A mechanism for listening to lifecycle events in RNTA

android/app/build.gradle

@@ -10,19 +10,16 @@ def hermesEngineDir =
 def hermesAndroidDir = "$hermesEngineDir/android"
 
 buildscript {
-    ext.kotlinVersion = "1.4.20"
-
-    def buildscriptDir = buildscript.sourceFile.getParent()
-    apply from: "$buildscriptDir/../test-app-util.gradle"
+    def androidDir = "${buildscript.sourceFile.getParent()}/../"
+    apply from: "$androidDir/test-app-util.gradle"
+    apply from: "$androidDir/dependencies.gradle"
 
     repositories {
-        google()
         jcenter()
     }
 
     dependencies {
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion"
-        classpath "com.android.tools.build:gradle:4.0.2"
     }
 }
 
@@ -45,15 +42,15 @@ apply from: file("${testAppDir}/test-app.gradle")
 applyTestAppModule(project, "com.microsoft.reacttestapp")
 
 project.ext.react = [
-    appName: getAppName(),
+    appName      : getAppName(),
     applicationId: getApplicationId(),
     enableFlipper: getFlipperVersion(rootDir),
     enableHermes : true,
 ]
 
 android {
-    compileSdkVersion 29
-    buildToolsVersion "29.0.3"
+    compileSdkVersion sdk.version
+    buildToolsVersion sdk.buildToolsVersion
 
     // TODO: Remove this block when minSdkVersion >= 24. See
     // https://stackoverflow.com/q/53402639 for details.
@@ -69,10 +66,10 @@ android {
 
     defaultConfig {
         applicationId project.ext.react.applicationId
-        minSdkVersion 21
-        targetSdkVersion 29
-        versionCode 1
-        versionName "1.0"
+        minSdkVersion sdk.minVersion
+        targetSdkVersion sdk.version
+        versionCode rntaVersion.code
+        versionName rntaVersion.label
 
         resValue "string", "app_name", project.ext.react.appName
 
@@ -94,6 +91,8 @@ android {
 }
 
 dependencies {
+    implementation project(":support")
+
     implementation "com.google.dagger:dagger:2.28.3"
     implementation "com.google.dagger:dagger-android:2.28.3"
     implementation "com.google.dagger:dagger-android-support:2.28.3"

android/app/src/main/java/com/microsoft/reacttestapp/TestApp.kt

@@ -1,9 +1,11 @@
 package com.microsoft.reacttestapp
 
 import android.app.Application
+import com.facebook.react.PackageList
 import com.facebook.react.ReactApplication
 import com.microsoft.reacttestapp.di.DaggerTestAppComponent
 import com.microsoft.reacttestapp.react.TestAppReactNativeHost
+import com.microsoft.reacttestapp.support.ReactTestAppLifecycleEvents
 import dagger.android.AndroidInjector
 import dagger.android.DispatchingAndroidInjector
 import dagger.android.HasAndroidInjector
@@ -20,13 +22,25 @@ class TestApp : Application(), HasAndroidInjector, ReactApplication {
     override fun onCreate() {
         super.onCreate()
 
+        val eventConsumers = PackageList(this).packages
+            .filter { it is ReactTestAppLifecycleEvents }
+            .map { it as ReactTestAppLifecycleEvents }
+
+        eventConsumers.forEach { it.onTestAppInitialized() }
+
         val testAppComponent = DaggerTestAppComponent.builder()
             .binds(this)
             .build()
-
         testAppComponent.inject(this)
 
-        reactNativeHostInternal.init()
+        reactNativeHostInternal.init(
+            beforeReactNativeInit = {
+                eventConsumers.forEach { it.onTestAppWillInitializeReactNative() }
+            },
+            afterReactNativeInit = {
+                eventConsumers.forEach { it.onTestAppDidInitializeReactNative() }
+            },
+        )
     }
 
     override fun androidInjector(): AndroidInjector<Any> = dispatchingAndroidInjector

android/app/src/main/java/com/microsoft/reacttestapp/react/TestAppReactNativeHost.kt

@@ -59,11 +59,24 @@ class TestAppReactNativeHost @Inject constructor(
 
     var onBundleSourceChanged: ((newSource: BundleSource) -> Unit)? = null
 
-    fun init() {
+    fun init(beforeReactNativeInit: () -> Unit, afterReactNativeInit: () -> Unit) {
         if (BuildConfig.DEBUG && hasInstance()) {
             error("init() can only be called once on startup")
         }
 
+        val reactInstanceListener = object : ReactInstanceManager.ReactInstanceEventListener {
+            override fun onReactContextInitialized(context: ReactContext?) {
+                afterReactNativeInit()
+
+                // proactively removing the listener to avoid leaking memory
+                // and to avoid dupe calls to afterReactNativeInit()
+                reactInstanceManager.removeReactInstanceEventListener(this)
+            }
+        }
+
+        reactInstanceManager.addReactInstanceEventListener(reactInstanceListener)
+
+        beforeReactNativeInit()
         SoLoader.init(application, false)
         reactInstanceManager.createReactContextInBackground()
 

android/build.gradle

@@ -0,0 +1,13 @@
+buildscript {
+    repositories {
+        jcenter()
+        google()
+    }
+
+    def buildscriptDir = buildscript.sourceFile.getParent()
+    apply from: "$buildscriptDir/dependencies.gradle"
+
+    dependencies {
+        classpath "com.android.tools.build:gradle:$androidPluginVersion"
+    }
+}

android/dependencies.gradle

@@ -0,0 +1,15 @@
+ext {
+    androidPluginVersion = "4.0.2"
+    kotlinVersion = "1.4.20"
+
+    rntaVersion = [
+        code : 1,
+        label: "1.0"
+    ]
+
+    sdk = [
+        version          : 29,
+        minVersion       : 21,
+        buildToolsVersion: "29.0.3"
+    ]
+}

android/react-native-build.gradle

@@ -1,10 +1,14 @@
 buildscript {
+    def buildscriptDir = buildscript.sourceFile.getParent()
+    apply from: "$buildscriptDir/dependencies.gradle"
+
     repositories {
         google()
         jcenter()
     }
+
     dependencies {
-        classpath 'com.android.tools.build:gradle:4.0.1'
+        classpath "com.android.tools.build:gradle:$androidPluginVersion"
         classpath 'de.undercouch:gradle-download-task:4.1.1'
     }
 }

android/settings.gradle

@@ -1,2 +1,2 @@
 rootProject.name='react-test-app'
-include ':app'
+include ':app', ':support'

android/support/build.gradle

@@ -0,0 +1,26 @@
+repositories {
+    jcenter()
+    google()
+}
+
+apply plugin: "com.android.library"
+
+def androidDir = "${buildscript.sourceFile.getParent()}/../"
+apply from: "$androidDir/dependencies.gradle"
+
+android {
+    compileSdkVersion sdk.version
+    buildToolsVersion sdk.buildToolsVersion
+
+    defaultConfig {
+        minSdkVersion sdk.minVersion
+        targetSdkVersion sdk.version
+        versionCode rntaVersion.code
+        versionName rntaVersion.label
+    }
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+}

android/support/src/main/AndroidManifest.xml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest package="com.microsoft.reacttestapp.support" />

android/support/src/main/java/com/microsoft/reacttestapp/support/ReactTestAppLifecycleEvents.java

@@ -0,0 +1,7 @@
+package com.microsoft.reacttestapp.support;
+
+public interface ReactTestAppLifecycleEvents {
+    void onTestAppInitialized();
+    void onTestAppWillInitializeReactNative();
+    void onTestAppDidInitializeReactNative();
+}

example/android/build.gradle

@@ -1 +1,12 @@
-// Top-level build file where you can add configuration options common to all sub-projects/modules.
+buildscript {
+    apply from: file("../node_modules/react-native-test-app/android/dependencies.gradle")
+
+    repositories {
+        jcenter()
+        google()
+    }
+
+    dependencies {
+        classpath "com.android.tools.build:gradle:$androidPluginVersion"
+    }
+}

example/ios/ExampleTests/DevSupportTests.m

@@ -17,6 +17,8 @@ @implementation DevSupportTests
 - (void)testDevSupportIsLinked
 {
     XCTAssertNotNil(ReactTestAppDidInitializeNotification);
+    XCTAssertNotNil(ReactTestAppWillInitializeReactNativeNotification);
+    XCTAssertNotNil(ReactTestAppDidInitializeReactNativeNotification);
     XCTAssertNotNil(ReactTestAppSceneDidOpenURLNotification);
 }
 

ios/ReactTestApp/AppDelegate.swift

@@ -23,6 +23,14 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
                      didFinishLaunchingWithOptions _: [UIApplication.LaunchOptionsKey: Any]?) -> Bool
     {
         self.application = application
+
+        defer {
+            NotificationCenter.default.post(
+                name: .ReactTestAppDidInitialize,
+                object: nil
+            )
+        }
+
         return true
     }
 

ios/ReactTestApp/Public/ReactTestApp-DevSupport.h

@@ -10,6 +10,8 @@
 NS_ASSUME_NONNULL_BEGIN
 
 extern NSNotificationName const ReactTestAppDidInitializeNotification;
+extern NSNotificationName const ReactTestAppWillInitializeReactNativeNotification;
+extern NSNotificationName const ReactTestAppDidInitializeReactNativeNotification;
 extern NSNotificationName const ReactTestAppSceneDidOpenURLNotification;
 
 NS_ASSUME_NONNULL_END

ios/ReactTestApp/ReactInstance.swift

@@ -97,6 +97,13 @@ final class ReactInstance: NSObject, RCTBridgeDelegate {
     }
 
     func initReact(onDidInitialize: @escaping () -> Void) {
+        if bridge == nil {
+            NotificationCenter.default.post(
+                name: .ReactTestAppWillInitializeReactNative,
+                object: nil
+            )
+        }
+
         if let bridge = bridge {
             if remoteBundleURL == nil {
                 // When loading the embedded bundle, we must disable remote
@@ -109,7 +116,7 @@ final class ReactInstance: NSObject, RCTBridgeDelegate {
             self.bridge = bridge
 
             NotificationCenter.default.post(
-                name: .ReactTestAppDidInitialize,
+                name: .ReactTestAppDidInitializeReactNative,
                 object: bridge
             )
 

ios/ReactTestApp/ReactTestApp-DevSupport.m

@@ -9,5 +9,9 @@
 
 NSNotificationName const ReactTestAppDidInitializeNotification =
     @"ReactTestAppDidInitializeNotification";
+NSNotificationName const ReactTestAppWillInitializeReactNativeNotification =
+    @"ReactTestAppWillInitializeReactNativeNotification";
+NSNotificationName const ReactTestAppDidInitializeReactNativeNotification =
+    @"ReactTestAppDidInitializeReactNativeNotification";
 NSNotificationName const ReactTestAppSceneDidOpenURLNotification =
     @"ReactTestAppSceneDidOpenURLNotification";

plopfile.js

@@ -299,6 +299,11 @@ module.exports = (/** @type {import("plop").NodePlopAPI} */ plop) => {
           path: `${prefix}gradlew.bat`,
           templateFile: path.join(androidTemplateDir, "gradlew.bat"),
         });
+        actions.push({
+          type: "add",
+          path: `${prefix}build.gradle`,
+          templateFile: path.join(androidTemplateDir, "build.gradle"),
+        });
         actions.push({
           type: "add",
           path: `${prefix}settings.gradle`,

test-app.gradle

@@ -17,8 +17,12 @@ private static void apply(Settings settings) {
     }
 
     settings.include(":app")
+    settings.include(":support")
+
     settings.project(":app")
         .projectDir = new File("${projectDir}/android/app")
+    settings.project(":support")
+        .projectDir = new File("${projectDir}/android/support")
 }
 
 def scriptDir = buildscript.sourceFile.getParent()