[in_app_purchase_android] Add UserChoiceBilling mode. (#6162)

Add UserChoiceBilling billing mode option. 

Fixes flutter/flutter/issues/143004 

Left in draft until: 

This does not have an End to end working example with play integration. I am currently stuck at the server side play integration part.

packages/in_app_purchase/in_app_purchase_android/CHANGELOG.md

@@ -1,5 +1,6 @@
-## NEXT
+## 0.3.2
 
+* Adds UserChoiceBilling APIs to platform addition.
 * Updates minimum supported SDK version to Flutter 3.13/Dart 3.1.
 
 ## 0.3.1

packages/in_app_purchase/in_app_purchase_android/android/src/main/java/io/flutter/plugins/inapppurchase/BillingClientFactory.java

@@ -6,7 +6,9 @@ package io.flutter.plugins.inapppurchase;
 
 import android.content.Context;
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import com.android.billingclient.api.BillingClient;
+import com.android.billingclient.api.UserChoiceBillingListener;
 import io.flutter.plugin.common.MethodChannel;
 
 /** Responsible for creating a {@link BillingClient} object. */
@@ -22,5 +24,8 @@ interface BillingClientFactory {
    * @return The {@link BillingClient} object that is created.
    */
   BillingClient createBillingClient(
-      @NonNull Context context, @NonNull MethodChannel channel, int billingChoiceMode);
+      @NonNull Context context,
+      @NonNull MethodChannel channel,
+      int billingChoiceMode,
+      @Nullable UserChoiceBillingListener userChoiceBillingListener);
 }

packages/in_app_purchase/in_app_purchase_android/android/src/main/java/io/flutter/plugins/inapppurchase/BillingClientFactoryImpl.java

@@ -6,7 +6,10 @@ package io.flutter.plugins.inapppurchase;
 
 import android.content.Context;
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import com.android.billingclient.api.BillingClient;
+import com.android.billingclient.api.UserChoiceBillingListener;
+import io.flutter.Log;
 import io.flutter.plugin.common.MethodChannel;
 import io.flutter.plugins.inapppurchase.MethodCallHandlerImpl.BillingChoiceMode;
 
@@ -15,11 +18,34 @@ final class BillingClientFactoryImpl implements BillingClientFactory {
 
   @Override
   public BillingClient createBillingClient(
-      @NonNull Context context, @NonNull MethodChannel channel, int billingChoiceMode) {
+      @NonNull Context context,
+      @NonNull MethodChannel channel,
+      int billingChoiceMode,
+      @Nullable UserChoiceBillingListener userChoiceBillingListener) {
     BillingClient.Builder builder = BillingClient.newBuilder(context).enablePendingPurchases();
-    if (billingChoiceMode == BillingChoiceMode.ALTERNATIVE_BILLING_ONLY) {
+    switch (billingChoiceMode) {
-      // https://developer.android.com/google/play/billing/alternative/alternative-billing-without-user-choice-in-app
+      case BillingChoiceMode.ALTERNATIVE_BILLING_ONLY:
-      builder.enableAlternativeBillingOnly();
+        // https://developer.android.com/google/play/billing/alternative/alternative-billing-without-user-choice-in-app
+        builder.enableAlternativeBillingOnly();
+        break;
+      case BillingChoiceMode.USER_CHOICE_BILLING:
+        if (userChoiceBillingListener != null) {
+          // https://developer.android.com/google/play/billing/alternative/alternative-billing-with-user-choice-in-app
+          builder.enableUserChoiceBilling(userChoiceBillingListener);
+        } else {
+          Log.e(
+              "BillingClientFactoryImpl",
+              "userChoiceBillingListener null when USER_CHOICE_BILLING set. Defaulting to PLAY_BILLING_ONLY");
+        }
+        break;
+      case BillingChoiceMode.PLAY_BILLING_ONLY:
+        // Do nothing.
+        break;
+      default:
+        Log.e(
+            "BillingClientFactoryImpl",
+            "Unknown BillingChoiceMode " + billingChoiceMode + ", Defaulting to PLAY_BILLING_ONLY");
+        break;
     }
     return builder.setListener(new PluginPurchaseListener(channel)).build();
   }

packages/in_app_purchase/in_app_purchase_android/android/src/main/java/io/flutter/plugins/inapppurchase/MethodCallHandlerImpl.java

@@ -10,6 +10,7 @@ import static io.flutter.plugins.inapppurchase.Translator.fromBillingResult;
 import static io.flutter.plugins.inapppurchase.Translator.fromProductDetailsList;
 import static io.flutter.plugins.inapppurchase.Translator.fromPurchaseHistoryRecordList;
 import static io.flutter.plugins.inapppurchase.Translator.fromPurchasesList;
+import static io.flutter.plugins.inapppurchase.Translator.fromUserChoiceDetails;
 import static io.flutter.plugins.inapppurchase.Translator.toProductList;
 
 import android.app.Activity;
@@ -33,6 +34,7 @@ import com.android.billingclient.api.QueryProductDetailsParams;
 import com.android.billingclient.api.QueryProductDetailsParams.Product;
 import com.android.billingclient.api.QueryPurchaseHistoryParams;
 import com.android.billingclient.api.QueryPurchasesParams;
+import com.android.billingclient.api.UserChoiceBillingListener;
 import io.flutter.plugin.common.MethodCall;
 import io.flutter.plugin.common.MethodChannel;
 import java.util.ArrayList;
@@ -72,6 +74,8 @@ class MethodCallHandlerImpl
         "BillingClient#createAlternativeBillingOnlyReportingDetails()";
     static final String SHOW_ALTERNATIVE_BILLING_ONLY_INFORMATION_DIALOG =
         "BillingClient#showAlternativeBillingOnlyInformationDialog()";
+    static final String USER_SELECTED_ALTERNATIVE_BILLING =
+        "UserChoiceBillingListener#userSelectedAlternativeBilling(UserChoiceDetails)";
 
     private MethodNames() {}
   }
@@ -94,6 +98,7 @@ class MethodCallHandlerImpl
   static final class BillingChoiceMode {
     static final int PLAY_BILLING_ONLY = 0;
     static final int ALTERNATIVE_BILLING_ONLY = 1;
+    static final int USER_CHOICE_BILLING = 2;
   }
 
   // TODO(gmackall): Replace uses of deprecated ProrationMode enum values with new
@@ -507,9 +512,10 @@ class MethodCallHandlerImpl
   private void startConnection(
       final int handle, final MethodChannel.Result result, int billingChoiceMode) {
     if (billingClient == null) {
+      UserChoiceBillingListener listener = getUserChoiceBillingListener(billingChoiceMode);
       billingClient =
           billingClientFactory.createBillingClient(
-              applicationContext, methodChannel, billingChoiceMode);
+              applicationContext, methodChannel, billingChoiceMode, listener);
     }
 
     billingClient.startConnection(
@@ -537,6 +543,19 @@ class MethodCallHandlerImpl
         });
   }
 
+  @Nullable
+  private UserChoiceBillingListener getUserChoiceBillingListener(int billingChoiceMode) {
+    UserChoiceBillingListener listener = null;
+    if (billingChoiceMode == BillingChoiceMode.USER_CHOICE_BILLING) {
+      listener =
+          userChoiceDetails -> {
+            final Map<String, Object> arguments = fromUserChoiceDetails(userChoiceDetails);
+            methodChannel.invokeMethod(MethodNames.USER_SELECTED_ALTERNATIVE_BILLING, arguments);
+          };
+    }
+    return listener;
+  }
+
   private void acknowledgePurchase(String purchaseToken, final MethodChannel.Result result) {
     if (billingClientError(result)) {
       return;

packages/in_app_purchase/in_app_purchase_android/android/src/main/java/io/flutter/plugins/inapppurchase/Translator.java

@@ -14,6 +14,8 @@ import com.android.billingclient.api.ProductDetails;
 import com.android.billingclient.api.Purchase;
 import com.android.billingclient.api.PurchaseHistoryRecord;
 import com.android.billingclient.api.QueryProductDetailsParams;
+import com.android.billingclient.api.UserChoiceDetails;
+import com.android.billingclient.api.UserChoiceDetails.Product;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Currency;
@@ -233,6 +235,34 @@ import java.util.Map;
     return info;
   }
 
+  static HashMap<String, Object> fromUserChoiceDetails(UserChoiceDetails userChoiceDetails) {
+    HashMap<String, Object> info = new HashMap<>();
+    info.put("externalTransactionToken", userChoiceDetails.getExternalTransactionToken());
+    info.put("originalExternalTransactionId", userChoiceDetails.getOriginalExternalTransactionId());
+    info.put("products", fromProductsList(userChoiceDetails.getProducts()));
+    return info;
+  }
+
+  static List<HashMap<String, Object>> fromProductsList(List<Product> productsList) {
+    if (productsList.isEmpty()) {
+      return Collections.emptyList();
+    }
+    ArrayList<HashMap<String, Object>> output = new ArrayList<>();
+    for (Product product : productsList) {
+      output.add(fromProduct(product));
+    }
+    return output;
+  }
+
+  static HashMap<String, Object> fromProduct(Product product) {
+    HashMap<String, Object> info = new HashMap<>();
+    info.put("id", product.getId());
+    info.put("offerToken", product.getOfferToken());
+    info.put("productType", product.getType());
+
+    return info;
+  }
+
   /** Converter from {@link BillingResult} and {@link BillingConfig} to map. */
   static HashMap<String, Object> fromBillingConfig(
       BillingResult result, BillingConfig billingConfig) {

packages/in_app_purchase/in_app_purchase_android/android/src/test/java/io/flutter/plugins/inapppurchase/MethodCallHandlerTest.java

@@ -20,6 +20,7 @@ import static io.flutter.plugins.inapppurchase.MethodCallHandlerImpl.MethodNames
 import static io.flutter.plugins.inapppurchase.MethodCallHandlerImpl.MethodNames.QUERY_PURCHASE_HISTORY_ASYNC;
 import static io.flutter.plugins.inapppurchase.MethodCallHandlerImpl.MethodNames.SHOW_ALTERNATIVE_BILLING_ONLY_INFORMATION_DIALOG;
 import static io.flutter.plugins.inapppurchase.MethodCallHandlerImpl.MethodNames.START_CONNECTION;
+import static io.flutter.plugins.inapppurchase.MethodCallHandlerImpl.MethodNames.USER_SELECTED_ALTERNATIVE_BILLING;
 import static io.flutter.plugins.inapppurchase.PluginPurchaseListener.ON_PURCHASES_UPDATED;
 import static io.flutter.plugins.inapppurchase.Translator.fromAlternativeBillingOnlyReportingDetails;
 import static io.flutter.plugins.inapppurchase.Translator.fromBillingConfig;
@@ -27,6 +28,7 @@ import static io.flutter.plugins.inapppurchase.Translator.fromBillingResult;
 import static io.flutter.plugins.inapppurchase.Translator.fromProductDetailsList;
 import static io.flutter.plugins.inapppurchase.Translator.fromPurchaseHistoryRecordList;
 import static io.flutter.plugins.inapppurchase.Translator.fromPurchasesList;
+import static io.flutter.plugins.inapppurchase.Translator.fromUserChoiceDetails;
 import static java.util.Arrays.asList;
 import static java.util.Collections.singletonList;
 import static java.util.Collections.unmodifiableList;
@@ -73,6 +75,8 @@ import com.android.billingclient.api.PurchasesResponseListener;
 import com.android.billingclient.api.QueryProductDetailsParams;
 import com.android.billingclient.api.QueryPurchaseHistoryParams;
 import com.android.billingclient.api.QueryPurchasesParams;
+import com.android.billingclient.api.UserChoiceBillingListener;
+import com.android.billingclient.api.UserChoiceDetails;
 import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
 import io.flutter.plugin.common.MethodCall;
 import io.flutter.plugin.common.MethodChannel;
@@ -82,6 +86,7 @@ import io.flutter.plugins.inapppurchase.MethodCallHandlerImpl.MethodArgs;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -92,6 +97,7 @@ import org.junit.Test;
 import org.mockito.ArgumentCaptor;
 import org.mockito.Captor;
 import org.mockito.Mock;
+import org.mockito.Mockito;
 import org.mockito.MockitoAnnotations;
 import org.mockito.Spy;
 import org.mockito.stubbing.Answer;
@@ -107,15 +113,23 @@ public class MethodCallHandlerTest {
   @Mock ActivityPluginBinding mockActivityPluginBinding;
   @Captor ArgumentCaptor<HashMap<String, Object>> resultCaptor;
 
+  private final int DEFAULT_HANDLE = 1;
+
   @Before
   public void setUp() {
     MockitoAnnotations.openMocks(this);
     // Use the same client no matter if alternative billing is enabled or not.
     when(factory.createBillingClient(
-            context, mockMethodChannel, BillingChoiceMode.PLAY_BILLING_ONLY))
+            context, mockMethodChannel, BillingChoiceMode.PLAY_BILLING_ONLY, null))
         .thenReturn(mockBillingClient);
     when(factory.createBillingClient(
-            context, mockMethodChannel, BillingChoiceMode.ALTERNATIVE_BILLING_ONLY))
+            context, mockMethodChannel, BillingChoiceMode.ALTERNATIVE_BILLING_ONLY, null))
+        .thenReturn(mockBillingClient);
+    when(factory.createBillingClient(
+            any(Context.class),
+            any(MethodChannel.class),
+            eq(BillingChoiceMode.USER_CHOICE_BILLING),
+            any(UserChoiceBillingListener.class)))
         .thenReturn(mockBillingClient);
     methodChannelHandler = new MethodCallHandlerImpl(activity, context, mockMethodChannel, factory);
     when(mockActivityPluginBinding.getActivity()).thenReturn(activity);
@@ -164,7 +178,7 @@ public class MethodCallHandlerTest {
         mockStartConnection(BillingChoiceMode.PLAY_BILLING_ONLY);
     verify(result, never()).success(any());
     verify(factory, times(1))
-        .createBillingClient(context, mockMethodChannel, BillingChoiceMode.PLAY_BILLING_ONLY);
+        .createBillingClient(context, mockMethodChannel, BillingChoiceMode.PLAY_BILLING_ONLY, null);
 
     BillingResult billingResult =
         BillingResult.newBuilder()
@@ -183,7 +197,7 @@ public class MethodCallHandlerTest {
     verify(result, never()).success(any());
     verify(factory, times(1))
         .createBillingClient(
-            context, mockMethodChannel, BillingChoiceMode.ALTERNATIVE_BILLING_ONLY);
+            context, mockMethodChannel, BillingChoiceMode.ALTERNATIVE_BILLING_ONLY, null);
 
     BillingResult billingResult =
         BillingResult.newBuilder()
@@ -209,7 +223,7 @@ public class MethodCallHandlerTest {
     methodChannelHandler.onMethodCall(call, result);
     verify(result, never()).success(any());
     verify(factory, times(1))
-        .createBillingClient(context, mockMethodChannel, BillingChoiceMode.PLAY_BILLING_ONLY);
+        .createBillingClient(context, mockMethodChannel, BillingChoiceMode.PLAY_BILLING_ONLY, null);
 
     BillingResult billingResult =
         BillingResult.newBuilder()
@@ -221,6 +235,106 @@ public class MethodCallHandlerTest {
     verify(result, times(1)).success(fromBillingResult(billingResult));
   }
 
+  @Test
+  public void startConnectionUserChoiceBilling() {
+    ArgumentCaptor<BillingClientStateListener> captor =
+        mockStartConnection(BillingChoiceMode.USER_CHOICE_BILLING);
+    ArgumentCaptor<UserChoiceBillingListener> billingCaptor =
+        ArgumentCaptor.forClass(UserChoiceBillingListener.class);
+    verify(result, never()).success(any());
+    verify(factory, times(1))
+        .createBillingClient(
+            any(Context.class),
+            any(MethodChannel.class),
+            eq(BillingChoiceMode.USER_CHOICE_BILLING),
+            billingCaptor.capture());
+
+    BillingResult billingResult =
+        BillingResult.newBuilder()
+            .setResponseCode(100)
+            .setDebugMessage("dummy debug message")
+            .build();
+    captor.getValue().onBillingSetupFinished(billingResult);
+
+    verify(result, times(1)).success(fromBillingResult(billingResult));
+    UserChoiceDetails details = mock(UserChoiceDetails.class);
+    final String externalTransactionToken = "someLongTokenId1234";
+    final String originalTransactionId = "originalTransactionId123456";
+    when(details.getExternalTransactionToken()).thenReturn(externalTransactionToken);
+    when(details.getOriginalExternalTransactionId()).thenReturn(originalTransactionId);
+    when(details.getProducts()).thenReturn(Collections.emptyList());
+    billingCaptor.getValue().userSelectedAlternativeBilling(details);
+
+    verify(mockMethodChannel, times(1))
+        .invokeMethod(USER_SELECTED_ALTERNATIVE_BILLING, fromUserChoiceDetails(details));
+  }
+
+  @Test
+  public void userChoiceBillingOnSecondConnection() {
+    // First connection.
+    ArgumentCaptor<BillingClientStateListener> captor1 =
+        mockStartConnection(BillingChoiceMode.PLAY_BILLING_ONLY);
+    verify(result, never()).success(any());
+    verify(factory, times(1))
+        .createBillingClient(context, mockMethodChannel, BillingChoiceMode.PLAY_BILLING_ONLY, null);
+
+    BillingResult billingResult1 =
+        BillingResult.newBuilder()
+            .setResponseCode(100)
+            .setDebugMessage("dummy debug message")
+            .build();
+    final BillingClientStateListener stateListener = captor1.getValue();
+    stateListener.onBillingSetupFinished(billingResult1);
+    verify(result, times(1)).success(fromBillingResult(billingResult1));
+    Mockito.reset(result, mockMethodChannel, mockBillingClient);
+
+    // Disconnect
+    MethodCall disconnectCall = new MethodCall(END_CONNECTION, null);
+    methodChannelHandler.onMethodCall(disconnectCall, result);
+
+    // Verify that the client is disconnected and that the OnDisconnect callback has
+    // been triggered
+    verify(result, times(1)).success(any());
+    verify(mockBillingClient, times(1)).endConnection();
+    stateListener.onBillingServiceDisconnected();
+    Map<String, Integer> expectedInvocation = new HashMap<>();
+    expectedInvocation.put("handle", DEFAULT_HANDLE);
+    verify(mockMethodChannel, times(1)).invokeMethod(ON_DISCONNECT, expectedInvocation);
+    Mockito.reset(result, mockMethodChannel, mockBillingClient);
+
+    // Second connection.
+    ArgumentCaptor<BillingClientStateListener> captor2 =
+        mockStartConnection(BillingChoiceMode.USER_CHOICE_BILLING);
+    ArgumentCaptor<UserChoiceBillingListener> billingCaptor =
+        ArgumentCaptor.forClass(UserChoiceBillingListener.class);
+    verify(result, never()).success(any());
+    verify(factory, times(1))
+        .createBillingClient(
+            any(Context.class),
+            any(MethodChannel.class),
+            eq(BillingChoiceMode.USER_CHOICE_BILLING),
+            billingCaptor.capture());
+
+    BillingResult billingResult2 =
+        BillingResult.newBuilder()
+            .setResponseCode(100)
+            .setDebugMessage("dummy debug message")
+            .build();
+    captor2.getValue().onBillingSetupFinished(billingResult2);
+
+    verify(result, times(1)).success(fromBillingResult(billingResult2));
+    UserChoiceDetails details = mock(UserChoiceDetails.class);
+    final String externalTransactionToken = "someLongTokenId1234";
+    final String originalTransactionId = "originalTransactionId123456";
+    when(details.getExternalTransactionToken()).thenReturn(externalTransactionToken);
+    when(details.getOriginalExternalTransactionId()).thenReturn(originalTransactionId);
+    when(details.getProducts()).thenReturn(Collections.emptyList());
+    billingCaptor.getValue().userSelectedAlternativeBilling(details);
+
+    verify(mockMethodChannel, times(1))
+        .invokeMethod(USER_SELECTED_ALTERNATIVE_BILLING, fromUserChoiceDetails(details));
+  }
+
   @Test
   public void startConnection_multipleCalls() {
     Map<String, Object> arguments = new HashMap<>();
@@ -1071,7 +1185,7 @@ public class MethodCallHandlerTest {
    */
   private ArgumentCaptor<BillingClientStateListener> mockStartConnection(int billingChoiceMode) {
     Map<String, Object> arguments = new HashMap<>();
-    arguments.put(MethodArgs.HANDLE, 1);
+    arguments.put(MethodArgs.HANDLE, DEFAULT_HANDLE);
     arguments.put(MethodArgs.BILLING_CHOICE_MODE, billingChoiceMode);
     MethodCall call = new MethodCall(START_CONNECTION, arguments);
     ArgumentCaptor<BillingClientStateListener> captor =

packages/in_app_purchase/in_app_purchase_android/example/integration_test/in_app_purchase_test.dart

@@ -27,7 +27,8 @@ void main() {
     late final BillingClient billingClient;
 
     setUpAll(() {
-      billingClient = BillingClient((PurchasesResultWrapper _) {});
+      billingClient = BillingClient(
+          (PurchasesResultWrapper _) {}, (UserChoiceDetailsWrapper _) {});
     });
 
     testWidgets('BillingClient.acknowledgePurchase',

packages/in_app_purchase/in_app_purchase_android/example/lib/main.dart

@@ -44,6 +44,7 @@ class _MyAppState extends State<_MyApp> {
   final InAppPurchasePlatform _inAppPurchasePlatform =
       InAppPurchasePlatform.instance;
   late StreamSubscription<List<PurchaseDetails>> _subscription;
+  late StreamSubscription<GooglePlayUserChoiceDetails> _userChoiceDetailsStream;
   List<String> _notFoundIds = <String>[];
   List<ProductDetails> _products = <ProductDetails>[];
   List<PurchaseDetails> _purchases = <PurchaseDetails>[];
@@ -56,6 +57,7 @@ class _MyAppState extends State<_MyApp> {
   bool _purchasePending = false;
   bool _loading = true;
   String? _queryProductError;
+  final List<String> _userChoiceDetailsList = <String>[];
 
   @override
   void initState() {
@@ -70,6 +72,19 @@ class _MyAppState extends State<_MyApp> {
       // handle error here.
     });
     initStoreInfo();
+    final InAppPurchaseAndroidPlatformAddition addition =
+        InAppPurchasePlatformAddition.instance!
+            as InAppPurchaseAndroidPlatformAddition;
+    final Stream<GooglePlayUserChoiceDetails> userChoiceDetailsUpdated =
+        addition.userChoiceDetailsStream;
+    _userChoiceDetailsStream =
+        userChoiceDetailsUpdated.listen((GooglePlayUserChoiceDetails details) {
+      deliverUserChoiceDetails(details);
+    }, onDone: () {
+      _userChoiceDetailsStream.cancel();
+    }, onError: (Object error) {
+      // handle error here.
+    });
     super.initState();
   }
 
@@ -134,6 +149,8 @@ class _MyAppState extends State<_MyApp> {
   @override
   void dispose() {
     _subscription.cancel();
+    _userChoiceDetailsStream.cancel();
+    _userChoiceDetailsList.clear();
     super.dispose();
   }
 
@@ -149,6 +166,7 @@ class _MyAppState extends State<_MyApp> {
             _buildConsumableBox(),
             const _FeatureCard(),
             _buildFetchButtons(),
+            _buildUserChoiceDetailsDisplay(),
           ],
         ),
       );
@@ -326,6 +344,26 @@ class _MyAppState extends State<_MyApp> {
     );
   }
 
+  Card _buildUserChoiceDetailsDisplay() {
+    const ListTile header = ListTile(title: Text('UserChoiceDetails'));
+    final List<Widget> entries = <ListTile>[];
+    for (final String item in _userChoiceDetailsList) {
+      entries.add(ListTile(
+          title: Text(item,
+              style: TextStyle(color: ThemeData.light().colorScheme.primary)),
+          subtitle: Text(_countryCode)));
+    }
+    return Card(
+      child: Column(
+        children: <Widget>[
+          header,
+          const Divider(),
+          ...entries,
+        ],
+      ),
+    );
+  }
+
   Card _buildProductList() {
     if (_loading) {
       return const Card(
@@ -537,6 +575,15 @@ class _MyAppState extends State<_MyApp> {
     // handle invalid purchase here if  _verifyPurchase` failed.
   }
 
+  Future<void> deliverUserChoiceDetails(
+      GooglePlayUserChoiceDetails details) async {
+    final String detailDescription =
+        '${details.externalTransactionToken}, ${details.originalExternalTransactionId}, ${details.products.length}';
+    setState(() {
+      _userChoiceDetailsList.add(detailDescription);
+    });
+  }
+
   Future<void> _listenToPurchaseUpdated(
       List<PurchaseDetails> purchaseDetailsList) async {
     for (final PurchaseDetails purchaseDetails in purchaseDetailsList) {

packages/in_app_purchase/in_app_purchase_android/lib/billing_client_wrappers.dart

@@ -11,3 +11,4 @@ export 'src/billing_client_wrappers/product_details_wrapper.dart';
 export 'src/billing_client_wrappers/product_wrapper.dart';
 export 'src/billing_client_wrappers/purchase_wrapper.dart';
 export 'src/billing_client_wrappers/subscription_offer_details_wrapper.dart';
+export 'src/billing_client_wrappers/user_choice_details_wrapper.dart';

packages/in_app_purchase/in_app_purchase_android/lib/src/billing_client_wrappers/billing_client_manager.dart

@@ -8,6 +8,7 @@ import 'package:flutter/widgets.dart';
 
 import 'billing_client_wrapper.dart';
 import 'purchase_wrapper.dart';
+import 'user_choice_details_wrapper.dart';
 
 /// Abstraction of result of [BillingClient] operation that includes
 /// a [BillingResponse].
@@ -37,6 +38,13 @@ class BillingClientManager {
     _connect();
   }
 
+  /// Stream of `userSelectedAlternativeBilling` events from the [BillingClient].
+  ///
+  /// This is a broadcast stream, so it can be listened to multiple times.
+  /// A "done" event will be sent after [dispose] is called.
+  late final Stream<UserChoiceDetailsWrapper> userChoiceDetailsStream =
+      _userChoiceAlternativeBillingController.stream;
+
   /// Stream of `onPurchasesUpdated` events from the [BillingClient].
   ///
   /// This is a broadcast stream, so it can be listened to multiple times.
@@ -49,10 +57,14 @@ class BillingClientManager {
   /// In order to access the [BillingClient], use [runWithClient]
   /// and [runWithClientNonRetryable] methods.
   @visibleForTesting
-  late final BillingClient client = BillingClient(_onPurchasesUpdated);
+  late final BillingClient client =
+      BillingClient(_onPurchasesUpdated, onUserChoiceAlternativeBilling);
 
   final StreamController<PurchasesResultWrapper> _purchasesUpdatedController =
       StreamController<PurchasesResultWrapper>.broadcast();
+  final StreamController<UserChoiceDetailsWrapper>
+      _userChoiceAlternativeBillingController =
+      StreamController<UserChoiceDetailsWrapper>.broadcast();
 
   BillingChoiceMode _billingChoiceMode;
   bool _isConnecting = false;
@@ -113,12 +125,14 @@ class BillingClientManager {
   /// After calling [dispose]:
   /// - Further connection attempts will not be made.
   /// - [purchasesUpdatedStream] will be closed.
+  /// - [userChoiceDetailsStream] will be closed.
   /// - Calls to [runWithClient] and [runWithClientNonRetryable] will throw.
   void dispose() {
     _debugAssertNotDisposed();
     _isDisposed = true;
     client.endConnection();
     _purchasesUpdatedController.close();
+    _userChoiceAlternativeBillingController.close();
   }
 
   /// Ends connection to [BillingClient] and reconnects with [billingChoiceMode].
@@ -168,4 +182,14 @@ class BillingClientManager {
       'called dispose() on a BillingClientManager, it can no longer be used.',
     );
   }
+
+  /// Callback passed to [BillingClient] to use when customer chooses
+  /// alternative billing.
+  @visibleForTesting
+  void onUserChoiceAlternativeBilling(UserChoiceDetailsWrapper event) {
+    if (_isDisposed) {
+      return;
+    }
+    _userChoiceAlternativeBillingController.add(event);
+  }
 }

packages/in_app_purchase/in_app_purchase_android/lib/src/billing_client_wrappers/billing_client_wrapper.dart

@@ -18,6 +18,12 @@ part 'billing_client_wrapper.g.dart';
 @visibleForTesting
 const String kOnPurchasesUpdated =
     'PurchasesUpdatedListener#onPurchasesUpdated(BillingResult, List<Purchase>)';
+
+/// Method identifier for the userSelectedAlternativeBilling method channel method.
+@visibleForTesting
+const String kUserSelectedAlternativeBilling =
+    'UserChoiceBillingListener#userSelectedAlternativeBilling(UserChoiceDetails)';
+
 const String _kOnBillingServiceDisconnected =
     'BillingClientStateListener#onBillingServiceDisconnected()';
 
@@ -40,6 +46,10 @@ const String _kOnBillingServiceDisconnected =
 typedef PurchasesUpdatedListener = void Function(
     PurchasesResultWrapper purchasesResult);
 
+/// Wraps a [UserChoiceBillingListener](https://developer.android.com/reference/com/android/billingclient/api/UserChoiceBillingListener)
+typedef UserSelectedAlternativeBillingListener = void Function(
+    UserChoiceDetailsWrapper userChoiceDetailsWrapper);
+
 /// This class can be used directly instead of [InAppPurchaseConnection] to call
 /// Play-specific billing APIs.
 ///
@@ -60,11 +70,16 @@ typedef PurchasesUpdatedListener = void Function(
 /// transparently.
 class BillingClient {
   /// Creates a billing client.
-  BillingClient(PurchasesUpdatedListener onPurchasesUpdated) {
+  BillingClient(PurchasesUpdatedListener onPurchasesUpdated,
+      UserSelectedAlternativeBillingListener? alternativeBillingListener) {
     channel.setMethodCallHandler(callHandler);
     _callbacks[kOnPurchasesUpdated] = <PurchasesUpdatedListener>[
       onPurchasesUpdated
     ];
+    _callbacks[kUserSelectedAlternativeBilling] = alternativeBillingListener ==
+            null
+        ? <UserSelectedAlternativeBillingListener>[]
+        : <UserSelectedAlternativeBillingListener>[alternativeBillingListener];
   }
 
   // Occasionally methods in the native layer require a Dart callback to be
@@ -114,7 +129,8 @@ class BillingClient {
           BillingChoiceMode.playBillingOnly}) async {
     final List<Function> disconnectCallbacks =
         _callbacks[_kOnBillingServiceDisconnected] ??= <Function>[];
-    disconnectCallbacks.add(onBillingServiceDisconnected);
+    _callbacks[_kOnBillingServiceDisconnected]
+        ?.add(onBillingServiceDisconnected);
     return BillingResultWrapper.fromJson((await channel
             .invokeMapMethod<String, dynamic>(
                 'BillingClient#startConnection(BillingClientStateListener)',
@@ -412,6 +428,15 @@ class BillingClient {
             _callbacks[_kOnBillingServiceDisconnected]!
                 .cast<OnBillingServiceDisconnected>();
         onDisconnected[handle]();
+      case kUserSelectedAlternativeBilling:
+        if (_callbacks[kUserSelectedAlternativeBilling]!.isNotEmpty) {
+          final UserSelectedAlternativeBillingListener listener =
+              _callbacks[kUserSelectedAlternativeBilling]!.first
+                  as UserSelectedAlternativeBillingListener;
+          listener(UserChoiceDetailsWrapper.fromJson(
+              (call.arguments as Map<dynamic, dynamic>)
+                  .cast<String, dynamic>()));
+        }
     }
   }
 }
@@ -443,7 +468,7 @@ enum BillingResponse {
   @JsonValue(-2)
   featureNotSupported,
 
-  /// The play Store service is not connected now - potentially transient state.
+  /// The Play Store service is not connected now - potentially transient state.
   @JsonValue(-1)
   serviceDisconnected,
 
@@ -490,8 +515,8 @@ enum BillingResponse {
 
 /// Plugin concept to cover billing modes.
 ///
-/// [playBillingOnly] (google play billing only).
+/// [playBillingOnly] (google Play billing only).
-/// [alternativeBillingOnly] (app provided billing with reporting to play).
+/// [alternativeBillingOnly] (app provided billing with reporting to Play).
 @JsonEnum(alwaysCreate: true)
 enum BillingChoiceMode {
   // WARNING: Changes to this class need to be reflected in our generated code.
@@ -500,13 +525,17 @@ enum BillingChoiceMode {
   // Values must match what is used in
   // in_app_purchase_android/android/src/main/java/io/flutter/plugins/inapppurchase/MethodCallHandlerImpl.java
 
-  /// Billing through google play. Default state.
+  /// Billing through google Play. Default state.
   @JsonValue(0)
   playBillingOnly,
 
   /// Billing through app provided flow.
   @JsonValue(1)
   alternativeBillingOnly,
+
+  /// Users can choose Play billing or alternative billing.
+  @JsonValue(2)
+  userChoiceBilling,
 }
 
 /// Serializer for [BillingChoiceMode].

packages/in_app_purchase/in_app_purchase_android/lib/src/billing_client_wrappers/billing_client_wrapper.g.dart

@@ -25,6 +25,7 @@ const _$BillingResponseEnumMap = {
 const _$BillingChoiceModeEnumMap = {
   BillingChoiceMode.playBillingOnly: 0,
   BillingChoiceMode.alternativeBillingOnly: 1,
+  BillingChoiceMode.userChoiceBilling: 2,
 };
 
 const _$ProductTypeEnumMap = {

packages/in_app_purchase/in_app_purchase_android/lib/src/billing_client_wrappers/user_choice_details_wrapper.dart

@@ -0,0 +1,131 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/foundation.dart';
+import 'package:json_annotation/json_annotation.dart';
+
+import '../../billing_client_wrappers.dart';
+
+// WARNING: Changes to `@JsonSerializable` classes need to be reflected in the
+// below generated file. Run `flutter packages pub run build_runner watch` to
+// rebuild and watch for further changes.
+part 'user_choice_details_wrapper.g.dart';
+
+/// This wraps [`com.android.billingclient.api.UserChoiceDetails`](https://developer.android.com/reference/com/android/billingclient/api/UserChoiceDetails)
+// See https://docs.flutter.dev/data-and-backend/serialization/json#generating-code-for-nested-classes
+// for explination for why this uses explicitToJson.
+@JsonSerializable(createToJson: true, explicitToJson: true)
+@immutable
+class UserChoiceDetailsWrapper {
+  /// Creates a purchase wrapper with the given purchase details.
+  @visibleForTesting
+  const UserChoiceDetailsWrapper({
+    required this.originalExternalTransactionId,
+    required this.externalTransactionToken,
+    required this.products,
+  });
+
+  /// Factory for creating a [UserChoiceDetailsWrapper] from a [Map] with
+  /// the user choice details.
+  factory UserChoiceDetailsWrapper.fromJson(Map<String, dynamic> map) =>
+      _$UserChoiceDetailsWrapperFromJson(map);
+
+  /// Creates a JSON representation of this product.
+  Map<String, dynamic> toJson() => _$UserChoiceDetailsWrapperToJson(this);
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(other, this)) {
+      return true;
+    }
+    if (other.runtimeType != runtimeType) {
+      return false;
+    }
+    return other is UserChoiceDetailsWrapper &&
+        other.originalExternalTransactionId == originalExternalTransactionId &&
+        other.externalTransactionToken == externalTransactionToken &&
+        listEquals(other.products, products);
+  }
+
+  @override
+  int get hashCode => Object.hash(
+        originalExternalTransactionId,
+        externalTransactionToken,
+        products.hashCode,
+      );
+
+  /// Returns the external transaction Id of the originating subscription, if
+  /// the purchase is a subscription upgrade/downgrade.
+  @JsonKey(defaultValue: '')
+  final String originalExternalTransactionId;
+
+  /// Returns a token that represents the user's prospective purchase via
+  /// user choice alternative billing.
+  @JsonKey(defaultValue: '')
+  final String externalTransactionToken;
+
+  /// Returns a list of [UserChoiceDetailsProductWrapper] to be purchased in
+  /// the user choice alternative billing flow.
+  @JsonKey(defaultValue: <UserChoiceDetailsProductWrapper>[])
+  final List<UserChoiceDetailsProductWrapper> products;
+}
+
+/// Data structure representing a UserChoiceDetails product.
+///
+/// This wraps [`com.android.billingclient.api.UserChoiceDetails.Product`](https://developer.android.com/reference/com/android/billingclient/api/UserChoiceDetails.Product)
+//
+// See https://docs.flutter.dev/data-and-backend/serialization/json#generating-code-for-nested-classes
+// for explination for why this uses explicitToJson.
+@JsonSerializable(createToJson: true, explicitToJson: true)
+@ProductTypeConverter()
+@immutable
+class UserChoiceDetailsProductWrapper {
+  /// Creates a [UserChoiceDetailsProductWrapper] with the given record details.
+  @visibleForTesting
+  const UserChoiceDetailsProductWrapper({
+    required this.id,
+    required this.offerToken,
+    required this.productType,
+  });
+
+  /// Factory for creating a [UserChoiceDetailsProductWrapper] from a [Map] with the record details.
+  factory UserChoiceDetailsProductWrapper.fromJson(Map<String, dynamic> map) =>
+      _$UserChoiceDetailsProductWrapperFromJson(map);
+
+  /// Creates a JSON representation of this product.
+  Map<String, dynamic> toJson() =>
+      _$UserChoiceDetailsProductWrapperToJson(this);
+
+  /// Returns the id of the product being purchased.
+  @JsonKey(defaultValue: '')
+  final String id;
+
+  /// Returns the offer token that was passed in launchBillingFlow to purchase the product.
+  @JsonKey(defaultValue: '')
+  final String offerToken;
+
+  /// Returns the [ProductType] of the product being purchased.
+  final ProductType productType;
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(other, this)) {
+      return true;
+    }
+    if (other.runtimeType != runtimeType) {
+      return false;
+    }
+    return other is UserChoiceDetailsProductWrapper &&
+        other.id == id &&
+        other.offerToken == offerToken &&
+        other.productType == productType;
+  }
+
+  @override
+  int get hashCode => Object.hash(
+        id,
+        offerToken,
+        productType,
+      );
+}

packages/in_app_purchase/in_app_purchase_android/lib/src/billing_client_wrappers/user_choice_details_wrapper.g.dart

@@ -0,0 +1,45 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'user_choice_details_wrapper.dart';
+
+// **************************************************************************
+// JsonSerializableGenerator
+// **************************************************************************
+
+UserChoiceDetailsWrapper _$UserChoiceDetailsWrapperFromJson(Map json) =>
+    UserChoiceDetailsWrapper(
+      originalExternalTransactionId:
+          json['originalExternalTransactionId'] as String? ?? '',
+      externalTransactionToken:
+          json['externalTransactionToken'] as String? ?? '',
+      products: (json['products'] as List<dynamic>?)
+              ?.map((e) => UserChoiceDetailsProductWrapper.fromJson(
+                  Map<String, dynamic>.from(e as Map)))
+              .toList() ??
+          [],
+    );
+
+Map<String, dynamic> _$UserChoiceDetailsWrapperToJson(
+        UserChoiceDetailsWrapper instance) =>
+    <String, dynamic>{
+      'originalExternalTransactionId': instance.originalExternalTransactionId,
+      'externalTransactionToken': instance.externalTransactionToken,
+      'products': instance.products.map((e) => e.toJson()).toList(),
+    };
+
+UserChoiceDetailsProductWrapper _$UserChoiceDetailsProductWrapperFromJson(
+        Map json) =>
+    UserChoiceDetailsProductWrapper(
+      id: json['id'] as String? ?? '',
+      offerToken: json['offerToken'] as String? ?? '',
+      productType:
+          const ProductTypeConverter().fromJson(json['productType'] as String?),
+    );
+
+Map<String, dynamic> _$UserChoiceDetailsProductWrapperToJson(
+        UserChoiceDetailsProductWrapper instance) =>
+    <String, dynamic>{
+      'id': instance.id,
+      'offerToken': instance.offerToken,
+      'productType': const ProductTypeConverter().toJson(instance.productType),
+    };

packages/in_app_purchase/in_app_purchase_android/lib/src/in_app_purchase_android_platform_addition.dart

@@ -2,19 +2,34 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
+
 import 'package:flutter/services.dart';
 import 'package:in_app_purchase_platform_interface/in_app_purchase_platform_interface.dart';
 
 import '../billing_client_wrappers.dart';
 import '../in_app_purchase_android.dart';
 import 'billing_client_wrappers/billing_config_wrapper.dart';
+import 'types/translator.dart';
 
 /// Contains InApp Purchase features that are only available on PlayStore.
 class InAppPurchaseAndroidPlatformAddition
     extends InAppPurchasePlatformAddition {
   /// Creates a [InAppPurchaseAndroidPlatformAddition] which uses the supplied
   /// `BillingClientManager` to provide Android specific features.
-  InAppPurchaseAndroidPlatformAddition(this._billingClientManager);
+  InAppPurchaseAndroidPlatformAddition(this._billingClientManager) {
+    _billingClientManager.userChoiceDetailsStream
+        .map(Translator.convertToUserChoiceDetails)
+        .listen(_userChoiceDetailsStreamController.add);
+  }
+
+  final StreamController<GooglePlayUserChoiceDetails>
+      _userChoiceDetailsStreamController =
+      StreamController<GooglePlayUserChoiceDetails>.broadcast();
+
+  /// [GooglePlayUserChoiceDetails] emits each time user selects alternative billing.
+  late final Stream<GooglePlayUserChoiceDetails> userChoiceDetailsStream =
+      _userChoiceDetailsStreamController.stream;
 
   /// Whether pending purchase is enabled.
   ///

packages/in_app_purchase/in_app_purchase_android/lib/src/types/google_play_user_choice_details.dart

@@ -0,0 +1,101 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/foundation.dart';
+
+/// Data structure representing a UserChoiceDetails.
+///
+/// This wraps [`com.android.billingclient.api.UserChoiceDetails`](https://developer.android.com/reference/com/android/billingclient/api/UserChoiceDetails)
+@immutable
+class GooglePlayUserChoiceDetails {
+  /// Creates a new Google Play specific user choice billing details object with
+  /// the provided details.
+  const GooglePlayUserChoiceDetails({
+    required this.originalExternalTransactionId,
+    required this.externalTransactionToken,
+    required this.products,
+  });
+
+  /// Returns the external transaction Id of the originating subscription, if
+  /// the purchase is a subscription upgrade/downgrade.
+  final String originalExternalTransactionId;
+
+  /// Returns a token that represents the user's prospective purchase via
+  /// user choice alternative billing.
+  final String externalTransactionToken;
+
+  /// Returns a list of [GooglePlayUserChoiceDetailsProduct] to be purchased in
+  /// the user choice alternative billing flow.
+  final List<GooglePlayUserChoiceDetailsProduct> products;
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(other, this)) {
+      return true;
+    }
+    if (other.runtimeType != runtimeType) {
+      return false;
+    }
+    return other is GooglePlayUserChoiceDetails &&
+        other.originalExternalTransactionId == originalExternalTransactionId &&
+        other.externalTransactionToken == externalTransactionToken &&
+        listEquals(other.products, products);
+  }
+
+  @override
+  int get hashCode => Object.hash(
+        originalExternalTransactionId,
+        externalTransactionToken,
+        products.hashCode,
+      );
+}
+
+/// Data structure representing a UserChoiceDetails product.
+///
+/// This wraps [`com.android.billingclient.api.UserChoiceDetails.Product`](https://developer.android.com/reference/com/android/billingclient/api/UserChoiceDetails.Product)
+@immutable
+class GooglePlayUserChoiceDetailsProduct {
+  /// Creates UserChoiceDetailsProduct.
+  const GooglePlayUserChoiceDetailsProduct(
+      {required this.id, required this.offerToken, required this.productType});
+
+  /// Returns the id of the product being purchased.
+  final String id;
+
+  /// Returns the offer token that was passed in launchBillingFlow to purchase the product.
+  final String offerToken;
+
+  /// Returns the [GooglePlayProductType] of the product being purchased.
+  final GooglePlayProductType productType;
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(other, this)) {
+      return true;
+    }
+    if (other.runtimeType != runtimeType) {
+      return false;
+    }
+    return other is GooglePlayUserChoiceDetailsProduct &&
+        other.id == id &&
+        other.offerToken == offerToken &&
+        other.productType == productType;
+  }
+
+  @override
+  int get hashCode => Object.hash(
+        id,
+        offerToken,
+        productType,
+      );
+}
+
+/// This wraps [`com.android.billingclient.api.BillingClient.ProductType`](https://developer.android.com/reference/com/android/billingclient/api/BillingClient.ProductType)
+enum GooglePlayProductType {
+  /// A Product type for Android apps in-app products.
+  inapp,
+
+  /// A Product type for Android apps subscriptions.
+  subs
+}

packages/in_app_purchase/in_app_purchase_android/lib/src/types/translator.dart

@@ -0,0 +1,47 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/foundation.dart';
+
+import '../../billing_client_wrappers.dart';
+import 'google_play_user_choice_details.dart';
+
+/// Class used to convert cross process object into api expose objects.
+class Translator {
+  Translator._();
+
+  /// Converts from [UserChoiceDetailsWrapper] to [GooglePlayUserChoiceDetails].
+  static GooglePlayUserChoiceDetails convertToUserChoiceDetails(
+      UserChoiceDetailsWrapper detailsWrapper) {
+    return GooglePlayUserChoiceDetails(
+        originalExternalTransactionId:
+            detailsWrapper.originalExternalTransactionId,
+        externalTransactionToken: detailsWrapper.externalTransactionToken,
+        products: detailsWrapper.products
+            .map((UserChoiceDetailsProductWrapper e) =>
+                convertToUserChoiceDetailsProduct(e))
+            .toList());
+  }
+
+  /// Converts from [UserChoiceDetailsProductWrapper] to [GooglePlayUserChoiceDetailsProduct].
+  @visibleForTesting
+  static GooglePlayUserChoiceDetailsProduct convertToUserChoiceDetailsProduct(
+      UserChoiceDetailsProductWrapper productWrapper) {
+    return GooglePlayUserChoiceDetailsProduct(
+        id: productWrapper.id,
+        offerToken: productWrapper.offerToken,
+        productType: convertToPlayProductType(productWrapper.productType));
+  }
+
+  /// Coverts from [ProductType] to [GooglePlayProductType].
+  @visibleForTesting
+  static GooglePlayProductType convertToPlayProductType(ProductType type) {
+    switch (type) {
+      case ProductType.inapp:
+        return GooglePlayProductType.inapp;
+      case ProductType.subs:
+        return GooglePlayProductType.subs;
+    }
+  }
+}

packages/in_app_purchase/in_app_purchase_android/lib/src/types/types.dart

@@ -6,4 +6,5 @@ export 'change_subscription_param.dart';
 export 'google_play_product_details.dart';
 export 'google_play_purchase_details.dart';
 export 'google_play_purchase_param.dart';
+export 'google_play_user_choice_details.dart';
 export 'query_purchase_details_response.dart';

packages/in_app_purchase/in_app_purchase_android/pubspec.yaml

@@ -2,7 +2,7 @@ name: in_app_purchase_android
 description: An implementation for the Android platform of the Flutter `in_app_purchase` plugin. This uses the Android BillingClient APIs.
 repository: https://github.com/flutter/packages/tree/main/packages/in_app_purchase/in_app_purchase_android
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+in_app_purchase%22
-version: 0.3.1
+version: 0.3.2
 
 environment:
   sdk: ^3.1.0

packages/in_app_purchase/in_app_purchase_android/test/billing_client_wrappers/billing_client_manager_test.dart

@@ -138,5 +138,32 @@ void main() {
       expect(stubPlatform.countPreviousCalls(startConnectionCall), equals(1));
       expect(stubPlatform.countPreviousCalls(endConnectionCall), equals(1));
     });
+
+    test(
+        'Emits UserChoiceDetailsWrapper when onUserChoiceAlternativeBilling is called',
+        () async {
+      connectedCompleter.complete();
+      // Ensures all asynchronous connected code finishes.
+      await manager.runWithClientNonRetryable((_) async {});
+
+      const UserChoiceDetailsWrapper expected = UserChoiceDetailsWrapper(
+        originalExternalTransactionId: 'TransactionId',
+        externalTransactionToken: 'TransactionToken',
+        products: <UserChoiceDetailsProductWrapper>[
+          UserChoiceDetailsProductWrapper(
+              id: 'id1',
+              offerToken: 'offerToken1',
+              productType: ProductType.inapp),
+          UserChoiceDetailsProductWrapper(
+              id: 'id2',
+              offerToken: 'offerToken2',
+              productType: ProductType.inapp),
+        ],
+      );
+      final Future<UserChoiceDetailsWrapper> detailsFuture =
+          manager.userChoiceDetailsStream.first;
+      manager.onUserChoiceAlternativeBilling(expected);
+      expect(await detailsFuture, expected);
+    });
   });
 }

packages/in_app_purchase/in_app_purchase_android/test/billing_client_wrappers/billing_client_wrapper_test.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
+
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:in_app_purchase_android/billing_client_wrappers.dart';
@@ -37,7 +39,8 @@ void main() {
       .setMockMethodCallHandler(channel, stubPlatform.fakeMethodCallHandler));
 
   setUp(() {
-    billingClient = BillingClient((PurchasesResultWrapper _) {});
+    billingClient = BillingClient(
+        (PurchasesResultWrapper _) {}, (UserChoiceDetailsWrapper _) {});
     stubPlatform.reset();
   });
 
@@ -114,7 +117,7 @@ void main() {
           }));
     });
 
-    test('passes billingChoiceMode when set', () async {
+    test('passes billingChoiceMode alternativeBillingOnly when set', () async {
       const String debugMessage = 'dummy message';
       const BillingResponse responseCode = BillingResponse.developerError;
       stubPlatform.addResponse(
@@ -136,6 +139,91 @@ void main() {
           }));
     });
 
+    test('passes billingChoiceMode userChoiceBilling when set', () async {
+      const String debugMessage = 'dummy message';
+      const BillingResponse responseCode = BillingResponse.ok;
+      stubPlatform.addResponse(
+        name: methodName,
+        value: <String, dynamic>{
+          'responseCode': const BillingResponseConverter().toJson(responseCode),
+          'debugMessage': debugMessage,
+        },
+      );
+      final Completer<UserChoiceDetailsWrapper> completer =
+          Completer<UserChoiceDetailsWrapper>();
+
+      billingClient = BillingClient((PurchasesResultWrapper _) {},
+          (UserChoiceDetailsWrapper details) => completer.complete(details));
+      stubPlatform.reset();
+      await billingClient.startConnection(
+          onBillingServiceDisconnected: () {},
+          billingChoiceMode: BillingChoiceMode.userChoiceBilling);
+      final MethodCall call = stubPlatform.previousCallMatching(methodName);
+      expect(
+          call.arguments,
+          equals(<dynamic, dynamic>{
+            'handle': 0,
+            'billingChoiceMode': 2,
+          }));
+      const UserChoiceDetailsWrapper expected = UserChoiceDetailsWrapper(
+        originalExternalTransactionId: 'TransactionId',
+        externalTransactionToken: 'TransactionToken',
+        products: <UserChoiceDetailsProductWrapper>[
+          UserChoiceDetailsProductWrapper(
+              id: 'id1',
+              offerToken: 'offerToken1',
+              productType: ProductType.inapp),
+          UserChoiceDetailsProductWrapper(
+              id: 'id2',
+              offerToken: 'offerToken2',
+              productType: ProductType.inapp),
+        ],
+      );
+      await billingClient.callHandler(
+          MethodCall(kUserSelectedAlternativeBilling, expected.toJson()));
+      expect(completer.isCompleted, isTrue);
+      expect(await completer.future, expected);
+    });
+
+    test('UserChoiceDetailsWrapper searilization check', () async {
+      // Test ensures that changes to UserChoiceDetailsWrapper#toJson are
+      // compatible with code in Translator.java.
+      const String transactionIdKey = 'originalExternalTransactionId';
+      const String transactionTokenKey = 'externalTransactionToken';
+      const String productsKey = 'products';
+      const String productIdKey = 'id';
+      const String productOfferTokenKey = 'offerToken';
+      const String productTypeKey = 'productType';
+
+      const UserChoiceDetailsProductWrapper expectedProduct1 =
+          UserChoiceDetailsProductWrapper(
+              id: 'id1',
+              offerToken: 'offerToken1',
+              productType: ProductType.inapp);
+      const UserChoiceDetailsProductWrapper expectedProduct2 =
+          UserChoiceDetailsProductWrapper(
+              id: 'id2',
+              offerToken: 'offerToken2',
+              productType: ProductType.inapp);
+      const UserChoiceDetailsWrapper expected = UserChoiceDetailsWrapper(
+        originalExternalTransactionId: 'TransactionId',
+        externalTransactionToken: 'TransactionToken',
+        products: <UserChoiceDetailsProductWrapper>[
+          expectedProduct1,
+          expectedProduct2,
+        ],
+      );
+      final Map<String, dynamic> detailsJson = expected.toJson();
+      expect(detailsJson.keys, contains(transactionIdKey));
+      expect(detailsJson.keys, contains(transactionTokenKey));
+      expect(detailsJson.keys, contains(productsKey));
+
+      final Map<String, dynamic> productJson = expectedProduct1.toJson();
+      expect(productJson, contains(productIdKey));
+      expect(productJson, contains(productOfferTokenKey));
+      expect(productJson, contains(productTypeKey));
+    });
+
     test('handles method channel returning null', () async {
       stubPlatform.addResponse(
         name: methodName,

packages/in_app_purchase/in_app_purchase_android/test/in_app_purchase_android_platform_addition_test.dart

@@ -9,6 +9,7 @@ import 'package:in_app_purchase_android/billing_client_wrappers.dart';
 import 'package:in_app_purchase_android/in_app_purchase_android.dart';
 import 'package:in_app_purchase_android/src/billing_client_wrappers/billing_config_wrapper.dart';
 import 'package:in_app_purchase_android/src/channel.dart';
+import 'package:in_app_purchase_android/src/types/translator.dart';
 
 import 'billing_client_wrappers/billing_client_wrapper_test.dart';
 import 'billing_client_wrappers/purchase_wrapper_test.dart';
@@ -281,4 +282,28 @@ void main() {
       expect(arguments['feature'], equals('subscriptions'));
     });
   });
+
+  group('userChoiceDetails', () {
+    test('called', () async {
+      final Future<GooglePlayUserChoiceDetails> futureDetails =
+          iapAndroidPlatformAddition.userChoiceDetailsStream.first;
+      const UserChoiceDetailsWrapper expected = UserChoiceDetailsWrapper(
+        originalExternalTransactionId: 'TransactionId',
+        externalTransactionToken: 'TransactionToken',
+        products: <UserChoiceDetailsProductWrapper>[
+          UserChoiceDetailsProductWrapper(
+              id: 'id1',
+              offerToken: 'offerToken1',
+              productType: ProductType.inapp),
+          UserChoiceDetailsProductWrapper(
+              id: 'id2',
+              offerToken: 'offerToken2',
+              productType: ProductType.inapp),
+        ],
+      );
+      manager.onUserChoiceAlternativeBilling(expected);
+      expect(
+          await futureDetails, Translator.convertToUserChoiceDetails(expected));
+    });
+  });
 }

packages/in_app_purchase/in_app_purchase_android/test/types/translator_test.dart

@@ -0,0 +1,71 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:in_app_purchase_android/billing_client_wrappers.dart';
+import 'package:in_app_purchase_android/src/types/google_play_user_choice_details.dart';
+import 'package:in_app_purchase_android/src/types/translator.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('Translator ', () {
+    test('convertToPlayProductType', () {
+      expect(Translator.convertToPlayProductType(ProductType.inapp),
+          GooglePlayProductType.inapp);
+      expect(Translator.convertToPlayProductType(ProductType.subs),
+          GooglePlayProductType.subs);
+      expect(GooglePlayProductType.values.length, ProductType.values.length);
+    });
+
+    test('convertToUserChoiceDetailsProduct', () {
+      const GooglePlayUserChoiceDetailsProduct expected =
+          GooglePlayUserChoiceDetailsProduct(
+              id: 'id',
+              offerToken: 'offerToken',
+              productType: GooglePlayProductType.inapp);
+      expect(
+          Translator.convertToUserChoiceDetailsProduct(
+              UserChoiceDetailsProductWrapper(
+                  id: expected.id,
+                  offerToken: expected.offerToken,
+                  productType: ProductType.inapp)),
+          expected);
+    });
+    test('convertToUserChoiceDetailsProduct', () {
+      const GooglePlayUserChoiceDetailsProduct expectedProduct1 =
+          GooglePlayUserChoiceDetailsProduct(
+              id: 'id1',
+              offerToken: 'offerToken1',
+              productType: GooglePlayProductType.inapp);
+      const GooglePlayUserChoiceDetailsProduct expectedProduct2 =
+          GooglePlayUserChoiceDetailsProduct(
+              id: 'id2',
+              offerToken: 'offerToken2',
+              productType: GooglePlayProductType.subs);
+      const GooglePlayUserChoiceDetails expected = GooglePlayUserChoiceDetails(
+          originalExternalTransactionId: 'originalExternalTransactionId',
+          externalTransactionToken: 'externalTransactionToken',
+          products: <GooglePlayUserChoiceDetailsProduct>[
+            expectedProduct1,
+            expectedProduct2
+          ]);
+
+      expect(
+          Translator.convertToUserChoiceDetails(UserChoiceDetailsWrapper(
+              originalExternalTransactionId:
+                  expected.originalExternalTransactionId,
+              externalTransactionToken: expected.externalTransactionToken,
+              products: <UserChoiceDetailsProductWrapper>[
+                UserChoiceDetailsProductWrapper(
+                    id: expectedProduct1.id,
+                    offerToken: expectedProduct1.offerToken,
+                    productType: ProductType.inapp),
+                UserChoiceDetailsProductWrapper(
+                    id: expectedProduct2.id,
+                    offerToken: expectedProduct2.offerToken,
+                    productType: ProductType.subs),
+              ])),
+          expected);
+    });
+  });
+}