final class EqualityRulesTest implements RefasterRuleCollectionTestCase {
         RoundingMode.UP != RoundingMode.DOWN);
   }
 
-  ImmutableSet<Predicate<RoundingMode>> testEnumReferenceEqualityLambda() {
-    return ImmutableSet.of(v -> v == RoundingMode.DOWN, v -> v == RoundingMode.UP);
-  }
-
   boolean testEqualsPredicate() {
     // XXX: When boxing is involved this rule seems to break. Example:
     // Stream.of(1).anyMatch(e -> Integer.MIN_VALUE.equals(e));

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/FileRulesTestInput.java

@@ -1,7 +1,5 @@
 package tech.picnic.errorprone.refasterrules;
 
-import com.google.common.collect.ImmutableSet;
-import java.io.File;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
@@ -16,9 +14,4 @@ final class FileRulesTest implements RefasterRuleCollectionTestCase {
   String testFilesReadString() throws IOException {
     return Files.readString(Paths.get("foo"), StandardCharsets.UTF_8);
   }
-
-  ImmutableSet<File> testFilesCreateTempFileToFile() throws IOException {
-    return ImmutableSet.of(
-        File.createTempFile("foo", "bar"), File.createTempFile("baz", "qux", null));
-  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/FileRulesTestOutput.java

@@ -1,7 +1,5 @@
 package tech.picnic.errorprone.refasterrules;
 
-import com.google.common.collect.ImmutableSet;
-import java.io.File;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
@@ -16,9 +14,4 @@ final class FileRulesTest implements RefasterRuleCollectionTestCase {
   String testFilesReadString() throws IOException {
     return Files.readString(Paths.get("foo"));
   }
-
-  ImmutableSet<File> testFilesCreateTempFileToFile() throws IOException {
-    return ImmutableSet.of(
-        Files.createTempFile("foo", "bar").toFile(), Files.createTempFile("baz", "qux").toFile());
-  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/JUnitToAssertJRulesTestInput.java

@@ -32,8 +32,8 @@ final class JUnitToAssertJRulesTest implements RefasterRuleCollectionTestCase {
         (Runnable) () -> assertTrue(true));
   }
 
-  Object testFail() {
-    return Assertions.fail();
+  void testThrowNewAssertionError() {
+    Assertions.fail();
   }
 
   Object testFailWithMessage() {
@@ -44,8 +44,8 @@ final class JUnitToAssertJRulesTest implements RefasterRuleCollectionTestCase {
     return Assertions.fail("foo", new IllegalStateException());
   }
 
-  Object testFailWithThrowable() {
-    return Assertions.fail(new IllegalStateException());
+  void testFailWithThrowable() {
+    Assertions.fail(new IllegalStateException());
   }
 
   void testAssertThatIsTrue() {

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/JUnitToAssertJRulesTestOutput.java

@@ -35,8 +35,8 @@ final class JUnitToAssertJRulesTest implements RefasterRuleCollectionTestCase {
         (Runnable) () -> assertTrue(true));
   }
 
-  Object testFail() {
-    return org.assertj.core.api.Assertions.fail();
+  void testThrowNewAssertionError() {
+    throw new AssertionError();
   }
 
   Object testFailWithMessage() {
@@ -47,8 +47,8 @@ final class JUnitToAssertJRulesTest implements RefasterRuleCollectionTestCase {
     return org.assertj.core.api.Assertions.fail("foo", new IllegalStateException());
   }
 
-  Object testFailWithThrowable() {
-    return org.assertj.core.api.Assertions.fail(new IllegalStateException());
+  void testFailWithThrowable() {
+    throw new AssertionError(new IllegalStateException());
   }
 
   void testAssertThatIsTrue() {

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/OptionalRulesTestInput.java

@@ -13,10 +13,6 @@ final class OptionalRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableSet.of(Streams.class);
   }
 
-  Optional<String> testOptionalEmpty() {
-    return Optional.ofNullable(null);
-  }
-
   ImmutableSet<Optional<String>> testOptionalOfNullable() {
     return ImmutableSet.of(
         toString() == null ? Optional.empty() : Optional.of(toString()),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/OptionalRulesTestOutput.java

@@ -15,10 +15,6 @@ final class OptionalRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableSet.of(Streams.class);
   }
 
-  Optional<String> testOptionalEmpty() {
-    return Optional.empty();
-  }
-
   ImmutableSet<Optional<String>> testOptionalOfNullable() {
     return ImmutableSet.of(Optional.ofNullable(toString()), Optional.ofNullable(toString()));
   }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java

@@ -21,9 +21,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.Callable;
-import java.util.concurrent.CompletableFuture;
 import java.util.function.Supplier;
-import java.util.stream.Stream;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.math.MathFlux;
@@ -144,7 +142,7 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
   }
 
   Flux<Integer> testFluxTake() {
-    return Flux.just(1, 2, 3).take(1, true);
+    return Flux.just(1, 2, 3).take(1);
   }
 
   Mono<String> testMonoDefaultIfEmpty() {
@@ -184,8 +182,8 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
         Flux.range(0, 0));
   }
 
-  ImmutableSet<Flux<Integer>> testFluxJust() {
-    return ImmutableSet.of(Flux.range(0, 1), Mono.just(2).repeat().take(1));
+  Flux<Integer> testFluxJust() {
+    return Flux.range(0, 1);
   }
 
   ImmutableSet<Mono<?>> testMonoIdentity() {
@@ -209,12 +207,11 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
 
   ImmutableSet<Flux<Integer>> testFluxConcatMap() {
     return ImmutableSet.of(
-        Flux.just(1).concatMap(Mono::just, 0),
-        Flux.just(2).flatMap(Mono::just, 1),
-        Flux.just(3).flatMapSequential(Mono::just, 1),
-        Flux.just(4).map(Mono::just).concatMap(identity()),
-        Flux.just(5).map(Mono::just).concatMap(v -> v),
-        Flux.just(6).map(Mono::just).concatMap(v -> Mono.empty()));
+        Flux.just(1).flatMap(Mono::just, 1),
+        Flux.just(2).flatMapSequential(Mono::just, 1),
+        Flux.just(3).map(Mono::just).concatMap(identity()),
+        Flux.just(4).map(Mono::just).concatMap(v -> v),
+        Flux.just(5).map(Mono::just).concatMap(v -> Mono.empty()));
   }
 
   ImmutableSet<Flux<Integer>> testFluxConcatMapWithPrefetch() {
@@ -435,10 +432,8 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
         Flux.just(ImmutableList.of("bar")).concatMap(Flux::fromIterable, 2));
   }
 
-  ImmutableSet<Flux<String>> testFluxFromIterable() {
-    return ImmutableSet.of(
-        Flux.fromStream(ImmutableList.of("foo")::stream),
-        Flux.fromStream(() -> ImmutableList.of("bar").stream()));
+  Flux<String> testFluxFromIterable() {
+    return Flux.fromStream(ImmutableList.of("foo").stream());
   }
 
   ImmutableSet<Mono<Integer>> testFluxCountMapMathToIntExact() {
@@ -655,16 +650,4 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
   Duration testStepVerifierLastStepVerifyTimeout() {
     return Mono.empty().as(StepVerifier::create).expectTimeout(Duration.ZERO).verify();
   }
-
-  Mono<Void> testMonoFromFutureSupplier() {
-    return Mono.fromFuture(CompletableFuture.completedFuture(null));
-  }
-
-  Mono<Void> testMonoFromFutureSupplierBoolean() {
-    return Mono.fromFuture(CompletableFuture.completedFuture(null), true);
-  }
-
-  Flux<Integer> testFluxFromStreamSupplier() {
-    return Flux.fromStream(Stream.of(1));
-  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java

@@ -23,9 +23,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.Callable;
-import java.util.concurrent.CompletableFuture;
 import java.util.function.Supplier;
-import java.util.stream.Stream;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.function.TupleUtils;
@@ -149,7 +147,7 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
   }
 
   Flux<Integer> testFluxTake() {
-    return Flux.just(1, 2, 3).take(1);
+    return Flux.just(1, 2, 3).take(1, true);
   }
 
   Mono<String> testMonoDefaultIfEmpty() {
@@ -188,8 +186,8 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
         Flux.empty());
   }
 
-  ImmutableSet<Flux<Integer>> testFluxJust() {
-    return ImmutableSet.of(Flux.just(0), Flux.just(2));
+  Flux<Integer> testFluxJust() {
+    return Flux.just(0);
   }
 
   ImmutableSet<Mono<?>> testMonoIdentity() {
@@ -216,8 +214,7 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
         Flux.just(2).concatMap(Mono::just),
         Flux.just(3).concatMap(Mono::just),
         Flux.just(4).concatMap(Mono::just),
-        Flux.just(5).concatMap(Mono::just),
-        Flux.just(6).map(Mono::just).concatMap(v -> Mono.empty()));
+        Flux.just(5).map(Mono::just).concatMap(v -> Mono.empty()));
   }
 
   ImmutableSet<Flux<Integer>> testFluxConcatMapWithPrefetch() {
@@ -430,9 +427,8 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
         Flux.just(ImmutableList.of("bar")).concatMapIterable(identity(), 2));
   }
 
-  ImmutableSet<Flux<String>> testFluxFromIterable() {
-    return ImmutableSet.of(
-        Flux.fromIterable(ImmutableList.of("foo")), Flux.fromIterable(ImmutableList.of("bar")));
+  Flux<String> testFluxFromIterable() {
+    return Flux.fromIterable(ImmutableList.of("foo"));
   }
 
   ImmutableSet<Mono<Integer>> testFluxCountMapMathToIntExact() {
@@ -635,16 +631,4 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
   Duration testStepVerifierLastStepVerifyTimeout() {
     return Mono.empty().as(StepVerifier::create).verifyTimeout(Duration.ZERO);
   }
-
-  Mono<Void> testMonoFromFutureSupplier() {
-    return Mono.fromFuture(() -> CompletableFuture.completedFuture(null));
-  }
-
-  Mono<Void> testMonoFromFutureSupplierBoolean() {
-    return Mono.fromFuture(() -> CompletableFuture.completedFuture(null), true);
-  }
-
-  Flux<Integer> testFluxFromStreamSupplier() {
-    return Flux.fromStream(() -> Stream.of(1));
-  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/TestNGToAssertJRulesTestOutput.java

@@ -41,7 +41,7 @@ final class TestNGToAssertJRulesTest implements RefasterRuleCollectionTestCase {
   }
 
   void testFail() {
-    fail();
+    throw new AssertionError();
   }
 
   void testFailWithMessage() {

error-prone-experimental/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.18.0</version>
+        <version>0.16.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-experimental</artifactId>

error-prone-guidelines/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.18.0</version>
+        <version>0.16.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-guidelines</artifactId>

error-prone-utils/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.18.0</version>
+        <version>0.16.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-utils</artifactId>

integration-tests/checkstyle.sh

@@ -2,35 +2,211 @@
 
 set -e -u -o pipefail
 
+integration_test_root="$(cd "$(dirname -- "${0}")" && pwd)"
+error_prone_support_root="${integration_test_root}/.."
+repos_root="${integration_test_root}/.repos"
+
 test_name="$(basename "${0}" .sh)"
-project='checkstyle'
-repository='https://github.com/checkstyle/checkstyle.git'
-revision='checkstyle-10.14.0'
-# XXX: Configure Renovate to manage the AssertJ version declared here.
-additional_build_flags='-Dassertj.version=3.24.2'
-additional_source_directories='${project.basedir}${file.separator}src${file.separator}it${file.separator}java,${project.basedir}${file.separator}src${file.separator}xdocs-examples${file.separator}java'
-patch_error_prone_flags=''
-validation_error_prone_flags=''
-# Validation skips some tests:
-# - The `metadataFilesGenerationAllFiles` test is skipped because it makes line
-#   number assertions that will fail when the code is formatted or patched.
-# - The `allCheckSectionJavaDocs` test is skipped because it validates that
-#   Javadoc has certain closing tags that are removed by Google Java Format.
-validation_build_flags='-Dtest=!MetadataGeneratorUtilTest#metadataFilesGenerationAllFiles,!XdocsJavaDocsTest#allCheckSectionJavaDocs'
+project=checkstyle
+repository=https://github.com/checkstyle/checkstyle.git
+revision=checkstyle-10.14.0
 
 if [ "${#}" -gt 2 ] || ([ "${#}" = 2 ] && [ "${1:---sync}" != '--sync' ]); then
-  >&2 echo "Usage: ${0} [--sync] [<report_directory>]"
+  echo "Usage: ${0} [--sync] [<report_directory>]"
   exit 1
 fi
+do_sync="$([ "${#}" = 0 ] || [ "${1:-}" != '--sync' ] || echo 1)"
+report_directory="$([ "${#}" = 0 ] || ([ -z "${do_sync}" ] && echo "${1}") || ([ "${#}" = 1 ] || echo "${2}"))"
 
-"$(dirname "${0}")/run-integration-test.sh" \
-  "${test_name}" \
-  "${project}" \
-  "${repository}" \
-  "${revision}" \
-  "${additional_build_flags}" \
-  "${additional_source_directories}" \
-  "${patch_error_prone_flags}" \
-  "${validation_error_prone_flags}" \
-  "${validation_build_flags}" \
-  $@
+if [ -n "${report_directory}" ]; then
+  mkdir -p "${report_directory}"
+else
+  report_directory="$(mktemp -d)"
+  trap 'rm -rf -- "${report_directory}"' INT TERM HUP EXIT
+fi
+
+case "$(uname -s)" in
+  Linux*)
+    grep_command=grep
+    sed_command=sed
+    ;;
+  Darwin*)
+    grep_command=ggrep
+    sed_command=gsed
+    ;;
+  *)
+    echo "Unsupported distribution $(uname -s) for this script."
+    exit 1
+    ;;
+esac
+
+# XXX: Configure Renovate to manage the AssertJ version declared here.
+shared_build_flags="
+  -Perror-prone-compile,error-prone-test-compile
+  -Dassertj.version=3.24.2
+  -Derror-prone.version=$(
+    mvn -f "${error_prone_support_root}" help:evaluate -Dexpression=version.error-prone -q -DforceStdout
+  )
+  -Derror-prone-support.version=$(
+    mvn -f "${error_prone_support_root}" help:evaluate -Dexpression=project.version -q -DforceStdout
+  )
+  -DadditionalSourceDirectories=\${project.basedir}\${file.separator}src\${file.separator}it\${file.separator}java,\${project.basedir}\${file.separator}src\${file.separator}xdocs-examples\${file.separator}java
+  "
+
+# XXX: Configure Renovate to manage the fmt-maven-plugin version declared here.
+# XXX: Once GitHub actions uses Maven 3.9.2+, we can inline this variable with
+# version reference `${fmt.version}`, and `-Dfmt.version=2.21.1` added to
+# `shared_build_flags`.
+format_goal='com.spotify.fmt:fmt-maven-plugin:2.21.1:format'
+
+error_prone_shared_flags='-XepExcludedPaths:(\Q${project.basedir}${file.separator}src${file.separator}\E(it|test|xdocs-examples)\Q${file.separator}resources\E|\Q${project.build.directory}${file.separator}\E).*'
+
+error_prone_patch_flags="${error_prone_shared_flags} -XepPatchLocation:IN_PLACE -XepPatchChecks:$(
+  find "${error_prone_support_root}" \
+     -path "*/META-INF/services/com.google.errorprone.bugpatterns.BugChecker" \
+     -not -path "*/error-prone-experimental/*" \
+     -not -path "*/error-prone-guidelines/*" \
+     -not -path "*/error-prone-contrib/*" \
+     -print0 \
+    | xargs -0 "${grep_command}" -hoP '[^.]+$' \
+    | paste -s -d ',' -
+) -XepOpt:Refaster:NamePattern=.*Workshop.*"
+
+error_prone_validation_flags="${error_prone_shared_flags} -XepDisableAllChecks $(
+  find "${error_prone_support_root}" \
+     -path "*/META-INF/services/com.google.errorprone.bugpatterns.BugChecker" \
+     -not -path "*/error-prone-experimental/*" \
+     -not -path "*/error-prone-guidelines/*" \
+     -not -path "*/error-prone-contrib/*" \
+     -print0 \
+    | xargs -0 "${grep_command}" -hoP "[^.]+$' \
+    | "${sed_command}" -r 's,(.*),-Xep:\1:WARN,' \
+    | paste -s -d ' ' -
+) -XepOpt:Refaster:NamePattern=.*Workshop.*"
+
+echo "Shared build flags: ${shared_build_flags}"
+echo "Error Prone patch flags: ${error_prone_patch_flags}"
+echo "Error Prone validation flags: ${error_prone_validation_flags}"
+
+mkdir -p "${repos_root}"
+
+# Make sure that the targeted tag of the project's Git repository is checked
+# out.
+project_root="${repos_root}/${project}"
+if [ ! -d "${project_root}" ]; then
+  # The repository has not yet been cloned; create a shallow clone.
+  git clone --branch "${revision}" --depth 1 "${repository}" "${project_root}"
+else
+  # The repository does already appear to exist. Try to check out the requested
+  # tag if possible, and fetch it otherwise.
+  #
+  # Under certain circumstances this does not cause the relevant tag to be
+  # created, so if necessary we manually create it.
+  git -C "${project_root}" checkout --force "${revision}" 2>/dev/null \
+    || (
+         git -C "${project_root}" fetch --depth 1 "${repository}" "${revision}" \
+           && git -C "${project_root}" checkout --force FETCH_HEAD \
+           && (git -C "${project_root}" tag "${revision}" || true)
+       )
+fi
+
+pushd "${project_root}"
+
+# Make sure that Git is sufficiently configured to enable committing to the
+# project's Git repository.
+git config user.email || git config user.email "integration-test@example.com"
+git config user.name || git config user.name "Integration Test"
+
+# Prepare the code for analysis by (a) applying the minimal set of changes
+# required to run Error Prone with Error Prone Support and (b) formatting the
+# code using the same method by which it will be formatted after each
+# compilation round. The initial formatting operation ensures that subsequent
+# modifications can be rendered in a clean manner.
+git clean -fdx
+git apply < "${integration_test_root}/${test_name}-init.patch"
+git commit -m 'dependency: Introduce Error Prone Support' .
+mvn ${shared_build_flags} "${format_goal}"
+git commit -m 'minor: Reformat using Google Java Format' .
+diff_base="$(git rev-parse HEAD)"
+
+# Apply Error Prone Support-suggested changes until a fixed point is reached.
+function apply_patch() {
+  local extra_build_args="${1}"
+
+  mvn ${shared_build_flags} ${extra_build_args} \
+    package "${format_goal}" \
+    -Derror-prone.configuration-args="${error_prone_patch_flags}" \
+    -DskipTests
+
+  if ! git diff --exit-code; then
+    git commit -m 'minor: Apply patches' .
+
+    # Changes were applied, so another compilation round may apply yet more
+    # changes. For performance reasons we perform incremental compilation,
+    # enabled using a misleading flag. (See
+    # https://issues.apache.org/jira/browse/MCOMPILER-209 for details.)
+    apply_patch '-Dmaven.compiler.useIncrementalCompilation=false'
+  elif [ "${extra_build_args}" != 'clean' ]; then
+    # No changes were applied. We'll attempt one more round in which all files
+    # are recompiled, because there are cases in which violations are missed
+    # during incremental compilation.
+    apply_patch 'clean'
+  fi
+}
+apply_patch ''
+
+# Run one more full build and log the output.
+#
+# By also running the tests, we validate that the (majority of) applied changes
+# are behavior preserving. Some tests are skipped:
+# - The `metadataFilesGenerationAllFiles` test is skipped because it makes line
+#   number assertions that will fail when the code is formatted or patched.
+# - The `allCheckSectionJavaDocs` test is skipped because is validates that
+#   Javadoc has certain closing tags that are removed by Google Java Format.
+validation_build_log="${report_directory}/${test_name}-validation-build-log.txt"
+mvn ${shared_build_flags} \
+      clean package \
+      -Derror-prone.configuration-args="${error_prone_validation_flags}" \
+      -Dtest='
+        !MetadataGeneratorUtilTest#metadataFilesGenerationAllFiles,
+        !XdocsJavaDocsTest#allCheckSectionJavaDocs' \
+      -Dstyle.color=always \
+    | tee "${validation_build_log}" \
+  || failure=1
+
+# Collect the applied changes.
+expected_changes="${integration_test_root}/${test_name}-expected-changes.patch"
+actual_changes="${report_directory}/${test_name}-changes.patch"
+(git diff "${diff_base}"..HEAD | "${grep_command}" -vP '^(diff|index)' || true) > "${actual_changes}"
+
+# Collect the warnings reported by Error Prone Support checks.
+expected_warnings="${integration_test_root}/${test_name}-expected-warnings.txt"
+actual_warnings="${report_directory}/${test_name}-validation-build-warnings.txt"
+("${grep_command}" -oP "(?<=^\\Q[WARNING] ${PWD}/\\E).*" "${validation_build_log}" | "${grep_command}" -P '\] \[' || true) | LC_ALL=C sort > "${actual_warnings}"
+
+# Persist or validate the applied changes and reported warnings.
+if [ -n "${do_sync}" ]; then
+  echo 'Saving changes...'
+  cp "${actual_changes}" "${expected_changes}"
+  cp "${actual_warnings}" "${expected_warnings}"
+else
+  echo 'Inspecting changes...'
+  # XXX: This "diff of diffs" also contains vacuous sections, introduced due to
+  # line offset differences. Try to omit those from the final output.
+  if ! diff -u "${expected_changes}" "${actual_changes}"; then
+    echo 'There are unexpected changes.'
+    echo "Inspect the changes here: ${report_directory}/${test_name}-diff-of-diffs-changes.patch"
+    diff -u "${expected_changes}" "${actual_changes}" > "${report_directory}/${test_name}-diff-of-diffs-changes.patch"
+    failure=1
+  fi
+  echo 'Inspecting emitted warnings...'
+  if ! diff -u "${expected_warnings}" "${actual_warnings}"; then
+    echo 'Diagnostics output changed.'
+    diff -u "${expected_warnings}" "${actual_warnings}" > "${report_directory}/${test_name}-diff-of-diffs-warnings.patch"
+    failure=1
+  fi
+fi
+
+if [ -n "${failure:-}" ]; then
+  exit 1
+fi

integration-tests/run-integration-test.sh

@@ -1,210 +0,0 @@
-#!/usr/bin/env bash
-
-# Integration test framework for Maven builds.
-#
-# This script is not meant to be invoked manually. Instead it should be invoked
-# through one of the top-level integration test scripts, such as
-# `checkstyle.sh`.
-
-set -e -u -o pipefail
-
-integration_test_root="$(cd "$(dirname -- "${0}")" && pwd)"
-error_prone_support_root="${integration_test_root}/.."
-repos_root="${integration_test_root}/.repos"
-
-if [ "${#}" -lt 9 ] || [ "${#}" -gt 11 ] || ([ "${#}" = 11 ] && [ "${10:---sync}" != '--sync' ]); then
-  >&2 echo "Usage: $(basename "${0}") <test_name> <project> <repository> <revision> <additional_build_flags> <additional_source_directories> <patch_error_prone_flags> <validation_error_prone_flags> <validation_build_flags> [--sync] [<report_directory>]"
-  exit 1
-fi
-
-test_name="${1}"
-project="${2}"
-repository="${3}"
-revision="${4}"
-additional_build_flags="${5}"
-additional_source_directories="${6}"
-patch_error_prone_flags="${7}"
-validation_error_prone_flags="${8}"
-validation_build_flags="${9}"
-do_sync="$([ "${#}" = 9 ] || [ "${10:-}" != '--sync' ] || echo 1)"
-report_directory="$([ "${#}" = 9 ] || ([ -z "${do_sync}" ] && echo "${10}") || ([ "${#}" = 10 ] || echo "${11}"))"
-
-if [ -n "${report_directory}" ]; then
-  mkdir -p "${report_directory}"
-else
-  report_directory="$(mktemp -d)"
-  trap 'rm -rf -- "${report_directory}"' INT TERM HUP EXIT
-fi
-
-case "$(uname -s)" in
-  Linux*)
-    grep_command=grep
-    sed_command=sed
-    ;;
-  Darwin*)
-    grep_command=ggrep
-    sed_command=gsed
-    ;;
-  *)
-    echo "Unsupported distribution $(uname -s) for this script."
-    exit 1
-    ;;
-esac
-
-shared_build_flags="
-  -Perror-prone-compile,error-prone-test-compile
-  -Derror-prone.version=$(
-    mvn -f "${error_prone_support_root}" help:evaluate -Dexpression=version.error-prone -q -DforceStdout
-  )
-  -Derror-prone-support.version=$(
-    mvn -f "${error_prone_support_root}" help:evaluate -Dexpression=project.version -q -DforceStdout
-  )
-  -DadditionalSourceDirectories=${additional_source_directories}
-  ${additional_build_flags}
-  "
-
-# XXX: Configure Renovate to manage the fmt-maven-plugin version declared here.
-# XXX: Once GitHub actions uses Maven 3.9.2+, we can inline this variable with
-# version reference `${fmt.version}`, and `-Dfmt.version=2.21.1` added to
-# `shared_build_flags`.
-format_goal='com.spotify.fmt:fmt-maven-plugin:2.21.1:format'
-
-error_prone_shared_flags='-XepExcludedPaths:(\Q${project.basedir}${file.separator}src${file.separator}\E(it|test|xdocs-examples)\Q${file.separator}resources\E|\Q${project.build.directory}${file.separator}\E).*'
-
-error_prone_patch_flags="${error_prone_shared_flags} -XepPatchLocation:IN_PLACE -XepPatchChecks:$(
-   find "${error_prone_support_root}" \
-      -path "*/META-INF/services/com.google.errorprone.bugpatterns.BugChecker" \
-      -not -path "*/error-prone-experimental/*" \
-      -not -path "*/error-prone-guidelines/*" \
-      -print0 \
-    | xargs -0 "${grep_command}" -hoP '[^.]+$' \
-    | paste -s -d ',' -
-) ${patch_error_prone_flags}"
-
-error_prone_validation_flags="${error_prone_shared_flags} -XepDisableAllChecks $(
-   find "${error_prone_support_root}" \
-      -path "*/META-INF/services/com.google.errorprone.bugpatterns.BugChecker" \
-      -not -path "*/error-prone-experimental/*" \
-      -not -path "*/error-prone-guidelines/*" \
-      -print0 \
-    | xargs -0 "${grep_command}" -hoP '[^.]+$' \
-    | "${sed_command}" -r 's,(.*),-Xep:\1:WARN,' \
-    | paste -s -d ' ' -
-) ${validation_error_prone_flags}"
-
-echo "Shared build flags: ${shared_build_flags}"
-echo "Error Prone patch flags: ${error_prone_patch_flags}"
-echo "Error Prone validation flags: ${error_prone_validation_flags}"
-
-mkdir -p "${repos_root}"
-
-# Make sure that the targeted tag of the project's Git repository is checked
-# out.
-project_root="${repos_root}/${project}"
-if [ ! -d "${project_root}" ]; then
-  # The repository has not yet been cloned; create a shallow clone.
-  git clone --branch "${revision}" --depth 1 "${repository}" "${project_root}"
-else
-  # The repository does already appear to exist. Try to check out the requested
-  # tag if possible, and fetch it otherwise.
-  #
-  # Under certain circumstances this does not cause the relevant tag to be
-  # created, so if necessary we manually create it.
-  git -C "${project_root}" checkout --force "${revision}" 2>/dev/null \
-    || (
-         git -C "${project_root}" fetch --depth 1 "${repository}" "${revision}" \
-           && git -C "${project_root}" checkout --force FETCH_HEAD \
-           && (git -C "${project_root}" tag "${revision}" || true)
-       )
-fi
-
-pushd "${project_root}"
-
-# Make sure that Git is sufficiently configured to enable committing to the
-# project's Git repository.
-git config user.email || git config user.email 'integration-test@example.com'
-git config user.name || git config user.name 'Integration Test'
-
-# Prepare the code for analysis by (a) applying the minimal set of changes
-# required to run Error Prone with Error Prone Support and (b) formatting the
-# code using the same method by which it will be formatted after each
-# compilation round. The initial formatting operation ensures that subsequent
-# modifications can be rendered in a clean manner.
-git clean -fdx
-git apply < "${integration_test_root}/${test_name}-init.patch"
-git commit -m 'dependency: Introduce Error Prone Support' .
-mvn ${shared_build_flags} "${format_goal}"
-git commit -m 'minor: Reformat using Google Java Format' .
-diff_base="$(git rev-parse HEAD)"
-
-# Apply Error Prone Support-suggested changes until a fixed point is reached.
-function apply_patch() {
-  local extra_build_args="${1}"
-
-  mvn ${shared_build_flags} ${extra_build_args} \
-    package "${format_goal}" \
-    -Derror-prone.configuration-args="${error_prone_patch_flags}" \
-    -DskipTests
-
-  if ! git diff --exit-code; then
-    git commit -m 'minor: Apply patches' .
-
-    # Changes were applied, so another compilation round may apply yet more
-    # changes. For performance reasons we perform incremental compilation,
-    # enabled using a misleading flag. (See
-    # https://issues.apache.org/jira/browse/MCOMPILER-209 for details.)
-    apply_patch '-Dmaven.compiler.useIncrementalCompilation=false'
-  elif [ "${extra_build_args}" != 'clean' ]; then
-    # No changes were applied. We'll attempt one more round in which all files
-    # are recompiled, because there are cases in which violations are missed
-    # during incremental compilation.
-    apply_patch 'clean'
-  fi
-}
-apply_patch ''
-
-# Run one more full build and log the output.
-#
-# By also running the tests, we validate that the (majority of) applied changes
-# are behavior preserving.
-validation_build_log="${report_directory}/${test_name}-validation-build-log.txt"
-mvn ${shared_build_flags} \
-      clean package \
-      -Derror-prone.configuration-args="${error_prone_validation_flags}" \
-      ${validation_build_flags} \
-    | tee "${validation_build_log}" \
-  || failure=1
-
-# Collect the applied changes.
-expected_changes="${integration_test_root}/${test_name}-expected-changes.patch"
-actual_changes="${report_directory}/${test_name}-changes.patch"
-(git diff "${diff_base}"..HEAD | "${grep_command}" -vP '^(diff|index)' || true) > "${actual_changes}"
-
-# Collect the warnings reported by Error Prone Support checks.
-expected_warnings="${integration_test_root}/${test_name}-expected-warnings.txt"
-actual_warnings="${report_directory}/${test_name}-validation-build-warnings.txt"
-("${grep_command}" -oP "(?<=^\\Q[WARNING] ${PWD}/\\E).*" "${validation_build_log}" | "${grep_command}" -P '\] \[' || true) | LC_ALL=C sort > "${actual_warnings}"
-
-# Persist or validate the applied changes and reported warnings.
-if [ -n "${do_sync}" ]; then
-  echo 'Saving changes...'
-  cp "${actual_changes}" "${expected_changes}"
-  cp "${actual_warnings}" "${expected_warnings}"
-else
-  echo 'Inspecting changes...'
-  # XXX: This "diff of diffs" also contains vacuous sections, introduced due to
-  # line offset differences. Try to omit those from the final output.
-  if ! diff -u "${expected_changes}" "${actual_changes}"; then
-    echo 'There are unexpected changes. Inspect the preceding output for details.'
-    failure=1
-  fi
-  echo 'Inspecting emitted warnings...'
-  if ! diff -u "${expected_warnings}" "${actual_warnings}"; then
-    echo 'Diagnostics output changed. Inspect the preceding output for details.'
-    failure=1
-  fi
-fi
-
-if [ -n "${failure:-}" ]; then
-  exit 1
-fi

pom.xml

@@ -4,7 +4,7 @@
 
     <groupId>tech.picnic.error-prone-support</groupId>
     <artifactId>error-prone-support</artifactId>
-    <version>0.18.0</version>
+    <version>0.16.2-SNAPSHOT</version>
     <packaging>pom</packaging>
 
     <name>Picnic :: Error Prone Support</name>
@@ -48,11 +48,12 @@
         <module>refaster-runner</module>
         <module>refaster-support</module>
         <module>refaster-test-support</module>
+        <module>workshop</module>
     </modules>
 
     <scm child.scm.developerConnection.inherit.append.path="false" child.scm.url.inherit.append.path="false">
         <developerConnection>scm:git:git@github.com:PicnicSupermarket/error-prone-support.git</developerConnection>
-        <tag>v0.18.0</tag>
+        <tag>HEAD</tag>
         <url>https://github.com/PicnicSupermarket/error-prone-support</url>
     </scm>
     <issueManagement>
@@ -148,7 +149,7 @@
         <groupId.error-prone>com.google.errorprone</groupId.error-prone>
         <!-- The build timestamp is derived from the most recent commit
         timestamp in support of reproducible builds. -->
-        <project.build.outputTimestamp>2024-08-11T13:04:41Z</project.build.outputTimestamp>
+        <project.build.outputTimestamp>2024-03-15T12:04:44Z</project.build.outputTimestamp>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <!-- Glob pattern identifying Refaster rule definition files. These
         Java classes don't contain "regular" code, and thus require special
@@ -205,19 +206,19 @@
         one place. We use these to keep dependencies in sync. Version numbers
         that need to be referenced only once should *not* be listed here. -->
         <version.auto-service>1.1.1</version.auto-service>
-        <version.auto-value>1.11.0</version.auto-value>
+        <version.auto-value>1.10.4</version.auto-value>
         <version.error-prone>${version.error-prone-orig}</version.error-prone>
-        <version.error-prone-fork>v${version.error-prone-orig}-picnic-1</version.error-prone-fork>
-        <version.error-prone-orig>2.30.0</version.error-prone-orig>
-        <version.error-prone-slf4j>0.1.25</version.error-prone-slf4j>
+        <version.error-prone-fork>v${version.error-prone-orig}-picnic-2</version.error-prone-fork>
+        <version.error-prone-orig>2.26.1</version.error-prone-orig>
+        <version.error-prone-slf4j>0.1.23</version.error-prone-slf4j>
         <version.guava-beta-checker>1.0</version.guava-beta-checker>
         <version.jdk>17</version.jdk>
         <version.maven>3.9.5</version.maven>
-        <version.mockito>5.12.0</version.mockito>
+        <version.mockito>5.11.0</version.mockito>
         <version.nopen-checker>1.0.1</version.nopen-checker>
-        <version.nullaway>0.11.1</version.nullaway>
+        <version.nullaway>0.10.25</version.nullaway>
         <version.pitest-git>1.1.4</version.pitest-git>
-        <version.rewrite-templating>1.12.3</version.rewrite-templating>
+        <version.rewrite-templating>1.6.3</version.rewrite-templating>
         <version.surefire>3.2.3</version.surefire>
     </properties>
 
@@ -296,7 +297,7 @@
             <dependency>
                 <groupId>com.fasterxml.jackson</groupId>
                 <artifactId>jackson-bom</artifactId>
-                <version>2.17.2</version>
+                <version>2.17.0</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
@@ -328,7 +329,7 @@
             <dependency>
                 <groupId>com.google.googlejavaformat</groupId>
                 <artifactId>google-java-format</artifactId>
-                <version>1.23.0</version>
+                <version>1.22.0</version>
             </dependency>
             <dependency>
                 <groupId>com.google.guava</groupId>
@@ -338,14 +339,14 @@
             <dependency>
                 <groupId>com.google.guava</groupId>
                 <artifactId>guava-bom</artifactId>
-                <version>33.2.1-jre</version>
+                <version>33.1.0-jre</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
             <dependency>
                 <groupId>com.google.truth</groupId>
                 <artifactId>truth</artifactId>
-                <version>1.4.4</version>
+                <version>1.4.2</version>
             </dependency>
             <dependency>
                 <groupId>com.jakewharton.nopen</groupId>
@@ -360,7 +361,7 @@
             <dependency>
                 <groupId>io.projectreactor</groupId>
                 <artifactId>reactor-bom</artifactId>
-                <version>2023.0.8</version>
+                <version>2023.0.4</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
@@ -377,17 +378,12 @@
             <dependency>
                 <groupId>io.swagger.core.v3</groupId>
                 <artifactId>swagger-annotations</artifactId>
-                <version>2.2.22</version>
+                <version>2.2.21</version>
             </dependency>
             <dependency>
                 <groupId>jakarta.servlet</groupId>
                 <artifactId>jakarta.servlet-api</artifactId>
-                <version>6.1.0</version>
-            </dependency>
-            <dependency>
-                <groupId>javax.annotation</groupId>
-                <artifactId>javax.annotation-api</artifactId>
-                <version>1.3.2</version>
+                <version>6.0.0</version>
             </dependency>
             <dependency>
                 <groupId>javax.inject</groupId>
@@ -412,37 +408,29 @@
             <dependency>
                 <groupId>net.bytebuddy</groupId>
                 <artifactId>byte-buddy</artifactId>
-                <version>1.14.18</version>
-            </dependency>
-            <!-- Specified so that Renovate will file Maven upgrade PRs, which
-            subsequently will cause `maven-enforcer-plugin` to require that
-            developers build the project using the latest Maven release. -->
-            <dependency>
-                <groupId>org.apache.maven</groupId>
-                <artifactId>maven-plugin-api</artifactId>
-                <version>${version.maven}</version>
+                <version>1.14.13</version>
             </dependency>
             <dependency>
                 <groupId>org.aspectj</groupId>
                 <artifactId>aspectjweaver</artifactId>
-                <version>1.9.22.1</version>
+                <version>1.9.22</version>
             </dependency>
             <dependency>
                 <groupId>org.assertj</groupId>
                 <artifactId>assertj-bom</artifactId>
-                <version>3.26.3</version>
+                <version>3.25.3</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
             <dependency>
                 <groupId>org.checkerframework</groupId>
                 <artifactId>checker-qual</artifactId>
-                <version>3.46.0</version>
+                <version>3.42.0</version>
             </dependency>
             <dependency>
                 <groupId>org.hamcrest</groupId>
                 <artifactId>hamcrest-core</artifactId>
-                <version>3.0</version>
+                <version>2.2</version>
             </dependency>
             <dependency>
                 <groupId>org.immutables</groupId>
@@ -452,12 +440,12 @@
             <dependency>
                 <groupId>org.jspecify</groupId>
                 <artifactId>jspecify</artifactId>
-                <version>1.0.0</version>
+                <version>0.3.0</version>
             </dependency>
             <dependency>
                 <groupId>org.junit</groupId>
                 <artifactId>junit-bom</artifactId>
-                <version>5.10.3</version>
+                <version>5.10.2</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
@@ -471,7 +459,7 @@
             <dependency>
                 <groupId>org.mongodb</groupId>
                 <artifactId>mongodb-driver-core</artifactId>
-                <version>5.1.3</version>
+                <version>5.0.1</version>
             </dependency>
             <dependency>
                 <groupId>org.openrewrite</groupId>
@@ -481,40 +469,40 @@
             <dependency>
                 <groupId>org.openrewrite.recipe</groupId>
                 <artifactId>rewrite-recipe-bom</artifactId>
-                <version>2.16.0</version>
+                <version>2.8.1</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
             <dependency>
                 <groupId>org.slf4j</groupId>
                 <artifactId>slf4j-bom</artifactId>
-                <version>2.0.16</version>
+                <version>2.0.12</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
             <dependency>
                 <groupId>org.springframework</groupId>
                 <artifactId>spring-framework-bom</artifactId>
-                <version>6.1.11</version>
+                <version>6.1.5</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
             <dependency>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-test</artifactId>
-                <version>3.3.2</version>
+                <version>3.2.4</version>
             </dependency>
             <dependency>
                 <groupId>org.springframework.security</groupId>
                 <artifactId>spring-security-bom</artifactId>
-                <version>6.3.1</version>
+                <version>6.2.3</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
             <dependency>
                 <groupId>org.testng</groupId>
                 <artifactId>testng</artifactId>
-                <version>7.10.2</version>
+                <version>7.9.0</version>
             </dependency>
         </dependencies>
     </dependencyManagement>
@@ -525,7 +513,7 @@
                 <plugin>
                     <groupId>com.github.ekryd.sortpom</groupId>
                     <artifactId>sortpom-maven-plugin</artifactId>
-                    <version>4.0.0</version>
+                    <version>3.4.1</version>
                     <configuration>
                         <createBackupFile>false</createBackupFile>
                         <encoding>${project.build.sourceEncoding}</encoding>
@@ -629,7 +617,7 @@
                 <plugin>
                     <groupId>io.github.git-commit-id</groupId>
                     <artifactId>git-commit-id-maven-plugin</artifactId>
-                    <version>9.0.1</version>
+                    <version>8.0.2</version>
                     <configuration>
                         <injectAllReactorProjects>true</injectAllReactorProjects>
                         <runOnlyOnce>true</runOnlyOnce>
@@ -648,7 +636,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-checkstyle-plugin</artifactId>
-                    <version>3.4.0</version>
+                    <version>3.3.1</version>
                     <configuration>
                         <checkstyleRules>
                             <!-- We only enable rules that are not enforced by
@@ -684,7 +672,6 @@
                                         <property name="allowNonPrintableEscapes" value="true" />
                                     </module>
                                     <module name="AvoidNoArgumentSuperConstructorCall" />
-                                    <module name="ConstructorsDeclarationGrouping" />
                                     <module name="DeclarationOrder">
                                         <!-- We don't enforce sorting fields by
                                         their visibility modifier, for two
@@ -897,7 +884,7 @@
                         <dependency>
                             <groupId>com.puppycrawl.tools</groupId>
                             <artifactId>checkstyle</artifactId>
-                            <version>10.17.0</version>
+                            <version>10.15.0</version>
                         </dependency>
                         <dependency>
                             <groupId>io.spring.nohttp</groupId>
@@ -917,7 +904,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-clean-plugin</artifactId>
-                    <version>3.4.0</version>
+                    <version>3.3.2</version>
                 </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
@@ -965,43 +952,11 @@
                         https://issues.apache.org/jira/browse/MCOMPILER-209. -->
                         <useIncrementalCompilation>false</useIncrementalCompilation>
                     </configuration>
-                    <executions>
-                        <!-- OpenRewrite recipe sources, generated by the
-                        `rewrite-templating` annotation processor and
-                        identified as classes whose name ends in `Recipes`, are
-                        compiled to target Java 8 for compatibility with the
-                        wider OpenRewrite ecosystem. The `maven-jar-plugin` is
-                        configured to package these files into a separate JAR. -->
-                        <execution>
-                            <id>compile-recipes</id>
-                            <goals>
-                                <goal>compile</goal>
-                            </goals>
-                            <configuration>
-                                <compilerArgs combine.self="override">
-                                    <!-- When Java 8 is targeted we can't use
-                                    the `add-exports` flag. And since this goal
-                                    only recompiles already-compiled code,
-                                    static analysis is irrelevant. As such we
-                                    clear all compiler arguments, and only
-                                    suppress source/target/bootstrap classpath
-                                    warnings. -->
-                                    <arg>-Xlint:-options</arg>
-                                </compilerArgs>
-                                <source>8</source>
-                                <target>8</target>
-                                <includes>
-                                    <include>**/*Recipes.java</include>
-                                </includes>
-                                <outputDirectory>${project.build.directory}/openrewrite-recipes</outputDirectory>
-                            </configuration>
-                        </execution>
-                    </executions>
                 </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-dependency-plugin</artifactId>
-                    <version>3.7.1</version>
+                    <version>3.6.1</version>
                     <configuration>
                         <!-- XXX: Drop `ignoreAllNonTestScoped` once
                         https://issues.apache.org/jira/browse/MNG-6058 is
@@ -1016,7 +971,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-deploy-plugin</artifactId>
-                    <version>3.1.2</version>
+                    <version>3.1.1</version>
                     <configuration>
                         <retryFailedDeploymentCount>3</retryFailedDeploymentCount>
                     </configuration>
@@ -1024,7 +979,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-enforcer-plugin</artifactId>
-                    <version>3.5.0</version>
+                    <version>3.4.1</version>
                     <configuration>
                         <fail>false</fail>
                         <rules>
@@ -1079,12 +1034,6 @@
                             <requireJavaVersion>
                                 <version>${version.jdk}</version>
                             </requireJavaVersion>
-                            <requireMatchingCoordinates>
-                                <moduleNameMustMatchArtifactId>true</moduleNameMustMatchArtifactId>
-                            </requireMatchingCoordinates>
-                            <requireMavenVersion>
-                                <version>${version.maven}</version>
-                            </requireMavenVersion>
                             <requireNoRepositories />
                             <requirePluginVersions />
                             <requireUpperBoundDeps />
@@ -1109,7 +1058,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-gpg-plugin</artifactId>
-                    <version>3.2.4</version>
+                    <version>3.2.2</version>
                     <executions>
                         <execution>
                             <id>sign-artifacts</id>
@@ -1122,12 +1071,12 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-install-plugin</artifactId>
-                    <version>3.1.2</version>
+                    <version>3.1.1</version>
                 </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-jar-plugin</artifactId>
-                    <version>3.4.2</version>
+                    <version>3.3.0</version>
                     <configuration>
                         <skipIfEmpty>true</skipIfEmpty>
                         <archive>
@@ -1144,39 +1093,6 @@
                         </archive>
                     </configuration>
                     <executions>
-                        <execution>
-                            <id>default-jar</id>
-                            <goals>
-                                <goal>jar</goal>
-                            </goals>
-                            <configuration>
-                                <!-- These Java 17 bytecode classes are omitted
-                                from the default JAR, as instead we produce a
-                                separate artifact with Java 8 bytecode variants. -->
-                                <excludes>
-                                    <excludes>**/*Recipe$*.class</excludes>
-                                    <excludes>**/*Recipe.class</excludes>
-                                    <excludes>**/*Recipes.class</excludes>
-                                </excludes>
-                            </configuration>
-                        </execution>
-                        <execution>
-                            <!-- Creates a custom JAR with Java 8-compatible
-                            OpenRewrite recipe classes. -->
-                            <id>create-openrewrite-recipes-jar</id>
-                            <goals>
-                                <goal>jar</goal>
-                            </goals>
-                            <configuration>
-                                <classesDirectory>${project.build.directory}/openrewrite-recipes</classesDirectory>
-                                <classifier>recipes</classifier>
-                                <includes>
-                                    <includes>**/*Recipe$*.class</includes>
-                                    <includes>**/*Recipe.class</includes>
-                                    <includes>**/*Recipes.class</includes>
-                                </includes>
-                            </configuration>
-                        </execution>
                         <execution>
                             <id>create-test-jar</id>
                             <goals>
@@ -1188,7 +1104,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-javadoc-plugin</artifactId>
-                    <version>3.8.0</version>
+                    <version>3.6.3</version>
                     <configuration>
                         <additionalJOptions>
                             <additionalJOption>--add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED</additionalJOption>
@@ -1217,7 +1133,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-release-plugin</artifactId>
-                    <version>3.1.1</version>
+                    <version>3.0.1</version>
                     <configuration>
                         <autoVersionSubmodules>true</autoVersionSubmodules>
                         <preparationProfiles>release</preparationProfiles>
@@ -1244,7 +1160,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-source-plugin</artifactId>
-                    <version>3.3.1</version>
+                    <version>3.3.0</version>
                     <executions>
                         <execution>
                             <id>generate-source-jar</id>
@@ -1258,7 +1174,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-surefire-plugin</artifactId>
-                    <version>3.3.1</version>
+                    <version>3.2.5</version>
                     <configuration>
                         <includes>
                             <include>**/*Test.java</include>
@@ -1274,7 +1190,7 @@
                 <plugin>
                     <groupId>org.codehaus.mojo</groupId>
                     <artifactId>build-helper-maven-plugin</artifactId>
-                    <version>3.6.0</version>
+                    <version>3.5.0</version>
                 </plugin>
                 <plugin>
                     <groupId>org.codehaus.mojo</groupId>
@@ -1370,7 +1286,6 @@
                                 <!-- -->
                                 GPL-2.0-with-classpath-exception
                                 | CDDL/GPLv2+CE
-                                | CDDL + GPLv2 with classpath exception
                                 | GNU General Public License, version 2 (GPL2), with the classpath exception
                                 | GNU General Public License, version 2, with the Classpath Exception
                                 | GPL2 w/ CPE
@@ -1405,7 +1320,7 @@
                 <plugin>
                     <groupId>org.codehaus.mojo</groupId>
                     <artifactId>tidy-maven-plugin</artifactId>
-                    <version>1.3.0</version>
+                    <version>1.2.0</version>
                     <executions>
                         <execution>
                             <id>check-pom</id>
@@ -1418,7 +1333,7 @@
                 <plugin>
                     <groupId>org.codehaus.mojo</groupId>
                     <artifactId>versions-maven-plugin</artifactId>
-                    <version>2.17.1</version>
+                    <version>2.16.2</version>
                     <configuration>
                         <updateBuildOutputTimestampPolicy>never</updateBuildOutputTimestampPolicy>
                     </configuration>
@@ -1426,7 +1341,7 @@
                 <plugin>
                     <groupId>org.gaul</groupId>
                     <artifactId>modernizer-maven-plugin</artifactId>
-                    <version>2.9.0</version>
+                    <version>2.8.0</version>
                     <configuration>
                         <exclusionPatterns>
                             <!-- The plugin suggests replacing usages of
@@ -1487,7 +1402,7 @@
                 <plugin>
                     <groupId>org.pitest</groupId>
                     <artifactId>pitest-maven</artifactId>
-                    <version>1.16.1</version>
+                    <version>1.15.8</version>
                     <configuration>
                         <excludedClasses>
                             <!-- AutoValue generated classes. -->
@@ -1541,7 +1456,7 @@
                 <plugin>
                     <groupId>org.sonarsource.scanner.maven</groupId>
                     <artifactId>sonar-maven-plugin</artifactId>
-                    <version>4.0.0.4121</version>
+                    <version>3.11.0.3922</version>
                 </plugin>
             </plugins>
         </pluginManagement>

refaster-compiler/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.18.0</version>
+        <version>0.16.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-compiler</artifactId>

refaster-compiler/src/main/java/tech/picnic/errorprone/refaster/plugin/RefasterRuleCompilerTaskListener.java

@@ -21,6 +21,7 @@ import com.sun.tools.javac.code.Symbol.ClassSymbol;
 import com.sun.tools.javac.code.Symbol.PackageSymbol;
 import com.sun.tools.javac.main.JavaCompiler;
 import com.sun.tools.javac.util.Context;
+import com.sun.tools.javac.util.Name;
 import java.io.IOException;
 import java.io.ObjectOutput;
 import java.io.ObjectOutputStream;
@@ -111,7 +112,7 @@ final class RefasterRuleCompilerTaskListener implements TaskListener {
             return (sym != null
                     && sym.getQualifiedName()
                         .contentEquals(BeforeTemplate.class.getCanonicalName()))
-                || super.visitAnnotation(node, null);
+                || super.visitAnnotation(node, unused);
           }
 
           @Override
@@ -136,10 +137,10 @@ final class RefasterRuleCompilerTaskListener implements TaskListener {
     return enclosingPackage == null ? "" : enclosingPackage.toString();
   }
 
-  private static String toSimpleFlatName(ClassSymbol symbol) {
-    String flatName = symbol.flatName().toString();
+  private static CharSequence toSimpleFlatName(ClassSymbol symbol) {
+    Name flatName = symbol.flatName();
     int lastDot = flatName.lastIndexOf((byte) '.');
-    return lastDot < 0 ? flatName : flatName.substring(lastDot + 1);
+    return lastDot < 0 ? flatName : flatName.subSequence(lastDot + 1, flatName.length());
   }
 
   private static void outputCodeTransformer(CodeTransformer codeTransformer, FileObject target)

refaster-runner/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.18.0</version>
+        <version>0.16.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-runner</artifactId>
@@ -58,11 +58,6 @@
             <artifactId>guava</artifactId>
             <scope>provided</scope>
         </dependency>
-        <dependency>
-            <groupId>javax.annotation</groupId>
-            <artifactId>javax.annotation-api</artifactId>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>javax.inject</groupId>
             <artifactId>javax.inject</artifactId>

refaster-support/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.18.0</version>
+        <version>0.16.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-support</artifactId>

refaster-test-support/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.18.0</version>
+        <version>0.16.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-test-support</artifactId>
@@ -50,11 +50,6 @@
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
         </dependency>
-        <dependency>
-            <groupId>javax.annotation</groupId>
-            <artifactId>javax.annotation-api</artifactId>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>javax.inject</groupId>
             <artifactId>javax.inject</artifactId>

refaster-test-support/src/main/java/tech/picnic/errorprone/refaster/test/RefasterRuleCollection.java

@@ -319,7 +319,7 @@ public final class RefasterRuleCollection extends BugChecker implements Compilat
       return indexedMatches.subRangeMap(Range.closedOpen(startPosition, endPosition));
     }
 
-    private static ImmutableListMultimap<Long, String> getUnexpectedMatchesByLineNumber(
+    private ImmutableListMultimap<Long, String> getUnexpectedMatchesByLineNumber(
         ImmutableRangeMap<Integer, String> matches, String ruleUnderTest, VisitorState state) {
       LineMap lineMap = state.getPath().getCompilationUnit().getLineMap();
       return matches.asMapOfRanges().entrySet().stream()

website/_data/compatibility.yml

@@ -3,12 +3,6 @@
 releases:
   - version: 0.16.1
     compatible:
-      - "2.29.2"
-      - "2.29.1"
-      - "2.29.0"
-      - "2.28.0"
-      - "2.27.1"
-      - "2.27.0"
       - "2.26.1"
       - "2.26.0"
       - "2.25.0"
@@ -17,12 +11,6 @@ releases:
       - "2.23.0"
   - version: 0.16.0
     compatible:
-      - "2.29.2"
-      - "2.29.1"
-      - "2.29.0"
-      - "2.28.0"
-      - "2.27.1"
-      - "2.27.0"
       - "2.26.1"
       - "2.26.0"
       - "2.25.0"
@@ -31,12 +19,6 @@ releases:
       - "2.23.0"
   - version: 0.15.0
     compatible:
-      - "2.29.2"
-      - "2.29.1"
-      - "2.29.0"
-      - "2.28.0"
-      - "2.27.1"
-      - "2.27.0"
       - "2.26.1"
       - "2.26.0"
       - "2.25.0"
@@ -45,12 +27,6 @@ releases:
       - "2.23.0"
   - version: 0.14.0
     compatible:
-      - "2.29.2"
-      - "2.29.1"
-      - "2.29.0"
-      - "2.28.0"
-      - "2.27.1"
-      - "2.27.0"
       - "2.26.1"
       - "2.26.0"
       - "2.25.0"

workshop/README.md

@@ -0,0 +1,108 @@
+# Error Prone Workshop
+
+XXX: @Rick update the slides.
+
+## Initial setup of the workshop
+
+1. Start by cloning this repository locally from GitHub.
+2. Checkout the `workshop` branch.
+3. Make sure to run `mvn clean install` in the root of this repository.
+4. Open your code editor and familiarize yourself with the project structure.
+
+In IntelliJ IDEA (or your preferred editor), try to run the
+`WorkshopRefasterRulesTest` test. You might see the following error:
+
+```
+java: exporting a package from system module jdk.compiler is not allowed with --release
+```
+
+If this happens, go to _Settings -> Build, Execution, Deployment -> Compiler ->
+Java Compiler_ and deselect the option _Use '--release' option for
+cross-compilation (Java 9 and later)_.
+
+Now the project is ready for the workshop.
+
+## Part 1: Writing Refaster rules
+
+During this part of the workshop we will implement multiple Refaster rules.
+
+Go to the `workshop` module and open the
+`tech.picnic.errorprone.workshop.refasterrules` package. There you can find one
+example and 5 different exercises to do. Make sure to check out the
+`WorkshopRefasterRulesTest.java` class where you can enable tests. Per
+assignment there is a test in this class that one can enable (by dropping the
+`@Disabled` annotation) to validate your changes. The goal is to implement or
+improve the Refaster rules such that the enabled tests pass.
+
+Tips:
+
+* Go through the exercises in the proposed order.
+* The `XXX:` comments explains what needs to happen.
+* See the test cases for each Refaster rule by looking for the name of the
+  Refaster rule prefixed with `test`. For example, the
+  `WorkshopAssignment0Rules.java` rule collection has a Refaster rule named
+  `ExampleStringIsEmpty`. In the `WorkshopAssignment0RulesTestInput.java` and
+  `WorkshopAssignment0RulesTestOutput.java` files there is a
+  `testExampleStringIsEmpty` method that shows the input and output to test the
+  Refaster rule.
+
+## Part 2: Writing Error Prone checks
+
+During this part of the workshop we will implement parts of multiple Error
+Prone `BugChecker`s. Each of these classes contain `XXX` comments explaining
+what needs to be implemented. However, before diving in, make sure to first
+navigate to a check's associated test class to drop the class-level `@Disabled`
+annotation. Upon initial execution the tests will fail; the goal is to get then
+to pass.
+
+Some utility classes that you can use:
+
+* `com.google.errorprone.util.ASTHelpers`: contains many common operations on
+  the Abstract Syntax Tree.
+* `com.google.errorprone.fixes.SuggestedFixes`: contains helper methods for
+  creating `Fix`es.
+
+To see the impact of the newly introduced Error Prone checks [re-trigger the
+integration test framework](#validating-changes-with-the-integration-tests).
+
+## Part 3 (optional): Validating changes with the integration tests
+
+We created an integration testing framework that allows us to see the impact of
+the rules that are created. This testing framework can be executed locally and
+via GitHub Actions.
+
+If you still have more than 10-15 minutes left, and you want to test this
+locally, run the following commands:
+
+```sh
+mvn clean install -DskipTests -Dverification.skip
+./integration-tests/checkstyle-10.12.4.sh
+```
+
+Once the process is complete, and changes are introduced, the following output
+will be printed:
+
+```
+There are unexpected changes.
+Inspect the changes here: /tmp/tmp.Cmr423L1pA/checkstyle-10.12.4-diff-of-diffs-changes.patch
+```
+
+This file is be provided for your review using your preferred text editor.
+Alternatively, you can also navigate to the repository by going to the
+`./integration-tests/.repos/checkstyle` directory and executing `git log -p` to
+view the commit history and associated changes.
+
+This shows the impact of the rules that you wrote when they are applied to
+Checkstyle!
+
+The other option is to execute the integration test via GitHub Actions. You
+only need to commit and push to the branch. This will trigger execution of the
+integration tests, which will run for about 10 minutes. When the build is
+finished, go to the _Actions_ tab in your fork and navigate to your most recent
+commit and click on it. Then click on _Summary_ and download the artifact
+`integration-test-checkstyle-10.12.4` at the bottom. Once done, unzip the
+artifact and inspect the `checkstyle-10.12.4-diff-of-diffs-changes.patch` file
+to see the changes.
+
+[eps-github]: https://github.com/PicnicSupermarket/error-prone-support
+[eps-workshop-jfall]: https://drive.google.com/file/d/1Es1OuSUmPHSt3BjeCWfrXfoF-cJkkA1A/view

workshop/pom.xml

@@ -0,0 +1,150 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>tech.picnic.error-prone-support</groupId>
+        <artifactId>error-prone-support</artifactId>
+        <version>0.16.2-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>workshop</artifactId>
+
+    <name>Picnic :: Error Prone Support :: Workshop</name>
+    <description>Project for the Error Prone Workshop.</description>
+    <url>https://error-prone.picnic.tech</url>
+
+    <dependencies>
+        <dependency>
+            <groupId>${groupId.error-prone}</groupId>
+            <artifactId>error_prone_annotation</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>${groupId.error-prone}</groupId>
+            <artifactId>error_prone_annotations</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>${groupId.error-prone}</groupId>
+            <artifactId>error_prone_check_api</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>${groupId.error-prone}</groupId>
+            <artifactId>error_prone_core</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>${groupId.error-prone}</groupId>
+            <artifactId>error_prone_test_helpers</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>error-prone-utils</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>refaster-compiler</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>refaster-support</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>refaster-test-support</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.auto.service</groupId>
+            <artifactId>auto-service-annotations</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.aspectj</groupId>
+            <artifactId>aspectjweaver</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.openrewrite</groupId>
+            <artifactId>rewrite-core</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.openrewrite</groupId>
+            <artifactId>rewrite-java</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.openrewrite</groupId>
+            <artifactId>rewrite-java-11</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.openrewrite</groupId>
+            <artifactId>rewrite-templating</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-context</artifactId>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <pluginManagement>
+            <plugins>
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-compiler-plugin</artifactId>
+                    <configuration>
+                        <annotationProcessorPaths combine.children="append">
+                            <path>
+                                <groupId>${project.groupId}</groupId>
+                                <artifactId>refaster-compiler</artifactId>
+                                <version>${project.version}</version>
+                            </path>
+                            <path>
+                                <groupId>${project.groupId}</groupId>
+                                <artifactId>refaster-support</artifactId>
+                                <version>${project.version}</version>
+                            </path>
+                        </annotationProcessorPaths>
+                        <compilerArgs combine.children="append">
+                            <arg>-Xplugin:RefasterRuleCompiler</arg>
+                        </compilerArgs>
+                    </configuration>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+    </build>
+</project>

workshop/src/main/java/tech/picnic/errorprone/workshop/bugpatterns/Assignment0DeleteEmptyMethod.java

@@ -0,0 +1,33 @@
+package tech.picnic.errorprone.workshop.bugpatterns;
+
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.sun.source.tree.MethodTree;
+
+/** A {@link BugChecker} that flags empty methods that seemingly can simply be deleted. */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Empty method can likely be deleted",
+    severity = WARNING,
+    tags = SIMPLIFICATION)
+public final class Assignment0DeleteEmptyMethod extends BugChecker implements MethodTreeMatcher {
+  private static final long serialVersionUID = 1L;
+
+  /** Instantiates a new {@link Assignment0DeleteEmptyMethod} instance. */
+  public Assignment0DeleteEmptyMethod() {}
+
+  @Override
+  public Description matchMethod(MethodTree tree, VisitorState state) {
+    // XXX: Part 1: Ensure that we only delete methods that contain no statements.
+    // XXX: Part 2: Don't delete methods that are annotated with `@Override`.
+
+    return Description.NO_MATCH;
+  }
+}

workshop/src/main/java/tech/picnic/errorprone/workshop/bugpatterns/Assignment1AssertJIsNullMethod.java

@@ -0,0 +1,61 @@
+package tech.picnic.errorprone.workshop.bugpatterns;
+
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.Matchers.allOf;
+import static com.google.errorprone.matchers.Matchers.argument;
+import static com.google.errorprone.matchers.Matchers.argumentCount;
+import static com.google.errorprone.matchers.Matchers.instanceMethod;
+import static com.google.errorprone.matchers.Matchers.nullLiteral;
+
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.MethodInvocationTree;
+
+/**
+ * A {@link BugChecker} that flags AssertJ {@code isEqualTo(null)} checks for simplification.
+ *
+ * <p>This bug checker cannot be replaced with a simple Refaster rule, as the Refaster approach
+ * would require that all overloads of {@link org.assertj.core.api.Assert#isEqualTo(Object)} (such
+ * as {@link org.assertj.core.api.AbstractStringAssert#isEqualTo(String)}) are explicitly
+ * enumerated. This bug checker generically matches all such current and future overloads.
+ */
+@BugPattern(
+    summary = "Prefer `.isNull()` over `.isEqualTo(null)`",
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class Assignment1AssertJIsNullMethod extends BugChecker
+    implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<MethodInvocationTree> ASSERT_IS_EQUAL_TO_NULL =
+      allOf(
+          instanceMethod().onDescendantOf("org.assertj.core.api.Assert").named("isEqualTo"),
+          argumentCount(1),
+          argument(0, nullLiteral()));
+
+  /** Instantiates a new {@link Assignment1AssertJIsNullMethod} instance. */
+  public Assignment1AssertJIsNullMethod() {}
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    // This statement filters out `MethodInvocation`s that are *not* `assertThat().isEqualTo(null)`
+    // statements.
+    if (!ASSERT_IS_EQUAL_TO_NULL.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    SuggestedFix.Builder fix = SuggestedFix.builder();
+
+    // XXX: Using `fix.merge(<some code>);` make sure we rename the method invocation to `isNull`.
+    // See the `SuggestedFixes` class ;).
+
+    tree.getArguments().forEach(arg -> fix.merge(SuggestedFix.delete(arg)));
+
+    return describeMatch(tree, fix.build());
+  }
+}

workshop/src/main/java/tech/picnic/errorprone/workshop/bugpatterns/Assignment2DropMockitoEq.java

@@ -0,0 +1,56 @@
+package tech.picnic.errorprone.workshop.bugpatterns;
+
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.Matchers.staticMethod;
+
+import com.google.common.collect.Iterables;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import tech.picnic.errorprone.utils.SourceCode;
+
+/**
+ * A {@link BugChecker} that flags method invocations for which all arguments are wrapped using
+ * {@link org.mockito.Mockito#eq}; this is redundant.
+ */
+@BugPattern(
+    summary = "Don't unnecessarily use Mockito's `eq(...)`",
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class Assignment2DropMockitoEq extends BugChecker
+    implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> MOCKITO_EQ_METHOD =
+      staticMethod().onClass("org.mockito.ArgumentMatchers").named("eq");
+
+  /** Instantiates a new {@link Assignment2DropMockitoEq} instance. */
+  public Assignment2DropMockitoEq() {}
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    // XXX: Make sure to return `Description.NO_MATCH` if the `tree` doesn't have arguments, or if
+    // the `isEqInvocation` method below returns `false` for at least one of the arguments.
+
+    SuggestedFix.Builder suggestedFix = SuggestedFix.builder();
+    for (ExpressionTree arg : tree.getArguments()) {
+      suggestedFix.replace(
+          arg,
+          SourceCode.treeToString(
+              Iterables.getOnlyElement(((MethodInvocationTree) arg).getArguments()), state));
+    }
+
+    return describeMatch(tree, suggestedFix.build());
+  }
+
+  @SuppressWarnings("UnusedMethod" /* Recommended to use when implementing this assignment. */)
+  private static boolean isEqInvocation(ExpressionTree tree, VisitorState state) {
+    return tree instanceof MethodInvocationTree && MOCKITO_EQ_METHOD.matches(tree, state);
+  }
+}

workshop/src/main/java/tech/picnic/errorprone/workshop/bugpatterns/Assignment3DropAutowiredConstructorAnnotation.java

@@ -0,0 +1,54 @@
+package tech.picnic.errorprone.workshop.bugpatterns;
+
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
+import static com.google.errorprone.matchers.Matchers.annotations;
+import static com.google.errorprone.matchers.Matchers.isType;
+
+import com.google.common.collect.Iterables;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.ClassTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.MultiMatcher;
+import com.google.errorprone.matchers.MultiMatcher.MultiMatchResult;
+import com.sun.source.tree.AnnotationTree;
+import com.sun.source.tree.ClassTree;
+import com.sun.source.tree.MethodTree;
+import com.sun.source.tree.Tree;
+import java.util.ArrayList;
+import java.util.List;
+import tech.picnic.errorprone.utils.SourceCode;
+
+/** A {@link BugChecker} that flags redundant {@code @Autowired} constructor annotations. */
+@BugPattern(
+    summary = "Omit `@Autowired` on a class' sole constructor, as it is redundant",
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class Assignment3DropAutowiredConstructorAnnotation extends BugChecker
+    implements ClassTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final MultiMatcher<Tree, AnnotationTree> AUTOWIRED_ANNOTATION =
+      annotations(AT_LEAST_ONE, isType("org.springframework.beans.factory.annotation.Autowired"));
+
+  /** Instantiates a new {@link Assignment3DropAutowiredConstructorAnnotation} instance. */
+  public Assignment3DropAutowiredConstructorAnnotation() {}
+
+  @Override
+  public Description matchClass(ClassTree tree, VisitorState state) {
+    // XXX: Using the `ASTHelpers#getConstructors` method, return `Description.NO_MATCH` if we do
+    // not have exactly 1 constructor (start by dropping `new ArrayList<>()` on the next line).
+    List<MethodTree> constructors = new ArrayList<>();
+
+    MultiMatchResult<AnnotationTree> hasAutowiredAnnotation =
+        AUTOWIRED_ANNOTATION.multiMatchResult(Iterables.getOnlyElement(constructors), state);
+    if (!hasAutowiredAnnotation.matches()) {
+      return Description.NO_MATCH;
+    }
+
+    AnnotationTree annotation = hasAutowiredAnnotation.onlyMatchingNode();
+    return describeMatch(annotation, SourceCode.deleteWithTrailingWhitespace(annotation, state));
+  }
+}

workshop/src/main/java/tech/picnic/errorprone/workshop/bugpatterns/Assignment4JUnitTestMethodDeclaration.java

@@ -0,0 +1,61 @@
+package tech.picnic.errorprone.workshop.bugpatterns;
+
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
+import static com.google.errorprone.matchers.Matchers.annotations;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.isType;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.MultiMatcher;
+import com.sun.source.tree.AnnotationTree;
+import com.sun.source.tree.MethodTree;
+import javax.lang.model.element.Modifier;
+
+/** A {@link BugChecker} that flags non-canonical JUnit method declarations. */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "JUnit method declaration can likely be improved",
+    severity = WARNING,
+    tags = SIMPLIFICATION)
+@SuppressWarnings({
+  "UnusedMethod",
+  "UnusedVariable"
+} /* This check is yet to be implemented as part of the demo. */)
+public final class Assignment4JUnitTestMethodDeclaration extends BugChecker
+    implements MethodTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final ImmutableSet<Modifier> ILLEGAL_MODIFIERS =
+      Sets.immutableEnumSet(Modifier.PRIVATE, Modifier.PROTECTED, Modifier.PUBLIC);
+  private static final MultiMatcher<MethodTree, AnnotationTree> TEST_METHOD =
+      annotations(AT_LEAST_ONE, anyOf(isType("org.junit.jupiter.api.Test")));
+
+  /** Instantiates a new {@link Assignment4JUnitTestMethodDeclaration} instance. */
+  public Assignment4JUnitTestMethodDeclaration() {}
+
+  @Override
+  public Description matchMethod(MethodTree tree, VisitorState state) {
+    // XXX: Part 1: Return `Description.NO_MATCH` if the method is not a `TEST_METHOD`.
+
+    SuggestedFix.Builder fixBuilder = SuggestedFix.builder();
+
+    // XXX: Part 2: Make sure that JUnit test methods don't use any of the modifiers from the
+    // `ILLEGAL_MODIFIERS` field, by using `SuggestedFixes#removeModifiers` and
+    // `SuggestedFix.Builder#merge`.
+
+    if (fixBuilder.isEmpty()) {
+      return Description.NO_MATCH;
+    }
+
+    return describeMatch(tree, fixBuilder.build());
+  }
+}

workshop/src/main/java/tech/picnic/errorprone/workshop/bugpatterns/Assignment5DeleteIdentityConversion.java

@@ -0,0 +1,108 @@
+package tech.picnic.errorprone.workshop.bugpatterns;
+
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.staticMethod;
+import static com.google.errorprone.suppliers.Suppliers.OBJECT_TYPE;
+
+import com.google.common.primitives.Primitives;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.bugpatterns.TypesWithUndefinedEquality;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.google.errorprone.util.ASTHelpers.TargetType;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MemberSelectTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.tools.javac.code.Type;
+import com.sun.tools.javac.code.Types;
+import java.util.Arrays;
+import java.util.List;
+
+/** A {@link BugChecker} that flags redundant identity conversions. */
+@BugPattern(
+    summary = "Avoid or clarify identity conversions",
+    severity = WARNING,
+    tags = SIMPLIFICATION)
+public final class Assignment5DeleteIdentityConversion extends BugChecker
+    implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> IS_CONVERSION_METHOD =
+      anyOf(
+          staticMethod()
+              .onClassAny(
+                  Primitives.allWrapperTypes().stream()
+                      .map(Class::getName)
+                      .collect(toImmutableSet()))
+              .named("valueOf"),
+          staticMethod().onClass(String.class.getName()).named("valueOf"),
+          staticMethod()
+              .onClassAny(
+                  "com.google.common.collect.ImmutableBiMap",
+                  "com.google.common.collect.ImmutableList",
+                  "com.google.common.collect.ImmutableListMultimap",
+                  "com.google.common.collect.ImmutableMap",
+                  "com.google.common.collect.ImmutableMultimap",
+                  "com.google.common.collect.ImmutableMultiset",
+                  "com.google.common.collect.ImmutableRangeMap",
+                  "com.google.common.collect.ImmutableRangeSet",
+                  "com.google.common.collect.ImmutableSet",
+                  "com.google.common.collect.ImmutableSetMultimap",
+                  "com.google.common.collect.ImmutableTable")
+              .named("copyOf"),
+          staticMethod()
+              .onClass("com.google.errorprone.matchers.Matchers")
+              .namedAnyOf("allOf", "anyOf"));
+
+  /** Instantiates a new {@link Assignment5DeleteIdentityConversion} instance. */
+  public Assignment5DeleteIdentityConversion() {}
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    List<? extends ExpressionTree> arguments = tree.getArguments();
+    // XXX: Make sure we skip invocations that do not pass exactly one argument, by using the
+    // `tree`.
+    if (!IS_CONVERSION_METHOD.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    ExpressionTree sourceTree = arguments.get(0);
+    Type sourceType = ASTHelpers.getType(sourceTree);
+    Type resultType = ASTHelpers.getType(tree);
+    TargetType targetType = ASTHelpers.targetType(state);
+    if (sourceType == null || resultType == null || targetType == null) {
+      return Description.NO_MATCH;
+    }
+
+    if (!state.getTypes().isSameType(sourceType, resultType)
+        && !isConvertibleWithWellDefinedEquality(sourceType, targetType.type(), state)) {
+      return Description.NO_MATCH;
+    }
+
+    if (sourceType.isPrimitive()
+        && state.getPath().getParentPath().getLeaf() instanceof MemberSelectTree) {
+      return Description.NO_MATCH;
+    }
+
+    return buildDescription(tree)
+        // XXX: Use the `.addFix()` to suggest replacing the original `tree` with the `sourceTree`.
+        // Tip: You can get the actual String representation of a Tree by using the
+        // `SourceCode#treeToString`.
+        .build();
+  }
+
+  private static boolean isConvertibleWithWellDefinedEquality(
+      Type sourceType, Type targetType, VisitorState state) {
+    Types types = state.getTypes();
+    return !types.isSameType(targetType, OBJECT_TYPE.get(state))
+        && types.isConvertible(sourceType, targetType)
+        && Arrays.stream(TypesWithUndefinedEquality.values())
+            .noneMatch(b -> b.matchesType(sourceType, state) || b.matchesType(targetType, state));
+  }
+}

workshop/src/main/java/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment0Rules.java

@@ -0,0 +1,22 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+
+/** Refaster rule used as example for the assignments of the workshop. */
+final class WorkshopAssignment0Rules {
+  private WorkshopAssignment0Rules() {}
+
+  /** Prefer {@link String#isEmpty()} over alternatives that consult the string's length. */
+  static final class ExampleStringIsEmpty {
+    @BeforeTemplate
+    static boolean before(String string) {
+      return string.length() == 0;
+    }
+
+    @AfterTemplate
+    static boolean after(String string) {
+      return string.isEmpty();
+    }
+  }
+}

workshop/src/main/java/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment1Rules.java

@@ -0,0 +1,11 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+/** Refaster rules for the first assignment of the workshop. */
+final class WorkshopAssignment1Rules {
+  private WorkshopAssignment1Rules() {}
+
+  /** Prefer {@link String#String(char[])} over {@link String#copyValueOf(char[])}. */
+  static final class NewStringCharArray {
+    // XXX: Implement this Refaster rule.
+  }
+}

workshop/src/main/java/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment2Rules.java

@@ -0,0 +1,34 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import com.google.common.collect.ImmutableList;
+import com.google.errorprone.refaster.Refaster;
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+
+import java.util.Collections;
+import java.util.List;
+
+/** Refaster rules for the second assignment of the workshop. */
+final class WorkshopAssignment2Rules {
+  private WorkshopAssignment2Rules() {}
+
+  /**
+   * Prefer {@link ImmutableList#of(Object)} over alternatives that don't communicate the
+   * immutability of the resulting list at the type level.
+   */
+  static final class ImmutableListOfOne<T> {
+    @BeforeTemplate
+    static <T> List<T> before(T t) {
+      return ImmutableList.copyOf(
+          Refaster.anyOf(
+              Collections.singletonList(t),
+              List.of(t))
+      );
+    }
+
+    @AfterTemplate
+    static <T> List<T> after(T t) {
+      return ImmutableList.of(t);
+    }
+  }
+}

workshop/src/main/java/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment3Rules.java

@@ -0,0 +1,21 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import com.google.common.base.Preconditions;
+
+/** Refaster rules for the third assignment of the workshop. */
+@SuppressWarnings("UnusedTypeParameter" /* Ignore this for demo purposes. */)
+final class WorkshopAssignment3Rules {
+  private WorkshopAssignment3Rules() {}
+
+  // XXX: Tip: check the input and output files to see the *expected* refactoring.
+
+  /** Prefer {@link Preconditions#checkArgument(boolean)} over if statements. */
+  static final class CheckArgumentWithoutMessage {
+    // XXX: Implement the Refaster rule to get the test green.
+  }
+
+  /** Prefer {@link Preconditions#checkArgument(boolean, Object)} over if statements. */
+  static final class CheckArgumentWithMessage {
+    // XXX: Implement the Refaster rule to get the test green.
+  }
+}

workshop/src/main/java/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment4Rules.java

@@ -0,0 +1,25 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+/** Refaster rules for the fourth assignment of the workshop. */
+@SuppressWarnings("java:S1698" /* Reference comparison is valid for enums. */)
+final class WorkshopAssignment4Rules {
+  private WorkshopAssignment4Rules() {}
+
+  // The test fails because non Enum comparisons are also rewritten.
+  // Fix the test by tweaking the type parameters.
+
+  // XXX: Get the test to pass by improving the Refaster rule (uncommented it first).
+
+  //  static final class PrimitiveOrReferenceEqualityEnum<T> {
+  //    @BeforeTemplate
+  //    boolean before(T a, T b) {
+  //      return Refaster.anyOf(a.equals(b), Objects.equals(a, b));
+  //    }
+  //
+  //    @AfterTemplate
+  //    @AlsoNegation
+  //    boolean after(T a, T b) {
+  //      return a == b;
+  //    }
+  //  }
+}

workshop/src/main/java/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment5Rules.java

@@ -0,0 +1,12 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+/** Refaster rules for the fifth assignment of the workshop. */
+@SuppressWarnings("UnusedTypeParameter" /* Ignore this for demo purposes. */)
+final class WorkshopAssignment5Rules {
+  private WorkshopAssignment5Rules() {}
+
+  abstract static class StreamDoAllMatch<T> {
+    // XXX: Implement the Refaster rule to get the test green.
+    // Tip: use the `@Placeholder` annotation.
+  }
+}

workshop/src/test/java/tech/picnic/errorprone/workshop/bugpatterns/Assignment0Assignment0DeleteEmptyMethodTest.java

@@ -0,0 +1,70 @@
+package tech.picnic.errorprone.workshop.bugpatterns;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+@Disabled("Enable this when implementing the BugChecker.")
+final class Assignment0Assignment0DeleteEmptyMethodTest {
+  @Test
+  void identification() {
+    CompilationTestHelper.newInstance(Assignment0DeleteEmptyMethod.class, getClass())
+        .addSourceLines(
+            "A.java",
+            "class A {",
+            "  Object m1() {",
+            "    return null;",
+            "  }",
+            "",
+            "  void m2() {",
+            "    System.out.println(42);",
+            "  }",
+            "",
+            "  // BUG: Diagnostic contains:",
+            "  static void m3() {}",
+            "",
+            "  interface F {",
+            "    void fun();",
+            "  }",
+            "}")
+        .addSourceLines(
+            "B.java",
+            "final class B implements A.F {",
+            "  @Override",
+            "  public void fun() {}",
+            "",
+            "  /** Javadoc. */",
+            "  // BUG: Diagnostic contains:",
+            "  void m4() {}",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    BugCheckerRefactoringTestHelper.newInstance(Assignment0DeleteEmptyMethod.class, getClass())
+        .addInputLines(
+            "A.java",
+            "final class A {",
+            "",
+            "  void instanceMethod() {}",
+            "",
+            "  static void staticMethod() {}",
+            "",
+            "  static void staticMethodWithComment() {",
+            "    System.out.println(42);",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "final class A {",
+            "",
+            "  static void staticMethodWithComment() {",
+            "    System.out.println(42);",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

workshop/src/test/java/tech/picnic/errorprone/workshop/bugpatterns/Assignment1AssertJIsNullMethodTest.java

@@ -0,0 +1,60 @@
+package tech.picnic.errorprone.workshop.bugpatterns;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+@Disabled("Enable this when implementing the BugChecker.")
+final class Assignment1AssertJIsNullMethodTest {
+  @Test
+  void identification() {
+    CompilationTestHelper.newInstance(Assignment1AssertJIsNullMethod.class, getClass())
+        .addSourceLines(
+            "A.java",
+            "import static org.assertj.core.api.Assertions.assertThat;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    assertThat(1).isEqualTo(1);",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(1).isEqualTo(null);",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(\"foo\").isEqualTo(null);",
+            "    isEqualTo(null);",
+            "  }",
+            "",
+            "  private boolean isEqualTo(Object value) {",
+            "    return value.equals(\"bar\");",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    BugCheckerRefactoringTestHelper.newInstance(Assignment1AssertJIsNullMethod.class, getClass())
+        .addInputLines(
+            "A.java",
+            "import static org.assertj.core.api.Assertions.assertThat;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    assertThat(1).isEqualTo(null);",
+            "    assertThat(\"foo\").isEqualTo(null);",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import static org.assertj.core.api.Assertions.assertThat;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    assertThat(1).isNull();",
+            "    assertThat(\"foo\").isNull();",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

workshop/src/test/java/tech/picnic/errorprone/workshop/bugpatterns/Assignment2DropMockitoEqTest.java

@@ -0,0 +1,102 @@
+package tech.picnic.errorprone.workshop.bugpatterns;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+@Disabled("Enable this when implementing the BugChecker.")
+final class Assignment2DropMockitoEqTest {
+  @Test
+  void identification() {
+    CompilationTestHelper.newInstance(Assignment2DropMockitoEq.class, getClass())
+        .addSourceLines(
+            "A.java",
+            "import static org.mockito.ArgumentMatchers.eq;",
+            "import static org.mockito.ArgumentMatchers.notNull;",
+            "import static org.mockito.Mockito.doAnswer;",
+            "import static org.mockito.Mockito.mock;",
+            "",
+            "import java.util.function.BiConsumer;",
+            "import java.util.function.Consumer;",
+            "import org.mockito.ArgumentMatchers;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Runnable runnable = mock(Runnable.class);",
+            "    doAnswer(inv -> null).when(runnable).run();",
+            "",
+            "    Consumer<String> consumer = mock(Consumer.class);",
+            "    doAnswer(inv -> null).when(consumer).accept(\"foo\");",
+            "    doAnswer(inv -> null).when(consumer).accept(notNull());",
+            "    // BUG: Diagnostic contains:",
+            "    doAnswer(inv -> null).when(consumer).accept(ArgumentMatchers.eq(\"foo\"));",
+            "    // BUG: Diagnostic contains:",
+            "    doAnswer(inv -> null).when(consumer).accept(eq(toString()));",
+            "",
+            "    BiConsumer<Integer, String> biConsumer = mock(BiConsumer.class);",
+            "    doAnswer(inv -> null).when(biConsumer).accept(0, \"foo\");",
+            "    doAnswer(inv -> null).when(biConsumer).accept(eq(0), notNull());",
+            "    doAnswer(inv -> null).when(biConsumer).accept(notNull(), eq(\"foo\"));",
+            "    doAnswer(inv -> null)",
+            "        .when(biConsumer)",
+            "        // BUG: Diagnostic contains:",
+            "        .accept(ArgumentMatchers.eq(0), ArgumentMatchers.eq(\"foo\"));",
+            "    // BUG: Diagnostic contains:",
+            "    doAnswer(inv -> null).when(biConsumer).accept(eq(hashCode()), eq(toString()));",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    BugCheckerRefactoringTestHelper.newInstance(Assignment2DropMockitoEq.class, getClass())
+        .addInputLines(
+            "A.java",
+            "import static org.mockito.ArgumentMatchers.eq;",
+            "import static org.mockito.Mockito.doAnswer;",
+            "import static org.mockito.Mockito.mock;",
+            "",
+            "import java.util.function.BiConsumer;",
+            "import java.util.function.Consumer;",
+            "import org.mockito.ArgumentMatchers;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Consumer<String> consumer = mock(Consumer.class);",
+            "    doAnswer(inv -> null).when(consumer).accept(ArgumentMatchers.eq(\"foo\"));",
+            "    doAnswer(inv -> null).when(consumer).accept(eq(toString()));",
+            "",
+            "    BiConsumer<Integer, String> biConsumer = mock(BiConsumer.class);",
+            "    doAnswer(inv -> null)",
+            "        .when(biConsumer)",
+            "        .accept(ArgumentMatchers.eq(0), ArgumentMatchers.eq(\"foo\"));",
+            "    doAnswer(inv -> null).when(biConsumer).accept(eq(hashCode()), eq(toString()));",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import static org.mockito.ArgumentMatchers.eq;",
+            "import static org.mockito.Mockito.doAnswer;",
+            "import static org.mockito.Mockito.mock;",
+            "",
+            "import java.util.function.BiConsumer;",
+            "import java.util.function.Consumer;",
+            "import org.mockito.ArgumentMatchers;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Consumer<String> consumer = mock(Consumer.class);",
+            "    doAnswer(inv -> null).when(consumer).accept(\"foo\");",
+            "    doAnswer(inv -> null).when(consumer).accept(toString());",
+            "",
+            "    BiConsumer<Integer, String> biConsumer = mock(BiConsumer.class);",
+            "    doAnswer(inv -> null).when(biConsumer).accept(0, \"foo\");",
+            "    doAnswer(inv -> null).when(biConsumer).accept(hashCode(), toString());",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

workshop/src/test/java/tech/picnic/errorprone/workshop/bugpatterns/Assignment3DropAutowiredConstructorAnnotationTest.java

@@ -0,0 +1,106 @@
+package tech.picnic.errorprone.workshop.bugpatterns;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+@Disabled("Enable this when implementing the BugChecker.")
+final class Assignment3DropAutowiredConstructorAnnotationTest {
+  @Test
+  void identification() {
+    CompilationTestHelper.newInstance(
+            Assignment3DropAutowiredConstructorAnnotation.class, getClass())
+        .addSourceLines(
+            "Container.java",
+            "import com.google.errorprone.annotations.Immutable;",
+            "import java.util.List;",
+            "import org.springframework.beans.factory.annotation.Autowired;",
+            "",
+            "interface Container {",
+            "  @Immutable",
+            "  class A {",
+            "    A() {}",
+            "  }",
+            "",
+            "  class B {",
+            "    @Autowired",
+            "    void setProperty(Object o) {}",
+            "  }",
+            "",
+            "  class C {",
+            "    // BUG: Diagnostic contains:",
+            "    @Autowired",
+            "    C() {}",
+            "  }",
+            "",
+            "  class D {",
+            "    // BUG: Diagnostic contains:",
+            "    @Autowired",
+            "    D(String x) {}",
+            "  }",
+            "",
+            "  class E {",
+            "    @Autowired",
+            "    E() {}",
+            "",
+            "    E(String x) {}",
+            "  }",
+            "",
+            "  class F {",
+            "    F() {}",
+            "",
+            "    @Autowired",
+            "    F(String x) {}",
+            "  }",
+            "",
+            "  class G {",
+            "    @Autowired private Object o;",
+            "  }",
+            "",
+            "  class H {",
+            "    @SafeVarargs",
+            "    H(List<String>... lists) {}",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    BugCheckerRefactoringTestHelper.newInstance(
+            Assignment3DropAutowiredConstructorAnnotation.class, getClass())
+        .addInputLines(
+            "Container.java",
+            "import org.springframework.beans.factory.annotation.Autowired;",
+            "",
+            "interface Container {",
+            "  class A {",
+            "    @Autowired",
+            "    @Deprecated",
+            "    A() {}",
+            "  }",
+            "",
+            "  class B {",
+            "    @Autowired",
+            "    B(String x) {}",
+            "  }",
+            "}")
+        .addOutputLines(
+            "Container.java",
+            "import org.springframework.beans.factory.annotation.Autowired;",
+            "",
+            "interface Container {",
+            "  class A {",
+            "    @Deprecated",
+            "    A() {}",
+            "  }",
+            "",
+            "  class B {",
+            "    B(String x) {}",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

workshop/src/test/java/tech/picnic/errorprone/workshop/bugpatterns/Assignment4JUnitTestMethodDeclarationTest.java

@@ -0,0 +1,91 @@
+package tech.picnic.errorprone.workshop.bugpatterns;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+@Disabled("Enable this to validate part 1.")
+final class Assignment4JUnitTestMethodDeclarationTest {
+  @Test
+  void identificationIllegalModifiers() {
+    CompilationTestHelper.newInstance(Assignment4JUnitTestMethodDeclaration.class, getClass())
+        .addSourceLines(
+            "A.java",
+            "import org.junit.jupiter.api.Test;",
+            "",
+            "class A {",
+            "  @Test",
+            "  void method1() {}",
+            "",
+            "  @Test",
+            "  // BUG: Diagnostic contains:",
+            "  public void method2() {}",
+            "",
+            "  @Test",
+            "  // BUG: Diagnostic contains:",
+            "  protected void method3() {}",
+            "",
+            "  @Test",
+            "  // BUG: Diagnostic contains:",
+            "  private void method4() {}",
+            "",
+            "  public void method5() {}",
+            "",
+            "  protected void method6() {}",
+            "",
+            "  private void method7() {}",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacementIllegalModifiers() {
+    BugCheckerRefactoringTestHelper.newInstance(
+            Assignment4JUnitTestMethodDeclaration.class, getClass())
+        .addInputLines(
+            "A.java",
+            "import org.junit.jupiter.api.Test;",
+            "",
+            "class A {",
+            "  @Test",
+            "  void foo() {}",
+            "",
+            "  @Test",
+            "  public void bar() {}",
+            "",
+            "  @Test",
+            "  protected void baz() {}",
+            "",
+            "  @Test",
+            "  private void qux() {}",
+            "",
+            "  public void quux() {}",
+            "",
+            "  private void quuz() {}",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import org.junit.jupiter.api.Test;",
+            "",
+            "class A {",
+            "  @Test",
+            "  void foo() {}",
+            "",
+            "  @Test",
+            "  void bar() {}",
+            "",
+            "  @Test",
+            "  void baz() {}",
+            "",
+            "  @Test",
+            "  void qux() {}",
+            "",
+            "  public void quux() {}",
+            "",
+            "  private void quuz() {}",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

workshop/src/test/java/tech/picnic/errorprone/workshop/bugpatterns/Assignment5DeleteIdentityConversionTest.java

@@ -0,0 +1,223 @@
+package tech.picnic.errorprone.workshop.bugpatterns;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+@Disabled("Enable this when implementing the BugChecker.")
+final class Assignment5DeleteIdentityConversionTest {
+  @Test
+  void identification() {
+    CompilationTestHelper.newInstance(Assignment5DeleteIdentityConversion.class, getClass())
+        .addSourceLines(
+            "A.java",
+            "import static com.google.errorprone.matchers.Matchers.instanceMethod;",
+            "import static com.google.errorprone.matchers.Matchers.staticMethod;",
+            "",
+            "import com.google.common.collect.ImmutableBiMap;",
+            "import com.google.common.collect.ImmutableList;",
+            "import com.google.common.collect.ImmutableListMultimap;",
+            "import com.google.common.collect.ImmutableMap;",
+            "import com.google.common.collect.ImmutableMultimap;",
+            "import com.google.common.collect.ImmutableMultiset;",
+            "import com.google.common.collect.ImmutableRangeMap;",
+            "import com.google.common.collect.ImmutableRangeSet;",
+            "import com.google.common.collect.ImmutableSet;",
+            "import com.google.common.collect.ImmutableSetMultimap;",
+            "import com.google.common.collect.ImmutableTable;",
+            "import com.google.errorprone.matchers.Matcher;",
+            "import com.google.errorprone.matchers.Matchers;",
+            "",
+            "public final class A {",
+            "  public void m() {",
+            "    // BUG: Diagnostic contains:",
+            "    Matcher allOf1 = Matchers.allOf(instanceMethod());",
+            "    Matcher allOf2 = Matchers.allOf(instanceMethod(), staticMethod());",
+            "    // BUG: Diagnostic contains:",
+            "    Matcher anyOf1 = Matchers.anyOf(staticMethod());",
+            "    Matcher anyOf2 = Matchers.anyOf(instanceMethod(), staticMethod());",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Boolean b1 = Boolean.valueOf(Boolean.FALSE);",
+            "    // BUG: Diagnostic contains:",
+            "    Boolean b2 = Boolean.valueOf(false);",
+            "    // BUG: Diagnostic contains:",
+            "    boolean b3 = Boolean.valueOf(Boolean.FALSE);",
+            "    // BUG: Diagnostic contains:",
+            "    boolean b4 = Boolean.valueOf(false);",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Byte byte1 = Byte.valueOf((Byte) Byte.MIN_VALUE);",
+            "    // BUG: Diagnostic contains:",
+            "    Byte byte2 = Byte.valueOf(Byte.MIN_VALUE);",
+            "    // BUG: Diagnostic contains:",
+            "    byte byte3 = Byte.valueOf((Byte) Byte.MIN_VALUE);",
+            "    // BUG: Diagnostic contains:",
+            "    byte byte4 = Byte.valueOf(Byte.MIN_VALUE);",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Character c1 = Character.valueOf((Character) 'a');",
+            "    // BUG: Diagnostic contains:",
+            "    Character c2 = Character.valueOf('a');",
+            "    // BUG: Diagnostic contains:",
+            "    char c3 = Character.valueOf((Character) 'a');",
+            "    // BUG: Diagnostic contains:",
+            "    char c4 = Character.valueOf('a');",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Double d1 = Double.valueOf((Double) 0.0);",
+            "    // BUG: Diagnostic contains:",
+            "    Double d2 = Double.valueOf(0.0);",
+            "    // BUG: Diagnostic contains:",
+            "    double d3 = Double.valueOf((Double) 0.0);",
+            "    // BUG: Diagnostic contains:",
+            "    double d4 = Double.valueOf(0.0);",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Float f1 = Float.valueOf((Float) 0.0F);",
+            "    // BUG: Diagnostic contains:",
+            "    Float f2 = Float.valueOf(0.0F);",
+            "    // BUG: Diagnostic contains:",
+            "    float f3 = Float.valueOf((Float) 0.0F);",
+            "    // BUG: Diagnostic contains:",
+            "    float f4 = Float.valueOf(0.0F);",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Integer i1 = Integer.valueOf((Integer) 1);",
+            "    // BUG: Diagnostic contains:",
+            "    Integer i2 = Integer.valueOf(1);",
+            "    // BUG: Diagnostic contains:",
+            "    int i3 = Integer.valueOf((Integer) 1);",
+            "    // BUG: Diagnostic contains:",
+            "    int i4 = Integer.valueOf(1);",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Long l1 = Long.valueOf((Long) 1L);",
+            "    // BUG: Diagnostic contains:",
+            "    Long l2 = Long.valueOf(1L);",
+            "    // BUG: Diagnostic contains:",
+            "    long l3 = Long.valueOf((Long) 1L);",
+            "    // BUG: Diagnostic contains:",
+            "    long l4 = Long.valueOf(1L);",
+            "",
+            "    Long l5 = Long.valueOf((Integer) 1);",
+            "    Long l6 = Long.valueOf(1);",
+            "    // BUG: Diagnostic contains:",
+            "    long l7 = Long.valueOf((Integer) 1);",
+            "    // BUG: Diagnostic contains:",
+            "    long l8 = Long.valueOf(1);",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Short s1 = Short.valueOf((Short) Short.MIN_VALUE);",
+            "    // BUG: Diagnostic contains:",
+            "    Short s2 = Short.valueOf(Short.MIN_VALUE);",
+            "    // BUG: Diagnostic contains:",
+            "    short s3 = Short.valueOf((Short) Short.MIN_VALUE);",
+            "    // BUG: Diagnostic contains:",
+            "    short s4 = Short.valueOf(Short.MIN_VALUE);",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    String boolStr = Boolean.valueOf(Boolean.FALSE).toString();",
+            "    int boolHash = Boolean.valueOf(false).hashCode();",
+            "    // BUG: Diagnostic contains:",
+            "    int byteHash = Byte.valueOf((Byte) Byte.MIN_VALUE).hashCode();",
+            "    String byteStr = Byte.valueOf(Byte.MIN_VALUE).toString();",
+            "",
+            "    String str1 = String.valueOf(0);",
+            "    // BUG: Diagnostic contains:",
+            "    String str2 = String.valueOf(\"1\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    ImmutableBiMap<Object, Object> o1 = ImmutableBiMap.copyOf(ImmutableBiMap.of());",
+            "    // BUG: Diagnostic contains:",
+            "    ImmutableList<Object> o2 = ImmutableList.copyOf(ImmutableList.of());",
+            "    ImmutableListMultimap<Object, Object> o3 =",
+            "        // BUG: Diagnostic contains:",
+            "        ImmutableListMultimap.copyOf(ImmutableListMultimap.of());",
+            "    // BUG: Diagnostic contains:",
+            "    ImmutableMap<Object, Object> o4 = ImmutableMap.copyOf(ImmutableMap.of());",
+            "    // BUG: Diagnostic contains:",
+            "    ImmutableMultimap<Object, Object> o5 = ImmutableMultimap.copyOf(ImmutableMultimap.of());",
+            "    // BUG: Diagnostic contains:",
+            "    ImmutableMultiset<Object> o6 = ImmutableMultiset.copyOf(ImmutableMultiset.of());",
+            "    // BUG: Diagnostic contains:",
+            "    ImmutableRangeMap<String, Object> o7 = ImmutableRangeMap.copyOf(ImmutableRangeMap.of());",
+            "    // BUG: Diagnostic contains:",
+            "    ImmutableRangeSet<String> o8 = ImmutableRangeSet.copyOf(ImmutableRangeSet.of());",
+            "    // BUG: Diagnostic contains:",
+            "    ImmutableSet<Object> o9 = ImmutableSet.copyOf(ImmutableSet.of());",
+            "    ImmutableSetMultimap<Object, Object> o10 =",
+            "        // BUG: Diagnostic contains:",
+            "        ImmutableSetMultimap.copyOf(ImmutableSetMultimap.of());",
+            "    // BUG: Diagnostic contains:",
+            "    ImmutableTable<Object, Object, Object> o11 = ImmutableTable.copyOf(ImmutableTable.of());",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    BugCheckerRefactoringTestHelper.newInstance(
+            Assignment5DeleteIdentityConversion.class, getClass())
+        .addInputLines(
+            "A.java",
+            "import static com.google.errorprone.matchers.Matchers.staticMethod;",
+            "import static org.mockito.Mockito.when;",
+            "",
+            "import com.google.common.collect.ImmutableCollection;",
+            "import com.google.common.collect.ImmutableList;",
+            "import com.google.common.collect.ImmutableSet;",
+            "import java.util.ArrayList;",
+            "import java.util.Collection;",
+            "",
+            "public final class A {",
+            "  public void m() {",
+            "    ImmutableSet<Object> set1 = ImmutableSet.copyOf(ImmutableSet.of());",
+            "    ImmutableSet<Object> set2 = ImmutableSet.copyOf(ImmutableList.of());",
+            "",
+            "    ImmutableCollection<Integer> list1 = ImmutableList.copyOf(ImmutableList.of(1));",
+            "    ImmutableCollection<Integer> list2 = ImmutableList.copyOf(new ArrayList<>(ImmutableList.of(1)));",
+            "",
+            "    Collection<Integer> c1 = ImmutableSet.copyOf(ImmutableSet.of(1));",
+            "    Collection<Integer> c2 = ImmutableList.copyOf(new ArrayList<>(ImmutableList.of(1)));",
+            "",
+            "    Object o1 = ImmutableSet.copyOf(ImmutableList.of());",
+            "    Object o2 = ImmutableSet.copyOf(ImmutableSet.of());",
+            "",
+            "    when(\"foo\".contains(\"f\")).thenAnswer(inv -> ImmutableSet.copyOf(ImmutableList.of(1)));",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import static com.google.errorprone.matchers.Matchers.staticMethod;",
+            "import static org.mockito.Mockito.when;",
+            "",
+            "import com.google.common.collect.ImmutableCollection;",
+            "import com.google.common.collect.ImmutableList;",
+            "import com.google.common.collect.ImmutableSet;",
+            "import java.util.ArrayList;",
+            "import java.util.Collection;",
+            "",
+            "public final class A {",
+            "  public void m() {",
+            "    ImmutableSet<Object> set1 = ImmutableSet.of();",
+            "    ImmutableSet<Object> set2 = ImmutableSet.copyOf(ImmutableList.of());",
+            "",
+            "    ImmutableCollection<Integer> list1 = ImmutableList.of(1);",
+            "    ImmutableCollection<Integer> list2 = ImmutableList.copyOf(new ArrayList<>(ImmutableList.of(1)));",
+            "",
+            "    Collection<Integer> c1 = ImmutableSet.of(1);",
+            "    Collection<Integer> c2 = ImmutableList.copyOf(new ArrayList<>(ImmutableList.of(1)));",
+            "",
+            "    Object o1 = ImmutableSet.copyOf(ImmutableList.of());",
+            "    Object o2 = ImmutableSet.of();",
+            "",
+            "    when(\"foo\".contains(\"f\")).thenAnswer(inv -> ImmutableSet.copyOf(ImmutableList.of(1)));",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

workshop/src/test/java/tech/picnic/errorprone/workshop/refasterrules/WorkshopRefasterRulesTest.java

@@ -0,0 +1,37 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollection;
+
+final class WorkshopRefasterRulesTest {
+  @Test
+  void validateExampleRuleCollection() {
+    RefasterRuleCollection.validate(WorkshopAssignment0Rules.class);
+  }
+
+  @Test
+  void validateFirstWorkshopAssignment() {
+    RefasterRuleCollection.validate(WorkshopAssignment1Rules.class);
+  }
+
+  @Test
+  void validateSecondWorkshopAssignment() {
+    RefasterRuleCollection.validate(WorkshopAssignment2Rules.class);
+  }
+
+  @Test
+  void validateThirdWorkshopAssignment() {
+    RefasterRuleCollection.validate(WorkshopAssignment3Rules.class);
+  }
+
+  @Test
+  void validateFourthWorkshopAssignment() {
+    RefasterRuleCollection.validate(WorkshopAssignment4Rules.class);
+  }
+
+  @Test
+  void validateFifthWorkshopAssignment() {
+    RefasterRuleCollection.validate(WorkshopAssignment5Rules.class);
+  }
+}

workshop/src/test/resources/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment0RulesTestInput.java

@@ -0,0 +1,10 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class WorkshopAssignment0RulesTest implements RefasterRuleCollectionTestCase {
+  boolean testExampleStringIsEmpty() {
+    boolean b = "foo".length() == 0;
+    return "bar".length() == 0;
+  }
+}

workshop/src/test/resources/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment0RulesTestOutput.java

@@ -0,0 +1,10 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class WorkshopAssignment0RulesTest implements RefasterRuleCollectionTestCase {
+  boolean testExampleStringIsEmpty() {
+    boolean b = "foo".isEmpty();
+    return "bar".isEmpty();
+  }
+}

workshop/src/test/resources/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment1RulesTestInput.java

@@ -0,0 +1,11 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class WorkshopAssignment1RulesTest implements RefasterRuleCollectionTestCase {
+  String testNewStringCharArray() {
+    String.copyValueOf(new char[] {});
+    String.copyValueOf(new char[] {'f', 'o', 'o'});
+    return String.copyValueOf(new char[] {'b', 'a', 'r'});
+  }
+}

workshop/src/test/resources/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment1RulesTestOutput.java

@@ -0,0 +1,11 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class WorkshopAssignment1RulesTest implements RefasterRuleCollectionTestCase {
+  String testNewStringCharArray() {
+    new String(new char[] {});
+    new String(new char[] {'f', 'o', 'o'});
+    return new String(new char[] {'b', 'a', 'r'});
+  }
+}

workshop/src/test/resources/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment2RulesTestInput.java

@@ -0,0 +1,20 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import com.google.common.collect.ImmutableSet;
+import java.util.Collections;
+import java.util.List;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class WorkshopAssignment2RulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<Object> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(Collections.class);
+  }
+
+  List<Object> testImmutableListOfOne() {
+    Collections.singletonList(1);
+    Collections.singletonList("foo");
+    List.of(1);
+    return List.of("bar");
+  }
+}

workshop/src/test/resources/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment2RulesTestOutput.java

@@ -0,0 +1,21 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import java.util.Collections;
+import java.util.List;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class WorkshopAssignment2RulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<Object> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(Collections.class);
+  }
+
+  List<Object> testImmutableListOfOne() {
+    ImmutableList.of(1);
+    ImmutableList.of("foo");
+    ImmutableList.of(1);
+    return ImmutableList.of("bar");
+  }
+}

workshop/src/test/resources/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment3RulesTestInput.java

@@ -0,0 +1,24 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class WorkshopAssignment3RulesTest implements RefasterRuleCollectionTestCase {
+  void testCheckArgumentWithoutMessage() {
+    if (!"foo".isEmpty()) {
+      throw new IllegalArgumentException();
+    }
+    if (!"bar".isEmpty()) {
+      throw new IllegalArgumentException();
+    }
+  }
+
+  void testCheckArgumentWithMessage() {
+    if (!"foo".isEmpty()) {
+      throw new IllegalArgumentException("The string is not empty");
+    }
+    if (!"bar".isEmpty()) {
+      throw new IllegalArgumentException(
+          "The rule should be able rewrite all kinds of messages ;).");
+    }
+  }
+}

workshop/src/test/resources/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment3RulesTestOutput.java

@@ -0,0 +1,17 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class WorkshopAssignment3RulesTest implements RefasterRuleCollectionTestCase {
+  void testCheckArgumentWithoutMessage() {
+    checkArgument("foo".isEmpty());
+    checkArgument("bar".isEmpty());
+  }
+
+  void testCheckArgumentWithMessage() {
+    checkArgument("foo".isEmpty(), "The string is not empty");
+    checkArgument("bar".isEmpty(), "The rule should be able rewrite all kinds of messages ;).");
+  }
+}

workshop/src/test/resources/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment4RulesTestInput.java

@@ -0,0 +1,25 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import com.google.common.collect.ImmutableSet;
+import java.math.RoundingMode;
+import java.util.Objects;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class WorkshopAssignment4RulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<Object> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(Objects.class);
+  }
+
+  ImmutableSet<Boolean> testPrimitiveOrReferenceEqualityEnum() {
+    // Don't pay attention to the `ImmutableSet#of` here, it's just syntactical sugar for the
+    // testing framework.
+    return ImmutableSet.of(
+        "foo".equals("bar"),
+        Integer.valueOf(1).equals(2),
+        RoundingMode.UP.equals(RoundingMode.DOWN),
+        Objects.equals(RoundingMode.UP, RoundingMode.DOWN),
+        !RoundingMode.UP.equals(RoundingMode.DOWN),
+        !Objects.equals(RoundingMode.UP, RoundingMode.DOWN));
+  }
+}

workshop/src/test/resources/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment4RulesTestOutput.java

@@ -0,0 +1,25 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import com.google.common.collect.ImmutableSet;
+import java.math.RoundingMode;
+import java.util.Objects;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class WorkshopAssignment4RulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<Object> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(Objects.class);
+  }
+
+  ImmutableSet<Boolean> testPrimitiveOrReferenceEqualityEnum() {
+    // Don't pay attention to the `ImmutableSet#of` here, it's just syntactical sugar for the
+    // testing framework.
+    return ImmutableSet.of(
+        "foo".equals("bar"),
+        Integer.valueOf(1).equals(2),
+        RoundingMode.UP == RoundingMode.DOWN,
+        RoundingMode.UP == RoundingMode.DOWN,
+        RoundingMode.UP != RoundingMode.DOWN,
+        RoundingMode.UP != RoundingMode.DOWN);
+  }
+}

workshop/src/test/resources/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment5RulesTestInput.java

@@ -0,0 +1,11 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import java.util.stream.Stream;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class WorkshopAssignment5RulesTest implements RefasterRuleCollectionTestCase {
+  boolean testStreamDoAllMatch() {
+    boolean example = Stream.of("foo").noneMatch(s -> !s.isBlank());
+    return Stream.of("bar").noneMatch(b -> !b.startsWith("b"));
+  }
+}

workshop/src/test/resources/tech/picnic/errorprone/workshop/refasterrules/WorkshopAssignment5RulesTestOutput.java

@@ -0,0 +1,11 @@
+package tech.picnic.errorprone.workshop.refasterrules;
+
+import java.util.stream.Stream;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class WorkshopAssignment5RulesTest implements RefasterRuleCollectionTestCase {
+  boolean testStreamDoAllMatch() {
+    boolean example = Stream.of("foo").allMatch(s -> s.isBlank());
+    return Stream.of("bar").allMatch(b -> b.startsWith("b"));
+  }
+}