Use automatic plugin classpath injection for tests. (google#374)

This change migrates to use GradleRunner's automatic classpath injection for code under test.

- Removed unnecessary gradle/groovy dependencies from plugin's build.gradle, as the Java Gradle Plugin development plugin already does so.

- Removed createClasspathManifest and the corresponding bridging code in test project setup.

- As mentioned in its documentation, automatic classpath inject only works if the plugin under test is applied using the plugins DSL.

- Previously we inject Kotlin dependency by putting it on testProjectRuntime and adding to the test project's classpath via classpath manifest. Now we set this in TestProjectBuilder.

- Refactored methods for building Android test project.

build.gradle

@@ -51,52 +51,18 @@ configurations {
     testProjectRuntime
 }
 
-/**
- * Write file containing all the things that should be in the test projects' class path. This
- * includes the current SNAPSHOT version of protobuf-gradle-plugin and whatever else may be
- * needed by the test projects such as other plugins or libraries.
- */
-task createClasspathManifest {
-    def outputDir = file("$buildDir/$name")
-
-    inputs.files sourceSets.main.runtimeClasspath
-    inputs.files configurations.testProjectRuntime
-    outputs.dir outputDir
-
-    doLast {
-        outputDir.mkdirs()
-        file("$outputDir/plugin-classpath.txt").text = inputs.files.join("\n")
-    }
-}
-
 dependencies {
-    compileOnly gradleApi()
-    compileOnly localGroovy()
     compileOnly "org.gradle:gradle-kotlin-dsl:1.0.4"
 
     compile 'com.google.guava:guava:27.0.1-jre'
     compile 'com.google.gradle:osdetector-gradle-plugin:1.6.2'
     compile 'commons-lang:commons-lang:2.6'
 
-    testCompile gradleTestKit()
-    testCompile gradleApi()
-    testCompile localGroovy()
     testCompile 'junit:junit:4.12'
     testCompile ('org.spockframework:spock-core:1.0-groovy-2.4') {
       exclude module : 'groovy-all'
     }
     testCompile 'commons-io:commons-io:2.5'
-
-    // This kotlin version needs to be compatible with the 
-    // android plugin being used in the test runtime.
-    testProjectRuntime "org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.20"
-
-    // Add android plugin to the test classpath, so that we can jump into class definitions,
-    // read their sources, set break points, etc while debugging android unit tests.
-    // Change the version if necessary to match the specific unit test.
-    testRuntime 'com.android.tools.build:gradle:2.3.0'
-    // Add the classpath file to the test runtime classpath
-    testRuntime files(createClasspathManifest)
 }
 
 test.inputs.files fileTree("$projectDir/testProject")

src/test/groovy/com/google/protobuf/gradle/AndroidProjectDetectionTest.groovy

@@ -11,7 +11,6 @@ import spock.lang.Unroll
  * Verify android projects are identified correctly
  */
 class AndroidProjectDetectionTest extends Specification {
-  // Current supported version is Android plugin 3.3.0+.
   private static final List<String> GRADLE_VERSION = ["5.6"]
   private static final List<String> ANDROID_PLUGIN_VERSION = ["3.5.0"]
 
@@ -32,13 +31,13 @@ class AndroidProjectDetectionTest extends Specification {
     given: "a project with android plugin"
     File mainProjectDir = ProtobufPluginTestHelper.projectBuilder("singleModuleAndroidProject")
        .copyDirs('testProjectAndroid', 'testProjectAndroidBare')
+       .withAndroidPlugin(agpVersion)
        .build()
     appendUtilIsAndroidProjectCheckTask(new File(mainProjectDir, "build.gradle"), true)
 
     when: "checkForAndroidPlugin task evaluates Utils.isAndroidProject"
     BuildResult result = buildAndroidProject(
        mainProjectDir,
-       agpVersion,
        gradleVersion,
        "checkForAndroidPlugin"
     )
@@ -64,13 +63,13 @@ class AndroidProjectDetectionTest extends Specification {
     File mainProjectDir = ProtobufPluginTestHelper.projectBuilder("rootModuleAndroidProject")
        .copyDirs('testProjectAndroid', 'testProjectAndroidBare')
        .copySubProjects(subProjectStaging)
+       .withAndroidPlugin(agpVersion)
        .build()
     appendUtilIsAndroidProjectCheckTask(new File(mainProjectDir, "build.gradle"), true)
 
     when: "checkForAndroidPlugin task evaluates Utils.isAndroidProject"
     BuildResult result = buildAndroidProject(
        mainProjectDir,
-            agpVersion,
        gradleVersion,
        "checkForAndroidPlugin"
     )

src/test/groovy/com/google/protobuf/gradle/ProtobufAndroidPluginTest.groovy

@@ -13,6 +13,7 @@ import spock.lang.Unroll
 class ProtobufAndroidPluginTest extends Specification {
   private static final List<String> GRADLE_VERSION = ["5.6"]
   private static final List<String> ANDROID_PLUGIN_VERSION = ["3.5.0"]
+  private static final List<String> KOTLIN_VERSION = ["1.3.20"]
 
   @Unroll
   void "testProjectAndroid should be successfully executed [android #agpVersion, gradle #gradleVersion]"() {
@@ -28,11 +29,11 @@ class ProtobufAndroidPluginTest extends Specification {
         .build()
     File mainProjectDir = ProtobufPluginTestHelper.projectBuilder('testProjectAndroidMain')
         .copySubProjects(testProjectStaging, testProjectLiteStaging, testProjectAndroidStaging)
+        .withAndroidPlugin(agpVersion)
         .build()
     when: "build is invoked"
     BuildResult result = buildAndroidProject(
        mainProjectDir,
-       agpVersion,
        gradleVersion,
        "testProjectAndroid:build"
     )
@@ -46,7 +47,7 @@ class ProtobufAndroidPluginTest extends Specification {
   }
 
   @Unroll
-  void "testProjectAndroidKotlin should be successfully executed [android #agpVersion, gradle #gradleVersion]"() {
+  void "testProjectAndroidKotlin [android #agpVersion, gradle #gradleVersion, kotlin #kotlinVersion]"() {
     given: "project from testProject, testProjectLite & testProjectAndroid"
     File testProjectStaging = ProtobufPluginTestHelper.projectBuilder('testProject')
         .copyDirs('testProjectBase', 'testProject')
@@ -59,11 +60,12 @@ class ProtobufAndroidPluginTest extends Specification {
         .build()
     File mainProjectDir = ProtobufPluginTestHelper.projectBuilder('testProjectAndroidMain')
         .copySubProjects(testProjectStaging, testProjectLiteStaging, testProjectAndroidStaging)
+        .withAndroidPlugin(agpVersion)
+        .withKotlin(kotlinVersion)
         .build()
     when: "build is invoked"
     BuildResult result = buildAndroidProject(
        mainProjectDir,
-       agpVersion,
        gradleVersion,
        "testProjectAndroid:build"
     )
@@ -74,5 +76,6 @@ class ProtobufAndroidPluginTest extends Specification {
     where:
     agpVersion << ANDROID_PLUGIN_VERSION
     gradleVersion << GRADLE_VERSION
+    kotlinVersion << KOTLIN_VERSION
   }
 }

src/test/groovy/com/google/protobuf/gradle/ProtobufJavaPluginTest.groovy

@@ -15,6 +15,7 @@ import spock.lang.Unroll
 class ProtobufJavaPluginTest extends Specification {
   // Current supported version is Gradle 5+.
   private static final List<String> GRADLE_VERSIONS = ["5.6", "6.0"]
+  private static final List<String> KOTLIN_VERSIONS = ["1.3.20", "1.3.30"]
 
   void "testApplying java and com.google.protobuf adds corresponding task to project"() {
     given: "a basic project with java and com.google.protobuf"
@@ -61,6 +62,7 @@ class ProtobufJavaPluginTest extends Specification {
     BuildResult result = GradleRunner.create()
       .withProjectDir(projectDir)
       .withArguments('build', '--stacktrace')
+      .withPluginClasspath()
       .withGradleVersion(gradleVersion)
       .forwardStdOutput(new OutputStreamWriter(System.out))
       .forwardStdError(new OutputStreamWriter(System.err))
@@ -86,6 +88,7 @@ class ProtobufJavaPluginTest extends Specification {
     BuildResult result = GradleRunner.create()
             .withProjectDir(projectDir)
             .withArguments('build', '--stacktrace')
+            .withPluginClasspath()
             .withGradleVersion(gradleVersion)
             .forwardStdOutput(new OutputStreamWriter(System.out))
             .forwardStdError(new OutputStreamWriter(System.err))
@@ -100,16 +103,18 @@ class ProtobufJavaPluginTest extends Specification {
   }
 
   @Unroll
-  void "testProjectKotlin should be successfully executed (kotlin-only project) [gradle #gradleVersion]"() {
+  void "testProjectKotlin (kotlin-only project) [gradle #gradleVersion, kotlin #kotlinVersion]"() {
     given: "project from testProjectKotlin overlaid on testProject"
     File projectDir = ProtobufPluginTestHelper.projectBuilder('testProjectKotlin')
         .copyDirs('testProjectBase', 'testProjectKotlin')
+        .withKotlin(kotlinVersion)
         .build()
 
     when: "build is invoked"
     BuildResult result = GradleRunner.create()
       .withProjectDir(projectDir)
       .withArguments('build', '--stacktrace')
+      .withPluginClasspath()
       .withDebug(true)
       .withGradleVersion(gradleVersion)
       .build()
@@ -120,19 +125,22 @@ class ProtobufJavaPluginTest extends Specification {
 
     where:
     gradleVersion << GRADLE_VERSIONS
+    kotlinVersion << KOTLIN_VERSIONS
   }
 
   @Unroll
-  void "testProjectJavaAndKotlin should be successfully executed (java+kotlin project) [gradle #gradleVersion]"() {
+  void "testProjectJavaAndKotlin (java+kotlin project) [gradle #gradleVersion, kotlin #kotlinVersion]"() {
     given: "project from testProjecJavaAndKotlin overlaid on testProjectKotlin, testProject"
     File projectDir = ProtobufPluginTestHelper.projectBuilder('testProjectJavaAndKotlin')
         .copyDirs('testProjectBase', 'testProject', 'testProjectKotlin', 'testProjectJavaAndKotlin')
+        .withKotlin(kotlinVersion)
         .build()
 
     when: "build is invoked"
     BuildResult result = GradleRunner.create()
       .withProjectDir(projectDir)
       .withArguments('build')
+      .withPluginClasspath()
       .withDebug(true)
       .withGradleVersion(gradleVersion)
       .build()
@@ -143,6 +151,7 @@ class ProtobufJavaPluginTest extends Specification {
 
     where:
     gradleVersion << GRADLE_VERSIONS
+    kotlinVersion << KOTLIN_VERSIONS
   }
 
   @Unroll
@@ -156,6 +165,7 @@ class ProtobufJavaPluginTest extends Specification {
     BuildResult result = GradleRunner.create()
       .withProjectDir(projectDir)
       .withArguments('build', '--stacktrace')
+      .withPluginClasspath()
       .withGradleVersion(gradleVersion)
       .forwardStdOutput(new OutputStreamWriter(System.out))
       .forwardStdError(new OutputStreamWriter(System.err))
@@ -187,6 +197,7 @@ class ProtobufJavaPluginTest extends Specification {
     BuildResult result = GradleRunner.create()
       .withProjectDir(mainProjectDir)
       .withArguments('testProjectDependent:build', '--stacktrace')
+      .withPluginClasspath()
       .withGradleVersion(gradleVersion)
       .forwardStdOutput(new OutputStreamWriter(System.out))
       .forwardStdError(new OutputStreamWriter(System.err))
@@ -211,6 +222,7 @@ class ProtobufJavaPluginTest extends Specification {
     BuildResult result = GradleRunner.create()
             .withProjectDir(projectDir)
             .withArguments('build', '--stacktrace')
+            .withPluginClasspath()
             .withGradleVersion(gradleVersion)
             .forwardStdOutput(new OutputStreamWriter(System.out))
             .forwardStdError(new OutputStreamWriter(System.err))
@@ -243,6 +255,7 @@ class ProtobufJavaPluginTest extends Specification {
     BuildResult result = GradleRunner.create()
             .withProjectDir(mainProjectDir)
             .withArguments('testProjectDependentApp:build', '--stacktrace')
+            .withPluginClasspath()
             .withGradleVersion(gradleVersion)
             .forwardStdOutput(new OutputStreamWriter(System.out))
             .forwardStdError(new OutputStreamWriter(System.err))
@@ -267,6 +280,7 @@ class ProtobufJavaPluginTest extends Specification {
     BuildResult result = GradleRunner.create()
       .withProjectDir(projectDir)
       .withArguments('build', '--stacktrace')
+      .withPluginClasspath()
       .withGradleVersion(gradleVersion)
       .forwardStdOutput(new OutputStreamWriter(System.out))
       .forwardStdError(new OutputStreamWriter(System.err))
@@ -291,6 +305,7 @@ class ProtobufJavaPluginTest extends Specification {
     BuildResult result = GradleRunner.create()
       .withProjectDir(projectDir)
       .withArguments('idea')
+      .withPluginClasspath()
       .withGradleVersion(gradleVersion)
       .build()
 

src/test/groovy/com/google/protobuf/gradle/ProtobufKotlinDslPluginTest.groovy

@@ -24,6 +24,7 @@ class ProtobufKotlinDslPluginTest extends Specification {
     BuildResult result = GradleRunner.create()
       .withProjectDir(projectDir)
       .withArguments('build', '--stacktrace')
+      .withPluginClasspath()
       .withGradleVersion(gradleVersion)
       .forwardStdOutput(new OutputStreamWriter(System.out))
       .forwardStdError(new OutputStreamWriter(System.err))