Move tests requiring TestKit to functionalTest source set (#4700)

* Move ConfigurationCacheSpec to functionalTest

* Move DetektAndroidSpec to functionalTest

* Move DetektMultiplatformSpec to functionalTest

* Move DetektPlainSpec to functionalTest

* Move GradleVersionSpec to functionalTest

* Move ReportMergeSpec to functionalTest

* Move DetektTaskDslSpec to functionalTest

* Move DetektJvmSpec tests that rely on TestKit to functionalTest

* Don't make TestKit available to `test` source set

* Exclude functionalTest sources from detekt rules that exclude test sources

There are TooManyFunctions and SpreadOperator violations in functionalTest
source set after the migration of rules from test source set in
detekt-gradle-plugin, so exclusions were added to align with existing
behavior.

config/detekt/detekt.yml

@@ -43,6 +43,8 @@ complexity:
     excludes: ['**/test/**', '**/*.Test.kt', '**/*.Spec.kt']
   MethodOverloading:
     active: true
+  TooManyFunctions:
+    excludes: ['**/test/**', '**/functionalTest/**']
 
 coroutines:
   active: true
@@ -129,6 +131,10 @@ naming:
   VariableMinLength:
     active: true
 
+performance:
+  SpreadOperator:
+    excludes: ['**/test/**', '**/functionalTest/**']
+
 potential-bugs:
   AvoidReferentialEquality:
     active: true

detekt-gradle-plugin/build.gradle.kts

@@ -90,10 +90,15 @@ gradlePlugin {
     testSourceSets(
         sourceSets["testFixtures"],
         sourceSets["functionalTest"],
-        sourceSets["test"]
     )
 }
 
+// Some functional tests reference internal functions in the Gradle plugin. This should become unnecessary as further
+// updates are made to the functional test suite.
+kotlin.target.compilations.getByName("functionalTest") {
+    associateWith(target.compilations.getByName("main"))
+}
+
 // Manually inject dependency to gradle-testkit since the default injected plugin classpath is from `main.runtime`.
 tasks.pluginUnderTestMetadata {
     pluginClasspath.from(pluginCompileOnly)

detekt-gradle-plugin/src/functionalTest/kotlin/io/gitlab/arturbosch/detekt/DetektJvmSpec.kt

@@ -0,0 +1,89 @@
+package io.gitlab.arturbosch.detekt
+
+import io.gitlab.arturbosch.detekt.testkit.DslGradleRunner
+import io.gitlab.arturbosch.detekt.testkit.ProjectLayout
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+
+class DetektJvmSpec {
+    @Nested
+    inner class `When applying detekt in a JVM project` {
+
+        @Nested
+        inner class `report location set on extension & task` {
+            val gradleRunner = DslGradleRunner(
+                projectLayout = ProjectLayout(numberOfSourceFilesInRootPerSourceDir = 1),
+                buildFileName = "build.gradle.kts",
+                mainBuildFileContent = """
+                    plugins {
+                        kotlin("jvm")
+                        id("io.gitlab.arturbosch.detekt")
+                    }
+
+                    repositories {
+                        mavenCentral()
+                        mavenLocal()
+                    }
+
+                    detekt {
+                        reports {
+                            txt.destination = file("output-path.txt")
+                        }
+                    }
+
+                    tasks.withType<io.gitlab.arturbosch.detekt.Detekt>().configureEach {
+                        reports {
+                            txt.destination = file("output-path2.txt")
+                        }
+                    }
+                """.trimIndent(),
+                dryRun = false
+            ).also {
+                it.setupProject()
+            }
+
+            @Test
+            fun `logs a warning`() {
+                gradleRunner.runTasksAndCheckResult(":detektMain") { buildResult ->
+                    assertThat(buildResult.output).contains("TXT report location set on detekt {} extension will be ignored for detektMain task.")
+                }
+            }
+        }
+
+        @Nested
+        inner class `report location set on task only` {
+            val gradleRunner = DslGradleRunner(
+                projectLayout = ProjectLayout(numberOfSourceFilesInRootPerSourceDir = 1),
+                buildFileName = "build.gradle.kts",
+                mainBuildFileContent = """
+                    plugins {
+                        kotlin("jvm")
+                        id("io.gitlab.arturbosch.detekt")
+                    }
+
+                    repositories {
+                        mavenCentral()
+                        mavenLocal()
+                    }
+
+                    tasks.withType<io.gitlab.arturbosch.detekt.Detekt>().configureEach {
+                        reports {
+                            txt.destination = file("output-path2.txt")
+                        }
+                    }
+                """.trimIndent(),
+                dryRun = false
+            ).also {
+                it.setupProject()
+            }
+
+            @Test
+            fun `logs a warning`() {
+                gradleRunner.runTasksAndCheckResult(":detektMain") { buildResult ->
+                    assertThat(buildResult.output).doesNotContain("report location set on detekt {} extension will be ignored")
+                }
+            }
+        }
+    }
+}

detekt-gradle-plugin/src/test/kotlin/io/gitlab/arturbosch/detekt/DetektJvmSpec.kt

@@ -64,81 +64,5 @@ class DetektJvmSpec {
                 assertThat(argumentString).contains("--classpath")
             }
         }
-
-        @Nested
-        inner class `report location set on extension & task` {
-            val gradleRunner = DslGradleRunner(
-                projectLayout = ProjectLayout(numberOfSourceFilesInRootPerSourceDir = 1),
-                buildFileName = "build.gradle.kts",
-                mainBuildFileContent = """
-                    plugins {
-                        kotlin("jvm")
-                        id("io.gitlab.arturbosch.detekt")
-                    }
-
-                    repositories {
-                        mavenCentral()
-                        mavenLocal()
-                    }
-
-                    detekt {
-                        reports {
-                            txt.destination = file("output-path.txt")
-                        }
-                    }
-
-                    tasks.withType<io.gitlab.arturbosch.detekt.Detekt>().configureEach {
-                        reports {
-                            txt.destination = file("output-path2.txt")
-                        }
-                    }
-                """.trimIndent(),
-                dryRun = false
-            ).also {
-                it.setupProject()
-            }
-
-            @Test
-            fun `logs a warning`() {
-                gradleRunner.runTasksAndCheckResult(":detektMain") { buildResult ->
-                    assertThat(buildResult.output).contains("TXT report location set on detekt {} extension will be ignored for detektMain task.")
-                }
-            }
-        }
-
-        @Nested
-        inner class `report location set on task only` {
-            val gradleRunner = DslGradleRunner(
-                projectLayout = ProjectLayout(numberOfSourceFilesInRootPerSourceDir = 1),
-                buildFileName = "build.gradle.kts",
-                mainBuildFileContent = """
-                    plugins {
-                        kotlin("jvm")
-                        id("io.gitlab.arturbosch.detekt")
-                    }
-
-                    repositories {
-                        mavenCentral()
-                        mavenLocal()
-                    }
-
-                    tasks.withType<io.gitlab.arturbosch.detekt.Detekt>().configureEach {
-                        reports {
-                            txt.destination = file("output-path2.txt")
-                        }
-                    }
-                """.trimIndent(),
-                dryRun = false
-            ).also {
-                it.setupProject()
-            }
-
-            @Test
-            fun `logs a warning`() {
-                gradleRunner.runTasksAndCheckResult(":detektMain") { buildResult ->
-                    assertThat(buildResult.output).doesNotContain("report location set on detekt {} extension will be ignored")
-                }
-            }
-        }
     }
 }