Fix for androidTest variants of Android Gradle build.

Added a workaround reflection call to TaskManager to create a
javac task since it is missing for androidTest variants with jack.
Added source configuration with the tested variant to make
the tested sources visible to the compiler.

#KT-16434 Fixed

(cherry picked from commit 84efd05)

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

@@ -3,8 +3,11 @@ package org.jetbrains.kotlin.gradle.plugin
 import com.android.build.gradle.BaseExtension
 import com.android.build.gradle.BasePlugin
 import com.android.build.gradle.api.AndroidSourceSet
+import com.android.build.gradle.internal.TaskContainerAdaptor
+import com.android.build.gradle.internal.TaskManager
 import com.android.build.gradle.internal.variant.BaseVariantData
 import com.android.build.gradle.internal.variant.BaseVariantOutputData
+import com.android.build.gradle.internal.variant.TestVariantData
 import com.android.builder.model.SourceProvider
 import groovy.lang.Closure
 import org.gradle.api.InvalidUserDataException
@@ -31,6 +34,7 @@ import org.jetbrains.kotlin.gradle.internal.initKapt
 import org.jetbrains.kotlin.gradle.plugin.android.AndroidGradleWrapper
 import org.jetbrains.kotlin.gradle.plugin.android.KotlinJillTask
 import org.jetbrains.kotlin.gradle.tasks.*
+import org.jetbrains.kotlin.gradle.utils.getDeclaredFieldInHierarchy
 import org.jetbrains.kotlin.incremental.configureMultiProjectIncrementalCompilation
 import org.jetbrains.kotlin.incremental.multiproject.ArtifactDifferenceRegistryProviderAndroidWrapper
 import java.io.File
@@ -369,6 +373,22 @@ internal open class KotlinAndroidPlugin(
         }
     }
 
+    private fun forceCreateJavacTask(project: Project,
+                                     androidPlugin: BasePlugin,
+                                     variantData: BaseVariantData<*>): JavaCompile? {
+        val taskManager = androidPlugin::class.java.getDeclaredFieldInHierarchy("taskManager")
+                ?.let { it.isAccessible = true; it[androidPlugin] as TaskManager }
+        if (taskManager == null) {
+            log.kotlinDebug("TaskManager was not found, possibly, an incompatible Android Gradle plugin version is used.")
+            return null
+        }
+        val taskContainerAdaptor = TaskContainerAdaptor(project.tasks)
+        return taskManager.createJavacTask(taskContainerAdaptor, variantData.scope)?.get(taskContainerAdaptor)
+    }
+
+    private fun getTestedVariantData(variantData: BaseVariantData<*>): BaseVariantData<*>? =
+            ((variantData as? TestVariantData)?.testedVariantData as? BaseVariantData<*>)
+
     private fun processVariantData(
             variantDataList: List<BaseVariantData<out BaseVariantOutputData>>,
             project: Project,
@@ -384,7 +404,12 @@ internal open class KotlinAndroidPlugin(
             val variantDataName = variantData.name
             logger.kotlinDebug("Process variant [$variantDataName]")
 
-            val javaTask = AndroidGradleWrapper.getJavaTask(variantData)
+            val testedVariantData = getTestedVariantData(variantData)
+            val isAndroidTestVariant = variantDataName.endsWith("androidTest", ignoreCase = true) &&
+                                       testedVariantData != null
+
+            val javaTask = AndroidGradleWrapper.getJavaTask(variantData) ?:
+                           (if (isAndroidTestVariant) forceCreateJavacTask(project, androidPlugin, variantData) else null)
 
             if (javaTask == null) {
                 logger.info("KOTLIN: javaTask is missing for $variantDataName, so Kotlin files won't be compiled for it")
@@ -446,6 +471,10 @@ internal open class KotlinAndroidPlugin(
             }
 
             configureSources(kotlinTask, variantData)
+            if (isAndroidTestVariant) {
+                configureSources(kotlinTask, testedVariantData!!)
+            }
+
             if (kotlinAfterJavaTask != null) {
                 configureSources(kotlinAfterJavaTask, variantData)
             }

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

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.gradle.utils
+
+import java.lang.reflect.Field
+
+internal fun Class<*>.getDeclaredFieldInHierarchy(name: String): Field? {
+    val inheritanceChain = generateSequence(this) { it.superclass }
+    return inheritanceChain.map {
+        try {
+            it.getDeclaredField(name)
+        } catch (_: NoSuchFieldException) {
+            null
+        }
+    }.filterNotNull().first()
+}