Common tests are discoverable via platform modules test classpath

Introduce KotlinGradleOrderEnumerationHandler
    and patch KotlinAndroidGradleOrderEnumerationHandler:
    - If 'Android Support' plugin is off KAndroidGradleOEH will not be available and KGOEH will be used
    - Make KAndroidGOEH implement a different EP so it replaces KGOEH when it is available

idea/idea-android/src/org/jetbrains/kotlin/android/KotlinAndroidGradleOrderEnumerationHandler.kt

@@ -11,13 +11,12 @@ import com.intellij.openapi.externalSystem.util.ExternalSystemApiUtil
 import com.intellij.openapi.module.Module
 import com.intellij.openapi.module.ModuleManager
 import com.intellij.openapi.roots.ModuleRootModel
+import com.intellij.openapi.roots.OrderEnumerationHandler
 import com.intellij.openapi.roots.OrderRootType
 import com.intellij.openapi.vfs.VfsUtilCore
-import org.jetbrains.kotlin.config.KotlinFacetSettingsProvider
+import org.jetbrains.kotlin.idea.caches.project.isMPPModule
 import org.jetbrains.kotlin.idea.core.isAndroidModule
 import org.jetbrains.kotlin.idea.facet.KotlinFacet
-import org.jetbrains.kotlin.platform.impl.isCommon
-import org.jetbrains.plugins.gradle.execution.GradleOrderEnumeratorHandler
 import org.jetbrains.plugins.gradle.model.ExternalSourceDirectorySet
 import org.jetbrains.plugins.gradle.service.project.data.ExternalProjectDataCache
 import org.jetbrains.plugins.gradle.util.GradleConstants
@@ -33,9 +32,7 @@ import java.io.File
    Everything works for Java-only projects because there's only a single classes directory,
    but Kotlin Gradle plugin adds a separate output directory, and it's not attached by default.
  */
-class AndroidGradleOrderEnumerationHandler(module: Module) : GradleOrderEnumeratorHandler(module) {
-    override fun shouldProcessDependenciesRecursively() = false
-
+class KotlinAndroidGradleOrderEnumerationHandler(private val module: Module) : OrderEnumerationHandler() {
     override fun addCustomModuleRoots(
         type: OrderRootType,
         rootModel: ModuleRootModel,
@@ -85,17 +82,11 @@ class AndroidGradleOrderEnumerationHandler(module: Module) : GradleOrderEnumerat
         return true
     }
 
-    class FactoryImpl : Factory() {
+    class FactoryImpl : OrderEnumerationHandler.Factory() {
         override fun isApplicable(module: Module): Boolean {
-            return ExternalSystemApiUtil.isExternalSystemAwareModule(GradleConstants.SYSTEM_ID, module)
-                    && !module.isMultiplatformModule()
+            return ExternalSystemApiUtil.isExternalSystemAwareModule(GradleConstants.SYSTEM_ID, module) && !module.isMPPModule
         }
 
-        override fun createHandler(module: Module) = AndroidGradleOrderEnumerationHandler(module)
+        override fun createHandler(module: Module) = KotlinAndroidGradleOrderEnumerationHandler(module)
     }
-}
-
-private fun Module.isMultiplatformModule(): Boolean {
-    val settings = KotlinFacetSettingsProvider.getInstance(project).getInitializedSettings(this)
-    return settings.platform.isCommon || settings.implementedModuleNames.isNotEmpty()
 }

idea/idea-gradle/src/org/jetbrains/kotlin/idea/gradle/execution/KotlinGradleOrderEnumerationHandler.kt

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. 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.idea.gradle.execution
+
+import com.intellij.openapi.module.Module
+import org.jetbrains.kotlin.idea.caches.project.isMPPModule
+import org.jetbrains.plugins.gradle.execution.GradleOrderEnumeratorHandler
+
+open class KotlinGradleOrderEnumerationHandler(module: Module) : GradleOrderEnumeratorHandler(module) {
+    override fun shouldIncludeTestsFromDependentModulesToTestClasspath(): Boolean {
+        return true
+    }
+
+    open class Factory : GradleOrderEnumeratorHandler.FactoryImpl() {
+        override fun isApplicable(module: Module): Boolean {
+            return module.isMPPModule
+        }
+
+        override fun createHandler(module: Module) = KotlinGradleOrderEnumerationHandler(module)
+    }
+}

idea/src/META-INF/gradle-java.xml

@@ -61,8 +61,7 @@
 
         <runConfigurationProducer implementation="org.jetbrains.kotlin.idea.run.KotlinTestClassGradleConfigurationProducer"/>
         <runConfigurationProducer implementation="org.jetbrains.kotlin.idea.run.KotlinTestMethodGradleConfigurationProducer"/>
-
-        <orderEnumerationHandlerFactory implementation="org.jetbrains.kotlin.android.AndroidGradleOrderEnumerationHandler$FactoryImpl" order="first"/>
+        <orderEnumerationHandlerFactory implementation="org.jetbrains.kotlin.android.KotlinAndroidGradleOrderEnumerationHandler$FactoryImpl" order="first"/>
     </extensions>
 
     <extensions defaultExtensionNs="org.jetbrains.kotlin">

idea/src/META-INF/gradle-java.xml.as33

@@ -60,6 +60,7 @@
 
         <runConfigurationProducer implementation="org.jetbrains.kotlin.idea.run.KotlinTestClassGradleConfigurationProducer"/>
         <runConfigurationProducer implementation="org.jetbrains.kotlin.idea.run.KotlinTestMethodGradleConfigurationProducer"/>
+        <orderEnumerationHandlerFactory implementation="org.jetbrains.kotlin.android.KotlinAndroidGradleOrderEnumerationHandler$FactoryImpl" order="first"/>
 
     </extensions>
 

idea/src/META-INF/gradle.xml

@@ -11,6 +11,10 @@
         <buildSystemTypeDetector implementation="org.jetbrains.kotlin.idea.configuration.GradleDetector"/>
     </extensions>
 
+    <extensions defaultExtensionNs="org.jetbrains.plugins.gradle">
+        <orderEnumerationHandlerFactory implementation="org.jetbrains.kotlin.idea.gradle.execution.KotlinGradleOrderEnumerationHandler$Factory" order="first"/>
+    </extensions>
+
     <!-- NATIVE PART -->
     <application-components>
         <component>

idea/src/META-INF/gradle.xml.181

@@ -70,7 +70,7 @@
         <runConfigurationProducer implementation="org.jetbrains.kotlin.idea.run.KotlinTestClassGradleConfigurationProducer"/>
         <runConfigurationProducer implementation="org.jetbrains.kotlin.idea.run.KotlinTestMethodGradleConfigurationProducer"/>
 
-        <orderEnumerationHandlerFactory implementation="org.jetbrains.kotlin.android.AndroidGradleOrderEnumerationHandler$FactoryImpl" order="first"/>
+        <orderEnumerationHandlerFactory implementation="org.jetbrains.kotlin.android.KotlinAndroidGradleOrderEnumerationHandler$FactoryImpl" order="first"/>
     </extensions>
 
     <extensions defaultExtensionNs="org.jetbrains.kotlin">