Prevent init from invoking result.success() multiple times. (#298)

Prevent init from invoking result.success() multiple times.

packages/google_mobile_ads/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.13.2+1
+
+* Fixes [Issue #130](https://github.com/googleads/googleads-mobile-flutter/issues/130)
+
 ## 0.13.2
 
 * Fixes a crash where [PlatformView.getView() returns null](https://github.com/googleads/googleads-mobile-flutter/issues/46)

packages/google_mobile_ads/android/src/main/java/io/flutter/plugins/googlemobileads/Constants.java

@@ -17,5 +17,5 @@
 /** Constants used in the plugin. */
 public class Constants {
   /** Version request agent. Should be bumped alongside plugin versions. */
-  public static final String REQUEST_AGENT_PREFIX_VERSIONED = "Flutter-GMA-0.13.2";
+  public static final String REQUEST_AGENT_PREFIX_VERSIONED = "Flutter-GMA-0.13.2+1";
 }

packages/google_mobile_ads/android/src/main/java/io/flutter/plugins/googlemobileads/FlutterMobileAdsWrapper.java

@@ -0,0 +1,32 @@
+// Copyright 2021 Google LLC
+//
+// 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
+//
+// https://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 io.flutter.plugins.googlemobileads;
+
+import android.content.Context;
+import androidx.annotation.NonNull;
+import com.google.android.gms.ads.MobileAds;
+import com.google.android.gms.ads.initialization.OnInitializationCompleteListener;
+
+/** A wrapper around static methods in {@link com.google.android.gms.ads.MobileAds}. */
+public class FlutterMobileAdsWrapper {
+
+  public FlutterMobileAdsWrapper() {}
+
+  /** Initializes the sdk. */
+  public void initialize(
+      @NonNull Context context, @NonNull OnInitializationCompleteListener listener) {
+    MobileAds.initialize(context, listener);
+  }
+}

packages/google_mobile_ads/android/src/main/java/io/flutter/plugins/googlemobileads/GoogleMobileAdsPlugin.java

@@ -60,19 +60,24 @@ private static <T> T requireNonNull(T obj) {
   @Nullable private AdInstanceManager instanceManager;
   @Nullable private ActivityPluginBinding activityBinding;
   private final Map<String, NativeAdFactory> nativeAdFactories = new HashMap<>();
-
+  private final FlutterMobileAdsWrapper flutterMobileAds;
   /**
    * Public constructor for the plugin. Dependency initialization is handled in lifecycle methods
    * below.
    */
-  public GoogleMobileAdsPlugin() {}
+  public GoogleMobileAdsPlugin() {
+    this.flutterMobileAds = new FlutterMobileAdsWrapper();
+  }
 
   /** Constructor for testing. */
   @VisibleForTesting
   protected GoogleMobileAdsPlugin(
-      @Nullable FlutterPluginBinding pluginBinding, @Nullable AdInstanceManager instanceManager) {
+      @Nullable FlutterPluginBinding pluginBinding,
+      @Nullable AdInstanceManager instanceManager,
+      @NonNull FlutterMobileAdsWrapper flutterMobileAds) {
     this.pluginBinding = pluginBinding;
     this.instanceManager = instanceManager;
+    this.flutterMobileAds = flutterMobileAds;
   }
 
   /**
@@ -226,14 +231,8 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull final Result result)
         break;
 
       case "MobileAds#initialize":
-        MobileAds.initialize(
-            instanceManager.activity,
-            new OnInitializationCompleteListener() {
-              @Override
-              public void onInitializationComplete(InitializationStatus initializationStatus) {
-                result.success(new FlutterInitializationStatus(initializationStatus));
-              }
-            });
+        flutterMobileAds.initialize(
+            instanceManager.activity, new FlutterInitializationListener(result));
         break;
       case "MobileAds#updateRequestConfiguration":
         RequestConfiguration.Builder builder = MobileAds.getRequestConfiguration().toBuilder();
@@ -394,4 +393,28 @@ public void onInitializationComplete(InitializationStatus initializationStatus)
         result.notImplemented();
     }
   }
+
+  /** An {@link OnInitializationCompleteListener} that invokes result.success() at most once. */
+  private static final class FlutterInitializationListener
+      implements OnInitializationCompleteListener {
+
+    private final Result result;
+    private boolean isInitializationCompleted;
+
+    private FlutterInitializationListener(@NonNull final Result result) {
+      this.result = result;
+      isInitializationCompleted = false;
+    }
+
+    @Override
+    public void onInitializationComplete(@NonNull InitializationStatus initializationStatus) {
+      // Make sure not to invoke this more than once, since Dart will throw an exception if success
+      // is invoked more than once. See b/193418432.
+      if (isInitializationCompleted) {
+        return;
+      }
+      result.success(new FlutterInitializationStatus(initializationStatus));
+      isInitializationCompleted = true;
+    }
+  }
 }

packages/google_mobile_ads/android/src/test/java/io/flutter/plugins/googlemobileads/GoogleMobileAdsTest.java

@@ -28,10 +28,13 @@
 import static org.mockito.Mockito.verify;
 
 import android.app.Activity;
+import android.content.Context;
 import android.os.Bundle;
 import com.google.android.gms.ads.AdError;
 import com.google.android.gms.ads.AdapterResponseInfo;
 import com.google.android.gms.ads.ResponseInfo;
+import com.google.android.gms.ads.initialization.InitializationStatus;
+import com.google.android.gms.ads.initialization.OnInitializationCompleteListener;
 import com.google.android.gms.ads.nativead.NativeAd;
 import com.google.android.gms.ads.nativead.NativeAdView;
 import io.flutter.plugin.common.BinaryMessenger;
@@ -499,7 +502,8 @@ public void internalInitDisposesAds() {
 
     // Check that ads are removed and disposed when "_init" is called.
     AdInstanceManager testManagerSpy = spy(testManager);
-    GoogleMobileAdsPlugin plugin = new GoogleMobileAdsPlugin(null, testManagerSpy);
+    GoogleMobileAdsPlugin plugin =
+        new GoogleMobileAdsPlugin(null, testManagerSpy, new FlutterMobileAdsWrapper());
     Result result = mock(Result.class);
     MethodCall methodCall = new MethodCall("_init", null);
     plugin.onMethodCall(methodCall, result);
@@ -514,6 +518,35 @@ public void internalInitDisposesAds() {
     assertNull(testManager.adIdFor(banner));
   }
 
+  @Test
+  public void initializeCallbackInvokedTwice() {
+    AdInstanceManager testManagerSpy = spy(testManager);
+    FlutterMobileAdsWrapper mockMobileAds = mock(FlutterMobileAdsWrapper.class);
+    GoogleMobileAdsPlugin plugin = new GoogleMobileAdsPlugin(null, testManagerSpy, mockMobileAds);
+    final InitializationStatus mockInitStatus = mock(InitializationStatus.class);
+    doAnswer(
+            new Answer() {
+              @Override
+              public Object answer(InvocationOnMock invocation) {
+                // Invoke init listener twice.
+                OnInitializationCompleteListener listener = invocation.getArgument(1);
+                listener.onInitializationComplete(mockInitStatus);
+                listener.onInitializationComplete(mockInitStatus);
+                return null;
+              }
+            })
+        .when(mockMobileAds)
+        .initialize(
+            ArgumentMatchers.any(Context.class),
+            ArgumentMatchers.any(OnInitializationCompleteListener.class));
+
+    MethodCall methodCall = new MethodCall("MobileAds#initialize", null);
+    Result result = mock(Result.class);
+    plugin.onMethodCall(methodCall, result);
+
+    verify(result).success(ArgumentMatchers.any(FlutterInitializationStatus.class));
+  }
+
   @Test(expected = IllegalArgumentException.class)
   public void trackAdThrowsErrorForDuplicateId() {
     final FlutterBannerAd banner = mock(FlutterBannerAd.class);

packages/google_mobile_ads/ios/Classes/FLTConstants.h

@@ -13,4 +13,4 @@
 // limitations under the License.
 
 /** Versioned request agent string. */
-#define FLT_REQUEST_AGENT_VERSIONED @"Flutter-GMA-0.13.2"
+#define FLT_REQUEST_AGENT_VERSIONED @"Flutter-GMA-0.13.2+1"

packages/google_mobile_ads/ios/Classes/FLTGoogleMobileAdsPlugin.m

@@ -19,6 +19,36 @@ @interface FLTGoogleMobileAdsPlugin ()
 @property NSMutableDictionary<NSString *, id<FLTNativeAdFactory>> *nativeAdFactories;
 @end
 
+/// Initialization handler for GMASDK. Invokes result at most once.
+@interface FLTInitializationHandler : NSObject
+- (instancetype)initWithResult:(FlutterResult)result;
+- (void)handleInitializationComplete:(GADInitializationStatus *_Nonnull)status;
+@end
+
+@implementation FLTInitializationHandler {
+  FlutterResult _result;
+  BOOL _isInitializationCompleted;
+}
+
+- (instancetype)initWithResult:(FlutterResult)result {
+  self = [super init];
+  if (self) {
+    _isInitializationCompleted = false;
+    _result = result;
+  }
+  return self;
+}
+
+- (void)handleInitializationComplete:(GADInitializationStatus *_Nonnull)status {
+  if (_isInitializationCompleted) {
+    return;
+  }
+  _result([[FLTInitializationStatus alloc] initWithStatus:status]);
+  _isInitializationCompleted = true;
+}
+
+@end
+
 @implementation FLTGoogleMobileAdsPlugin {
   NSMutableDictionary<NSString *, id<FLTNativeAdFactory>> *_nativeAdFactories;
   FLTAdInstanceManager *_manager;
@@ -97,9 +127,10 @@ - (void)handleMethodCall:(FlutterMethodCall *)call result:(FlutterResult)result
       UIApplication.sharedApplication.delegate.window.rootViewController;
 
   if ([call.method isEqualToString:@"MobileAds#initialize"]) {
+    FLTInitializationHandler *handler = [[FLTInitializationHandler alloc] initWithResult:result];
     [[GADMobileAds sharedInstance]
         startWithCompletionHandler:^(GADInitializationStatus *_Nonnull status) {
-          result([[FLTInitializationStatus alloc] initWithStatus:status]);
+          [handler handleInitializationComplete:status];
         }];
   } else if ([call.method isEqualToString:@"_init"]) {
     [_manager disposeAllAds];

packages/google_mobile_ads/ios/Tests/FLTGoogleMobileAdsPluginMethodCallsTest.m

@@ -108,6 +108,35 @@ - (void)testInternalInit {
   OCMVerify([_mockAdInstanceManager disposeAllAds]);
 }
 
+- (void)testMobileAdsInitialize {
+  id gadMobileAdsClassMock = OCMClassMock([GADMobileAds class]);
+  OCMStub(ClassMethod([gadMobileAdsClassMock sharedInstance]))
+      .andReturn((GADMobileAds *)gadMobileAdsClassMock);
+  GADInitializationStatus *mockInitStatus = OCMClassMock([GADInitializationStatus class]);
+  OCMStub([mockInitStatus adapterStatusesByClassName]).andReturn(@{});
+  OCMStub([gadMobileAdsClassMock startWithCompletionHandler:[OCMArg any]])
+      .andDo(^(NSInvocation *invocation) {
+        // Invoke the init handler twice.
+        GADInitializationCompletionHandler completionHandler;
+        [invocation getArgument:&completionHandler atIndex:2];
+        completionHandler(mockInitStatus);
+        completionHandler(mockInitStatus);
+      });
+
+  FlutterMethodCall *methodCall =
+      [FlutterMethodCall methodCallWithMethodName:@"MobileAds#initialize" arguments:@{}];
+  __block int resultInvokedCount = 0;
+  __block id _Nullable returnedResult;
+  FlutterResult result = ^(id _Nullable result) {
+    resultInvokedCount += 1;
+    returnedResult = result;
+  };
+
+  [_fltGoogleMobileAdsPlugin handleMethodCall:methodCall result:result];
+  XCTAssertEqual(resultInvokedCount, 1);
+  XCTAssertEqual([((FLTInitializationStatus *)returnedResult) adapterStatuses].count, 0);
+}
+
 - (void)testSetSameAppKeyEnabledYes {
   id gadMobileAdsClassMock = OCMClassMock([GADMobileAds class]);
   OCMStub(ClassMethod([gadMobileAdsClassMock sharedInstance]))

packages/google_mobile_ads/pubspec.yaml

@@ -16,7 +16,7 @@ name: google_mobile_ads
 description: Flutter plugin for Google Mobile Ads, supporting
   banner, interstitial (full-screen),  rewarded and native ads
 homepage: https://github.com/googleads/googleads-mobile-flutter/tree/master/packages/google_mobile_ads
-version: 0.13.2
+version: 0.13.2+1
 
 flutter:
   plugin: