KotlinPlugin: Setup default 'dependsOn' edges for Android source sets

libraries/tools/kotlin-gradle-plugin/build.gradle.kts

@@ -53,7 +53,7 @@ dependencies {
     compile("com.google.code.gson:gson:${rootProject.extra["versions.jar.gson"]}")
     compile("de.undercouch:gradle-download-task:4.0.2")
     implementation("com.github.gundy:semver4j:0.16.4")
-    
+
     compileOnly("com.android.tools.build:gradle:2.0.0")
     compileOnly("com.android.tools.build:gradle-core:2.0.0")
     compileOnly("com.android.tools.build:builder:2.0.0")
@@ -79,8 +79,9 @@ dependencies {
     compileOnly("com.android.tools.build:gradle:3.0.0") { isTransitive = false }
     compileOnly("com.android.tools.build:gradle-core:3.0.0") { isTransitive = false }
     compileOnly("com.android.tools.build:builder-model:3.0.0") { isTransitive = false }
+    testImplementation("com.android.tools.build:gradle:4.0.1")
 
-    testCompile(intellijDep()) { includeJars( "junit", "serviceMessages", rootProject = rootProject) }
+    testCompile(intellijDep()) { includeJars("junit", "serviceMessages", rootProject = rootProject) }
 
     testCompileOnly(project(":compiler"))
     testCompile(projectTests(":kotlin-build-common"))
@@ -103,7 +104,7 @@ runtimeJar(rewriteDefaultJarDepsToShadedCompiler()).configure {
 
     from {
         jarContents.asFileTree.map {
-            if (it.endsWith(".jar")) zipTree(it) 
+            if (it.endsWith(".jar")) zipTree(it)
             else it
         }
     }

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

@@ -774,6 +774,7 @@ abstract class AbstractAndroidProjectHandler(private val kotlinConfigurationTool
             val kotlinSourceSet = project.kotlinExtension.sourceSets.maybeCreate(
                 kotlinSourceSetNameForAndroidSourceSet(kotlinAndroidTarget, sourceSet.name)
             ).apply {
+                createDefaultDependsOnEdges(kotlinAndroidTarget, sourceSet, this)
                 kotlin.srcDir(project.file(project.file("src/${sourceSet.name}/kotlin")))
                 kotlin.srcDirs(sourceSet.java.srcDirs)
             }
@@ -845,6 +846,21 @@ abstract class AbstractAndroidProjectHandler(private val kotlinConfigurationTool
         }
     }
 
+    private fun createDefaultDependsOnEdges(
+        kotlinAndroidTarget: KotlinAndroidTarget,
+        androidSourceSet: AndroidSourceSet,
+        kotlinSourceSet: KotlinSourceSet
+    ) {
+        val commonSourceSetName = when (androidSourceSet.name) {
+            "main" -> "commonMain"
+            "test" -> "commonTest"
+            "androidTest" -> "commonTest"
+            else -> return
+        }
+        val commonSourceSet = kotlinAndroidTarget.project.kotlinExtension.sourceSets.findByName(commonSourceSetName) ?: return
+        kotlinSourceSet.dependsOn(commonSourceSet)
+    }
+
     /**
      * The Android variants have their configurations extendsFrom relation set up in a way that only some of the configurations of the
      * variants propagate the dependencies from production variants to test ones. To make this dependency propagation work for the Kotlin
@@ -961,14 +977,6 @@ abstract class AbstractAndroidProjectHandler(private val kotlinConfigurationTool
 
         // Register the source only after the task is created, because the task is required for that:
         compilation.source(defaultSourceSet)
-
-        // In MPPs, add the common main Kotlin sources to non-test variants, the common test sources to test variants
-        val commonSourceSetName = if (getTestedVariantData(variantData) == null)
-            KotlinSourceSet.COMMON_MAIN_SOURCE_SET_NAME else
-            KotlinSourceSet.COMMON_TEST_SOURCE_SET_NAME
-        project.kotlinExtension.sourceSets.findByName(commonSourceSetName)?.let {
-            compilation.source(it)
-        }
     }
 
     private fun postprocessVariant(

libraries/tools/kotlin-gradle-plugin/src/test/kotlin/org/jetbrains/kotlin/gradle/targets/android/KotlinAndroidDependsOnEdgesTest.kt

@@ -0,0 +1,108 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.gradle.targets.android
+
+import com.android.build.gradle.LibraryExtension
+import org.gradle.api.internal.project.ProjectInternal
+import org.gradle.testfixtures.ProjectBuilder
+import org.jetbrains.kotlin.gradle.dsl.KotlinMultiplatformExtension
+import org.jetbrains.kotlin.gradle.dsl.kotlinExtension
+import org.jetbrains.kotlin.gradle.plugin.KotlinSourceSet
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class KotlinAndroidDependsOnEdgesTest {
+    @Test
+    fun `default android source set declares dependsOn commonMain`() {
+        val project = ProjectBuilder.builder().build()
+        project.plugins.apply("kotlin-multiplatform")
+        project.plugins.apply("android-library")
+
+        /* Arbitrary minimal Android setup */
+        val android = project.extensions.getByName("android") as LibraryExtension
+        android.compileSdkVersion(30)
+
+        /* Minimal MPP setup */
+        val kotlin = project.kotlinExtension as KotlinMultiplatformExtension
+        kotlin.android("android")
+
+        /* Force evaluation */
+        project as ProjectInternal
+        project.evaluate()
+
+        val commonMain = kotlin.sourceSets.getByName("commonMain")
+        val commonTest = kotlin.sourceSets.getByName("commonTest")
+        val androidMain = kotlin.sourceSets.getByName("androidMain")
+        val androidTest = kotlin.sourceSets.getByName("androidTest")
+        val androidAndroidTest = kotlin.sourceSets.getByName("androidAndroidTest")
+
+        assertEquals(
+            setOf(commonMain), androidMain.dependsOn,
+            "Expected androidMain to dependOn commonMain"
+        )
+
+        assertEquals(
+            setOf(commonTest), androidTest.dependsOn,
+            "Expected androidTest to dependOn commonTest"
+        )
+
+        assertEquals(
+            setOf(commonTest), androidAndroidTest.dependsOn,
+            "Expected androidAndroidTest to dependOn commonTest"
+        )
+    }
+
+    @Test
+    fun `custom dependsOn edges`() {
+        val project = ProjectBuilder.builder().build()
+        project.plugins.apply("kotlin-multiplatform")
+        project.plugins.apply("android-library")
+
+        /* Arbitrary minimal Android setup */
+        val android = project.extensions.getByName("android") as LibraryExtension
+        android.compileSdkVersion(30)
+
+        /* Custom MPP setup */
+        val kotlin = project.kotlinExtension as KotlinMultiplatformExtension
+        kotlin.android("android")
+        kotlin.sourceSets.apply {
+            val jvmMain = create("jvmMain") {
+                it.dependsOn(getByName("commonMain"))
+            }
+            getByName("androidMain") {
+                it.dependsOn(jvmMain)
+            }
+        }
+
+        /* Force evaluation */
+        project as ProjectInternal
+        project.evaluate()
+
+        val commonMain = kotlin.sourceSets.getByName("commonMain")
+        val commonTest = kotlin.sourceSets.getByName("commonTest")
+        val jvmMain = kotlin.sourceSets.getByName("jvmMain")
+        val androidMain = kotlin.sourceSets.getByName("androidMain")
+        val androidTest = kotlin.sourceSets.getByName("androidTest")
+        val androidAndroidTest = kotlin.sourceSets.getByName("androidAndroidTest")
+
+        assertEquals(
+            setOf(commonMain, jvmMain).sorted(), androidMain.dependsOn.sorted(),
+            "Expected androidMain to depend on commonMain and jvmMain"
+        )
+
+        assertEquals(
+            setOf(commonTest), androidTest.dependsOn,
+            "Expected androidTest to only depend on commonTest"
+        )
+
+        assertEquals(
+            setOf(commonTest), androidAndroidTest.dependsOn,
+            "Expected androidAndroidTest to only depend on commonTest"
+        )
+    }
+}
+
+private fun Iterable<KotlinSourceSet>.sorted() = this.sortedBy { it.name }