Improve tests for WebClient

See:
- https://assertj.github.io/doc/#assertj-core-release-notes
- https://github.com/joel-costigliola/assertj-core/compare/assertj-core-3.20.2...assertj-core-3.21.0

error-prone-contrib/pom.xml

@@ -171,6 +171,11 @@
             <artifactId>spring-context</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-core</artifactId>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-test</artifactId>

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJTemplates.java

@@ -39,6 +39,7 @@ import java.util.stream.Collector;
 import java.util.stream.Stream;
 import org.assertj.core.api.AbstractAssert;
 import org.assertj.core.api.AbstractBooleanAssert;
+import org.assertj.core.api.AbstractCollectionAssert;
 import org.assertj.core.api.AbstractComparableAssert;
 import org.assertj.core.api.AbstractDoubleAssert;
 import org.assertj.core.api.AbstractIntegerAssert;
@@ -529,7 +530,7 @@ final class AssertJTemplates {
 
   static final class AssertThatSetsAreEqual<S, T extends S> {
     @BeforeTemplate
-    IterableAssert<S> before(Set<S> set1, Set<T> set2) {
+    AbstractCollectionAssert<?, ?, S, ?> before(Set<S> set1, Set<T> set2) {
       return Refaster.anyOf(
           assertThat(set1).isEqualTo(set2),
           assertThat(set1).containsExactlyInAnyOrderElementsOf(set2));
@@ -537,7 +538,7 @@ final class AssertJTemplates {
 
     @AfterTemplate
     @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
-    IterableAssert<S> after(Set<S> set1, Set<T> set2) {
+    AbstractCollectionAssert<?, ?, S, ?> after(Set<S> set1, Set<T> set2) {
       return assertThat(set1).hasSameElementsAs(set2);
     }
   }
@@ -548,13 +549,13 @@ final class AssertJTemplates {
 
   static final class AssertThatMultisetsAreEqual<S, T extends S> {
     @BeforeTemplate
-    IterableAssert<S> before(Multiset<S> multiset1, Multiset<T> multiset2) {
+    AbstractCollectionAssert<?, ?, S, ?> before(Multiset<S> multiset1, Multiset<T> multiset2) {
       return assertThat(multiset1).isEqualTo(multiset2);
     }
 
     @AfterTemplate
     @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
-    IterableAssert<S> after(Multiset<S> multiset1, Multiset<T> multiset2) {
+    AbstractCollectionAssert<?, ?, S, ?> after(Multiset<S> multiset1, Multiset<T> multiset2) {
       return assertThat(multiset1).containsExactlyInAnyOrderElementsOf(multiset2);
     }
   }
@@ -934,7 +935,7 @@ final class AssertJTemplates {
     }
 
     @BeforeTemplate
-    IterableAssert<T> before2(
+    AbstractCollectionAssert<?, ?, T, ?> before2(
         Stream<S> stream, Collector<S, ?, ? extends Multiset<T>> collector, Iterable<U> iterable) {
       return assertThat(stream.collect(collector)).containsExactlyInAnyOrderElementsOf(iterable);
     }
@@ -955,7 +956,7 @@ final class AssertJTemplates {
     }
 
     @BeforeTemplate
-    IterableAssert<T> before2(
+    AbstractCollectionAssert<?, ?, T, ?> before2(
         Stream<S> stream, Collector<S, ?, ? extends Multiset<T>> collector, U[] array) {
       return assertThat(stream.collect(collector)).containsExactlyInAnyOrder(array);
     }
@@ -979,7 +980,7 @@ final class AssertJTemplates {
 
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamContainsExactlyInAnyOrder" /* Varargs converted to array. */)
-    IterableAssert<T> before2(
+    AbstractCollectionAssert<?, ?, T, ?> before2(
         Stream<S> stream, Collector<S, ?, ? extends Multiset<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector))
           .containsExactlyInAnyOrder(Refaster.asVarargs(elements));

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ImmutableListTemplates.java

@@ -128,19 +128,6 @@ final class ImmutableListTemplates {
     }
   }
 
-  /** Don't call {@link ImmutableList#asList()}; it is a no-op. */
-  static final class ImmutableListAsList<T> {
-    @BeforeTemplate
-    ImmutableList<T> before(ImmutableList<T> list) {
-      return list.asList();
-    }
-
-    @AfterTemplate
-    ImmutableList<T> after(ImmutableList<T> list) {
-      return list;
-    }
-  }
-
   /** Prefer {@link ImmutableList#sortedCopyOf(Iterable)} over more contrived alternatives. */
   static final class ImmutableListSortedCopyOf<T extends Comparable<? super T>> {
     @BeforeTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/OptionalTemplates.java

@@ -91,19 +91,6 @@ final class OptionalTemplates {
     }
   }
 
-  /** Prefer {@link Optional#stream()} over the Guava alternative. */
-  static final class OptionalToStream<T> {
-    @BeforeTemplate
-    Stream<T> before(Optional<T> optional) {
-      return Streams.stream(optional);
-    }
-
-    @AfterTemplate
-    Stream<T> after(Optional<T> optional) {
-      return optional.stream();
-    }
-  }
-
   /**
    * Don't use the ternary operator to extract the first element of a possibly-empty {@link
    * Iterator} as an {@link Optional}.

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/WebClientTemplates.java

@@ -1,12 +1,19 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static java.util.function.Function.identity;
 import static org.springframework.web.reactive.function.BodyInserters.fromValue;
 
+import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import java.util.Collection;
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.test.web.reactive.server.WebTestClient;
+import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.reactive.function.client.WebClient.RequestBodySpec;
 import org.springframework.web.reactive.function.client.WebClient.RequestHeadersSpec;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
 
 /**
  * Refaster templates related to expressions dealing with {@link
@@ -33,4 +40,54 @@ final class WebClientTemplates {
       return requestBodySpec.bodyValue(value);
     }
   }
+
+  static final class RetrieveArray<T> {
+    @BeforeTemplate
+    Flux<T> before(WebClient.ResponseSpec responseSpec) {
+      return responseSpec.bodyToMono(Refaster.<T[]>clazz()).flux().flatMap(Flux::fromArray);
+    }
+
+    @AfterTemplate
+    Flux<T> after(WebClient.ResponseSpec responseSpec) {
+      return responseSpec.bodyToFlux(Refaster.<T>clazz());
+    }
+  }
+
+  static final class RetrieveParameterizedTypeReference<T> {
+    @BeforeTemplate
+    Flux<T> before(
+        WebClient.ResponseSpec responseSpec,
+        ParameterizedTypeReference<? extends Collection<T>> clazz) {
+      return responseSpec.bodyToMono(clazz).flux().flatMapIterable(identity());
+    }
+
+    @AfterTemplate
+    Flux<T> after(WebClient.ResponseSpec responseSpec) {
+      return responseSpec.bodyToFlux(Refaster.<T>clazz());
+    }
+  }
+
+  static final class RetrieveSingle<T> {
+    @BeforeTemplate
+    Mono<T> before(Mono<T> mono, Class<T> clazz) {
+      return mono.flux().single();
+    }
+
+    @AfterTemplate
+    Mono<T> after(Mono<T> mono, Class<T> clazz) {
+      return mono.single();
+    }
+  }
+
+  static final class RetrieveSingleOrEmpty<T> {
+    @BeforeTemplate
+    Mono<T> before(Mono<T> mono, Class<T> clazz) {
+      return mono.flux().singleOrEmpty();
+    }
+
+    @AfterTemplate
+    Mono<T> after(Mono<T> mono) {
+      return mono;
+    }
+  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/bugpatterns/ImmutableListTemplatesTestInput.java

@@ -59,10 +59,6 @@ final class ImmutableListTemplatesTest implements RefasterTemplateTestCase {
         Stream.of(2).collect(collectingAndThen(toList(), ImmutableList::copyOf)));
   }
 
-  ImmutableList<Integer> testImmutableListAsList() {
-    return ImmutableList.of(1, 2, 3).asList();
-  }
-
   ImmutableSet<ImmutableList<Integer>> testImmutableListSortedCopyOf() {
     return ImmutableSet.of(
         ImmutableList.sortedCopyOf(naturalOrder(), ImmutableSet.of(1)),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/bugpatterns/ImmutableListTemplatesTestOutput.java

@@ -57,10 +57,6 @@ final class ImmutableListTemplatesTest implements RefasterTemplateTestCase {
         Stream.of(1).collect(toImmutableList()), Stream.of(2).collect(toImmutableList()));
   }
 
-  ImmutableList<Integer> testImmutableListAsList() {
-    return ImmutableList.of(1, 2, 3);
-  }
-
   ImmutableSet<ImmutableList<Integer>> testImmutableListSortedCopyOf() {
     return ImmutableSet.of(
         ImmutableList.sortedCopyOf(ImmutableSet.of(1)),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/bugpatterns/OptionalTemplatesTestInput.java

@@ -34,10 +34,6 @@ final class OptionalTemplatesTest implements RefasterTemplateTestCase {
     return Optional::get;
   }
 
-  Stream<Object> testOptionalToStream() {
-    return Stream.concat(Streams.stream(Optional.empty()), Streams.stream(Optional.of("foo")));
-  }
-
   ImmutableSet<Optional<String>> testOptionalFirstIteratorElement() {
     return ImmutableSet.of(
         ImmutableSet.of("foo").iterator().hasNext()

error-prone-contrib/src/test/resources/tech/picnic/errorprone/bugpatterns/OptionalTemplatesTestOutput.java

@@ -34,10 +34,6 @@ final class OptionalTemplatesTest implements RefasterTemplateTestCase {
     return Optional::orElseThrow;
   }
 
-  Stream<Object> testOptionalToStream() {
-    return Stream.concat(Optional.empty().stream(), Optional.of("foo").stream());
-  }
-
   ImmutableSet<Optional<String>> testOptionalFirstIteratorElement() {
     return ImmutableSet.of(
         stream(ImmutableSet.of("foo").iterator()).findFirst(),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/bugpatterns/WebClientTemplatesTestInput.java

@@ -1,15 +1,25 @@
 package tech.picnic.errorprone.bugpatterns;
 
+import static java.util.function.Function.identity;
 import static org.springframework.web.reactive.function.BodyInserters.fromValue;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.test.web.reactive.server.WebTestClient;
 import org.springframework.web.reactive.function.client.WebClient;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
 
 final class WebClientTemplatesTest implements RefasterTemplateTestCase {
   @Override
   public ImmutableSet<?> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(fromValue(""));
+    return ImmutableSet.of(
+        fromValue(""),
+        identity(),
+        Flux.class,
+        ImmutableList.class,
+        ParameterizedTypeReference.class);
   }
 
   ImmutableSet<?> testBodyValue() {
@@ -17,4 +27,30 @@ final class WebClientTemplatesTest implements RefasterTemplateTestCase {
         WebClient.create("foo").post().body(fromValue("bar")),
         WebTestClient.bindToServer().build().post().body(fromValue("bar")));
   }
+
+  public void testBodyToFluxValue() {
+    WebClient.create("foo")
+        .get()
+        .retrieve()
+        .bodyToMono(Integer[].class)
+        .flux()
+        .flatMap(Flux::fromArray);
+  }
+
+  public void testOther() {
+    WebClient.create("foo")
+        .get()
+        .retrieve()
+        .bodyToMono(new ParameterizedTypeReference<ImmutableList<String>>() {})
+        .flux()
+        .flatMapIterable(identity());
+  }
+
+  public void testCase3() {
+    Mono.empty().flux().single();
+  }
+
+  public void testCase4() {
+    Mono.empty().flux().singleOrEmpty();
+  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/bugpatterns/WebClientTemplatesTestOutput.java

@@ -1,15 +1,25 @@
 package tech.picnic.errorprone.bugpatterns;
 
+import static java.util.function.Function.identity;
 import static org.springframework.web.reactive.function.BodyInserters.fromValue;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.test.web.reactive.server.WebTestClient;
 import org.springframework.web.reactive.function.client.WebClient;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
 
 final class WebClientTemplatesTest implements RefasterTemplateTestCase {
   @Override
   public ImmutableSet<?> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(fromValue(""));
+    return ImmutableSet.of(
+        fromValue(""),
+        identity(),
+        Flux.class,
+        ImmutableList.class,
+        ParameterizedTypeReference.class);
   }
 
   ImmutableSet<?> testBodyValue() {
@@ -17,4 +27,20 @@ final class WebClientTemplatesTest implements RefasterTemplateTestCase {
         WebClient.create("foo").post().bodyValue("bar"),
         WebTestClient.bindToServer().build().post().bodyValue("bar"));
   }
+
+  public void testBodyToFluxValue() {
+    WebClient.create("foo").get().retrieve().bodyToFlux(Integer.class);
+  }
+
+  public void testOther() {
+    WebClient.create("foo").get().retrieve().bodyToFlux(String.class);
+  }
+
+  public void testCase3() {
+    Mono.empty().single();
+  }
+
+  public void testCase4() {
+    Mono.empty();
+  }
 }

pom.xml

@@ -126,6 +126,7 @@
         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>1.0</version.auto-service>
+        <version.auto-value>1.8.2</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>2.9.0</version.error-prone-orig>
@@ -203,10 +204,15 @@
                 <artifactId>auto-service-annotations</artifactId>
                 <version>${version.auto-service}</version>
             </dependency>
+            <dependency>
+                <groupId>com.google.auto.value</groupId>
+                <artifactId>auto-value</artifactId>
+                <version>${version.auto-value}</version>
+            </dependency>
             <dependency>
                 <groupId>com.google.auto.value</groupId>
                 <artifactId>auto-value-annotations</artifactId>
-                <version>1.8.2</version>
+                <version>${version.auto-value}</version>
             </dependency>
             <!-- Specified as a workaround for
             https://github.com/mojohaus/versions-maven-plugin/issues/244. -->
@@ -235,7 +241,7 @@
             <dependency>
                 <groupId>com.google.guava</groupId>
                 <artifactId>guava-bom</artifactId>
-                <version>30.1.1-jre</version>
+                <version>31.0-jre</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
@@ -324,7 +330,7 @@
             <dependency>
                 <groupId>org.assertj</groupId>
                 <artifactId>assertj-core</artifactId>
-                <version>3.20.2</version>
+                <version>3.21.0</version>
             </dependency>
             <dependency>
                 <groupId>org.checkerframework</groupId>
@@ -339,7 +345,7 @@
             <dependency>
                 <groupId>org.junit</groupId>
                 <artifactId>junit-bom</artifactId>
-                <version>5.8.0</version>
+                <version>5.8.1</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
@@ -743,7 +749,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-enforcer-plugin</artifactId>
-                    <version>3.0.0-M3</version>
+                    <version>3.0.0</version>
                     <configuration>
                         <fail>false</fail>
                         <rules>
@@ -780,7 +786,7 @@
                         <dependency>
                             <groupId>org.codehaus.mojo</groupId>
                             <artifactId>extra-enforcer-rules</artifactId>
-                            <version>1.3</version>
+                            <version>1.4</version>
                         </dependency>
                     </dependencies>
                     <executions>