watch leaking support library fragments and their views

build.gradle

@@ -34,6 +34,7 @@ buildscript {
       mockito_kotlin: 'com.nhaarman:mockito-kotlin-kt1.1:1.5.0',
       okio: 'com.squareup.okio:okio:2.2.2',
       robolectric   : 'org.robolectric:robolectric:4.0-alpha-3',
+      android_support: 'com.android.support:support-v4:28.0.0'
   ]
   repositories {
     google()

leakcanary-object-watcher-android-support-fragments/build.gradle

@@ -0,0 +1,25 @@
+apply plugin: 'com.android.library'
+apply plugin: 'kotlin-android'
+
+dependencies {
+  api project(':leakcanary-object-watcher-android')
+
+  implementation deps.kotlin.stdlib
+  // Optional dependency
+  compileOnly deps.android_support
+}
+
+android {
+  compileSdkVersion versions.compileSdk
+  defaultConfig {
+    minSdkVersion versions.minSdk
+    consumerProguardFiles 'consumer-proguard-rules.pro'
+  }
+  lintOptions {
+    disable 'GoogleAppIndexingWarning'
+    error 'ObsoleteSdkInt'
+    check 'Interoperability'
+  }
+}
+
+apply from: rootProject.file('gradle/gradle-mvn-push.gradle')

leakcanary-object-watcher-android-support-fragments/consumer-proguard-rules.pro

@@ -0,0 +1,2 @@
+# AndroidSupportFragmentDestroyWatcher is loaded via reflection
+-keep class leakcanary.internal.AndroidSupportFragmentDestroyWatcher { *; }

leakcanary-object-watcher-android-support-fragments/gradle.properties

@@ -0,0 +1,3 @@
+POM_ARTIFACT_ID=leakcanary-object-watcher-android-support-fragments
+POM_NAME=LeakCanary Object Watcher for Android extension: Android support library fragments support
+POM_PACKAGING=aar

leakcanary-object-watcher-android-support-fragments/src/main/AndroidManifest.xml

@@ -0,0 +1,2 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.squareup.leakcanary.fragments.android_support" />

leakcanary-object-watcher-android-support-fragments/src/main/java/leakcanary/internal/AndroidSupportFragmentDestroyWatcher.kt

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2018 Square, Inc.
+ *
+ * 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 leakcanary.internal
+
+import android.app.Activity
+import android.support.v4.app.Fragment
+import android.support.v4.app.FragmentActivity
+import android.support.v4.app.FragmentManager
+import leakcanary.AppWatcher.Config
+import leakcanary.ObjectWatcher
+
+internal class AndroidSupportFragmentDestroyWatcher(
+  private val objectWatcher: ObjectWatcher,
+  private val configProvider: () -> Config
+) : (Activity) -> Unit {
+
+  private val fragmentLifecycleCallbacks = object : FragmentManager.FragmentLifecycleCallbacks() {
+
+    override fun onFragmentViewDestroyed(
+      fm: FragmentManager,
+      fragment: Fragment
+    ) {
+      val view = fragment.view
+      if (view != null && configProvider().watchFragmentViews) {
+        objectWatcher.watch(view)
+      }
+    }
+
+    override fun onFragmentDestroyed(
+      fm: FragmentManager,
+      fragment: Fragment
+    ) {
+      if (configProvider().watchFragments) {
+        objectWatcher.watch(fragment)
+      }
+    }
+  }
+
+  override fun invoke(activity: Activity) {
+    if (activity is FragmentActivity) {
+      val supportFragmentManager = activity.supportFragmentManager
+      supportFragmentManager.registerFragmentLifecycleCallbacks(fragmentLifecycleCallbacks, true)
+    }
+  }
+}

leakcanary-object-watcher-android/src/main/java/leakcanary/internal/FragmentDestroyWatcher.kt

@@ -33,6 +33,10 @@ internal object FragmentDestroyWatcher {
   private const val ANDROIDX_FRAGMENT_DESTROY_WATCHER_CLASS_NAME =
     "leakcanary.internal.AndroidXFragmentDestroyWatcher"
 
+  private const val ANDROID_SUPPORT_FRAGMENT_CLASS_NAME = "android.support.v4.app.Fragment"
+  private const val ANDROID_SUPPORT_FRAGMENT_DESTROY_WATCHER_CLASS_NAME =
+    "leakcanary.internal.AndroidSupportFragmentDestroyWatcher"
+
   fun install(
     application: Application,
     objectWatcher: ObjectWatcher,
@@ -57,6 +61,17 @@ internal object FragmentDestroyWatcher {
       )
     }
 
+    if (classAvailable(ANDROID_SUPPORT_FRAGMENT_CLASS_NAME) &&
+        classAvailable(ANDROID_SUPPORT_FRAGMENT_DESTROY_WATCHER_CLASS_NAME)
+    ) {
+      val watcherConstructor = Class.forName(ANDROID_SUPPORT_FRAGMENT_DESTROY_WATCHER_CLASS_NAME)
+          .getDeclaredConstructor(ObjectWatcher::class.java, Function0::class.java)
+      @kotlin.Suppress("UNCHECKED_CAST")
+      fragmentDestroyWatchers.add(
+          watcherConstructor.newInstance(objectWatcher, configProvider) as (Activity) -> Unit
+      )
+    }
+
     if (fragmentDestroyWatchers.size == 0) {
       return
     }

settings.gradle

@@ -6,6 +6,7 @@ include ':leakcanary-android-sample'
 include ':leakcanary-object-watcher'
 include ':leakcanary-object-watcher-android'
 include ':leakcanary-object-watcher-android-androidx'
+include ':leakcanary-object-watcher-android-support-fragments'
 include ':shark'
 include ':shark-android'
 include ':shark-cli'