Gradle: compile tests incrementally when main is changed

#KT-17674 fixed

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/KotlinGradlePluginIT.kt

@@ -20,10 +20,7 @@ import org.gradle.api.logging.LogLevel
 import com.intellij.openapi.util.io.FileUtil
 import org.jetbrains.kotlin.gradle.plugin.CopyClassesToJavaOutputStatus
 import org.jetbrains.kotlin.gradle.tasks.USING_INCREMENTAL_COMPILATION_MESSAGE
-import org.jetbrains.kotlin.gradle.util.checkBytecodeContains
-import org.jetbrains.kotlin.gradle.util.getFileByName
-import org.jetbrains.kotlin.gradle.util.getFilesByNames
-import org.jetbrains.kotlin.gradle.util.modify
+import org.jetbrains.kotlin.gradle.util.*
 import org.junit.Test
 import java.io.File
 import java.util.zip.ZipFile
@@ -490,6 +487,27 @@ class KotlinGradleIT: BaseGradleIT() {
         }
     }
 
+    @Test
+    fun testIncrementalTestCompile() {
+        val project = Project("kotlinProject", GRADLE_VERSION)
+        val options = defaultBuildOptions().copy(incremental = true)
+
+        project.build("build", options = options) {
+            assertSuccessful()
+        }
+
+        val joinerKt = project.projectDir.getFileByName("KotlinGreetingJoiner.kt")
+        joinerKt.modify {
+            it.replace("class KotlinGreetingJoiner", "internal class KotlinGreetingJoiner")
+        }
+
+        project.build("build", options = options) {
+            assertSuccessful()
+            val testJoinerKt = project.projectDir.getFileByName("TestKotlinGreetingJoiner.kt")
+            assertCompiledKotlinSources(project.relativize(joinerKt, testJoinerKt))
+        }
+    }
+
     @Test
     fun testLanguageVersionApiVersionExplicit() {
         val project = Project("kotlinProject", "3.3")

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/TestRootAffectedIT.kt

@@ -1,15 +1,13 @@
 package org.jetbrains.kotlin.gradle
 
-import org.jetbrains.kotlin.gradle.util.allKotlinFiles
 import org.jetbrains.kotlin.gradle.util.getFileByName
 import org.jetbrains.kotlin.gradle.util.modify
 import org.junit.Test
-import java.io.File
 
 class TestRootAffectedIT : BaseGradleIT() {
     @Test
     fun testSourceRootClassIsModifiedIC() {
-        val project = Project("kotlinProject", "2.10")
+        val project = Project("kotlinProject", "4.1")
         val buildOptions = defaultBuildOptions().copy(incremental = true)
 
         project.build("build", options = buildOptions) {
@@ -26,8 +24,8 @@ class TestRootAffectedIT : BaseGradleIT() {
 
         project.build("build", options = buildOptions) {
             assertSuccessful()
-            val expectedToCompile = project.relativize(listOf(kotlinGreetingJoinerFile) + project.allTestKotlinFiles())
-            assertCompiledKotlinSources(expectedToCompile)
+            val testKotlinGreetingJoinerFile = project.projectDir.getFileByName("TestKotlinGreetingJoiner.kt")
+            assertCompiledKotlinSources(project.relativize(kotlinGreetingJoinerFile, testKotlinGreetingJoinerFile))
         }
 
         project.build("build", options = buildOptions) {
@@ -38,7 +36,8 @@ class TestRootAffectedIT : BaseGradleIT() {
 
     @Test
     fun testSourceRootClassIsRemovedIC() {
-        val project = Project("kotlinProject", "2.10")
+        // todo: update Gradle after https://github.com/gradle/gradle/issues/3051 is resolved
+        val project = Project("kotlinProject", "3.0")
         val buildOptions = defaultBuildOptions().copy(incremental = true)
 
         project.build("build", options = buildOptions) {
@@ -48,12 +47,6 @@ class TestRootAffectedIT : BaseGradleIT() {
         val dummyFile = project.projectDir.getFileByName("Dummy.kt")
         dummyFile.delete()
 
-        project.build("build", options = buildOptions) {
-            assertSuccessful()
-            val expectedToCompile = project.relativize(project.allTestKotlinFiles())
-            assertCompiledKotlinSources(expectedToCompile)
-        }
-
         project.build("build", options = buildOptions) {
             assertSuccessful()
             assertCompiledKotlinSources(emptyList())
@@ -62,7 +55,7 @@ class TestRootAffectedIT : BaseGradleIT() {
 
     @Test
     fun testTestRootClassIsRemovedIC() {
-        val project = Project("kotlinProject", "2.10")
+        val project = Project("kotlinProject", "4.1")
         val buildOptions = defaultBuildOptions().copy(incremental = true)
 
         project.build("build", options = buildOptions) {
@@ -76,13 +69,5 @@ class TestRootAffectedIT : BaseGradleIT() {
             assertSuccessful()
             assertCompiledKotlinSources(emptyList())
         }
-
-        project.build("build", options = buildOptions) {
-            assertSuccessful()
-            assertCompiledKotlinSources(emptyList())
-        }
     }
-
-    private fun Project.allTestKotlinFiles(): Iterable<File> =
-            File(projectDir, "src/test").allKotlinFiles()
 }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/compilerRunner/GradleCompilerEnvironment.kt

@@ -36,5 +36,7 @@ internal class GradleIncrementalCompilerEnvironment(
         compilerArgs: CommonCompilerArguments,
         val kaptAnnotationsFileUpdater: AnnotationFileUpdater? = null,
         val artifactDifferenceRegistryProvider: ArtifactDifferenceRegistryProvider? = null,
-        val artifactFile: File? = null
+        val artifactFile: File? = null,
+        val buildHistoryFile: File? = null,
+        val friendBuildHistoryFile: File? = null
 ) : GradleCompilerEnvironment(compilerClasspath, messageCollector, outputItemsCollector, compilerArgs)

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/compilerRunner/GradleKotlinCompilerRunner.kt

@@ -255,7 +255,9 @@ internal class GradleCompilerRunner(private val project: Project) : KotlinCompil
                 reportSeverity = reportSeverity(verbose),
                 requestedCompilationResults = arrayOf(CompilationResultCategory.IC_COMPILE_ITERATION.code),
                 compilerMode = CompilerMode.INCREMENTAL_COMPILER,
-                targetPlatform = targetPlatform
+                targetPlatform = targetPlatform,
+                resultDifferenceFile = environment.buildHistoryFile,
+                friendDifferenceFile = environment.friendBuildHistoryFile
         )
         val servicesFacade = GradleIncrementalCompilerServicesFacadeImpl(project, environment)
         val argsArray = ArgumentUtils.convertArgumentsToStringList(environment.compilerArgs).toTypedArray()

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/Tasks.kt

@@ -243,6 +243,7 @@ open class KotlinCompile : AbstractKotlinCompile<K2JVMCompilerArguments>(), Kotl
     internal open val sourceRootsContainer = FilteringSourceRootsContainer()
 
     private var kaptAnnotationsFileUpdater: AnnotationFileUpdater? = null
+    val buildHistoryFile: File = File(taskBuildDirectory, "build-history.bin")
 
     val kaptOptions = KaptOptions()
 
@@ -316,10 +317,13 @@ open class KotlinCompile : AbstractKotlinCompile<K2JVMCompilerArguments>(), Kotl
             !incremental -> GradleCompilerEnvironment(computedCompilerClasspath, messageCollector, outputItemCollector, args)
             else -> {
                 logger.warn(USING_INCREMENTAL_COMPILATION_MESSAGE)
+                val friendTask = friendTaskName?.let { project.tasks.findByName(it) as? KotlinCompile }
                 GradleIncrementalCompilerEnvironment(computedCompilerClasspath, changedFiles, reporter, taskBuildDirectory,
                         messageCollector, outputItemCollector, args, kaptAnnotationsFileUpdater,
                         artifactDifferenceRegistryProvider,
-                        artifactFile)
+                        artifactFile = artifactFile,
+                        buildHistoryFile = buildHistoryFile,
+                        friendBuildHistoryFile = friendTask?.buildHistoryFile)
             }
         }