[in_app_purchase] Add alternative billing apis for android (flutter#6056)

- Update the emulator versions and expose cipd. (flutter#6025
- Enable alternitive billing only available check, add test and code to handle service unavilable in getBillingConfig
- Enable alternative billing only during client creation and tests covering fallback path
- ShowAlternativeBillingDialog android native method added
- Add tests for null activity behavior
- Remove not needed lines of code
- Add showAlternativeBillingOnlyInformationDialog and isAlternativeBillingOnlyAvailable to android platform addition and billing client wrapper.
- test showAlternativeBillingOnlyInformationDialog and isAlternativeBillingOnlyAvailable in platfrom addition and billing_client

Fixes flutter/issues/142618

Still left TODO: 
* [x] incorporate new apis into example app 
* [x] expose alternative billing only [dart api](https://github.com/flutter/packages/pull/6056/files/d4c445422f2cd3f0627f575d85b59b559e0e9f69#r1480455450)
* [x] Expose alternative billing reporting details
* [ ] Configure end to end working example with playstore

Author: reidbaker

packages/in_app_purchase/in_app_purchase_android/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.3.1
+
+* Adds alternative-billing-only APIs to InAppPurchaseAndroidPlatformAddition.
+
 ## 0.3.0+18
 
 * Adds new getCountryCode() method to InAppPurchaseAndroidPlatformAddition to get a customer's country code.

packages/in_app_purchase/in_app_purchase_android/android/build.gradle

@@ -66,6 +66,6 @@ dependencies {
     testImplementation 'junit:junit:4.13.2'
     testImplementation 'org.json:json:20231013'
     testImplementation 'org.mockito:mockito-core:5.4.0'
-    androidTestImplementation 'androidx.test:runner:1.4.0'
+    androidTestImplementation 'androidx.test:runner:1.5.2'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
 }

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

@@ -17,7 +17,10 @@ interface BillingClientFactory {
    *
    * @param context The context used to create the {@link BillingClient}.
    * @param channel The method channel used to create the {@link BillingClient}.
+   * @param billingChoiceMode Enables the ability to offer alternative billing or Google Play
+   *     billing.
    * @return The {@link BillingClient} object that is created.
    */
-  BillingClient createBillingClient(@NonNull Context context, @NonNull MethodChannel channel);
+  BillingClient createBillingClient(
+      @NonNull Context context, @NonNull MethodChannel channel, int billingChoiceMode);
 }

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

@@ -8,15 +8,19 @@
 import androidx.annotation.NonNull;
 import com.android.billingclient.api.BillingClient;
 import io.flutter.plugin.common.MethodChannel;
+import io.flutter.plugins.inapppurchase.MethodCallHandlerImpl.BillingChoiceMode;
 
 /** The implementation for {@link BillingClientFactory} for the plugin. */
 final class BillingClientFactoryImpl implements BillingClientFactory {
 
   @Override
   public BillingClient createBillingClient(
-      @NonNull Context context, @NonNull MethodChannel channel) {
+      @NonNull Context context, @NonNull MethodChannel channel, int billingChoiceMode) {
     BillingClient.Builder builder = BillingClient.newBuilder(context).enablePendingPurchases();
-
+    if (billingChoiceMode == BillingChoiceMode.ALTERNATIVE_BILLING_ONLY) {
+      // https://developer.android.com/google/play/billing/alternative/alternative-billing-without-user-choice-in-app
+      builder.enableAlternativeBillingOnly();
+    }
     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

@@ -4,6 +4,7 @@
 
 package io.flutter.plugins.inapppurchase;
 
+import static io.flutter.plugins.inapppurchase.Translator.fromAlternativeBillingOnlyReportingDetails;
 import static io.flutter.plugins.inapppurchase.Translator.fromBillingConfig;
 import static io.flutter.plugins.inapppurchase.Translator.fromBillingResult;
 import static io.flutter.plugins.inapppurchase.Translator.fromProductDetailsList;
@@ -65,10 +66,36 @@ static final class MethodNames {
     static final String IS_FEATURE_SUPPORTED = "BillingClient#isFeatureSupported(String)";
     static final String GET_CONNECTION_STATE = "BillingClient#getConnectionState()";
     static final String GET_BILLING_CONFIG = "BillingClient#getBillingConfig()";
+    static final String IS_ALTERNATIVE_BILLING_ONLY_AVAILABLE =
+        "BillingClient#isAlternativeBillingOnlyAvailable()";
+    static final String CREATE_ALTERNATIVE_BILLING_ONLY_REPORTING_DETAILS =
+        "BillingClient#createAlternativeBillingOnlyReportingDetails()";
+    static final String SHOW_ALTERNATIVE_BILLING_ONLY_INFORMATION_DIALOG =
+        "BillingClient#showAlternativeBillingOnlyInformationDialog()";
 
     private MethodNames() {}
   }
 
+  @VisibleForTesting
+  static final class MethodArgs {
+
+    // Key for an int argument passed into startConnection
+    static final String HANDLE = "handle";
+    // Key for a boolean argument passed into startConnection.
+    static final String BILLING_CHOICE_MODE = "billingChoiceMode";
+
+    private MethodArgs() {}
+  }
+
+  /**
+   * Values here must match values used in
+   * in_app_purchase_android/lib/src/billing_client_wrappers/billing_client_wrapper.dart
+   */
+  static final class BillingChoiceMode {
+    static final int PLAY_BILLING_ONLY = 0;
+    static final int ALTERNATIVE_BILLING_ONLY = 1;
+  }
+
   // TODO(gmackall): Replace uses of deprecated ProrationMode enum values with new
   // ReplacementMode enum values.
   // https://github.com/flutter/flutter/issues/128957.
@@ -80,6 +107,7 @@ private MethodNames() {}
   private static final String TAG = "InAppPurchasePlugin";
   private static final String LOAD_PRODUCT_DOC_URL =
       "https://github.com/flutter/packages/blob/main/packages/in_app_purchase/in_app_purchase/README.md#loading-products-for-sale";
+  @VisibleForTesting static final String ACTIVITY_UNAVAILABLE = "ACTIVITY_UNAVAILABLE";
 
   @Nullable private BillingClient billingClient;
   private final BillingClientFactory billingClientFactory;
@@ -147,7 +175,12 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull MethodChannel.Result
         isReady(result);
         break;
       case MethodNames.START_CONNECTION:
-        startConnection((int) call.argument("handle"), result);
+        final int handle = (int) call.argument(MethodArgs.HANDLE);
+        int billingChoiceMode = BillingChoiceMode.PLAY_BILLING_ONLY;
+        if (call.hasArgument(MethodArgs.BILLING_CHOICE_MODE)) {
+          billingChoiceMode = call.argument(MethodArgs.BILLING_CHOICE_MODE);
+        }
+        startConnection(handle, result, billingChoiceMode);
         break;
       case MethodNames.END_CONNECTION:
         endConnection(result);
@@ -190,12 +223,61 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull MethodChannel.Result
       case MethodNames.GET_BILLING_CONFIG:
         getBillingConfig(result);
         break;
+      case MethodNames.IS_ALTERNATIVE_BILLING_ONLY_AVAILABLE:
+        isAlternativeBillingOnlyAvailable(result);
+        break;
+      case MethodNames.CREATE_ALTERNATIVE_BILLING_ONLY_REPORTING_DETAILS:
+        createAlternativeBillingOnlyReportingDetails(result);
+        break;
+      case MethodNames.SHOW_ALTERNATIVE_BILLING_ONLY_INFORMATION_DIALOG:
+        showAlternativeBillingOnlyInformationDialog(result);
+        break;
       default:
         result.notImplemented();
     }
   }
 
+  private void showAlternativeBillingOnlyInformationDialog(final MethodChannel.Result result) {
+    if (billingClientError(result)) {
+      return;
+    }
+    if (activity == null) {
+      result.error(ACTIVITY_UNAVAILABLE, "Not attempting to show dialog", null);
+      return;
+    }
+    billingClient.showAlternativeBillingOnlyInformationDialog(
+        activity,
+        billingResult -> {
+          result.success(fromBillingResult(billingResult));
+        });
+  }
+
+  private void createAlternativeBillingOnlyReportingDetails(final MethodChannel.Result result) {
+    if (billingClientError(result)) {
+      return;
+    }
+    billingClient.createAlternativeBillingOnlyReportingDetailsAsync(
+        ((billingResult, alternativeBillingOnlyReportingDetails) -> {
+          result.success(
+              fromAlternativeBillingOnlyReportingDetails(
+                  billingResult, alternativeBillingOnlyReportingDetails));
+        }));
+  }
+
+  private void isAlternativeBillingOnlyAvailable(final MethodChannel.Result result) {
+    if (billingClientError(result)) {
+      return;
+    }
+    billingClient.isAlternativeBillingOnlyAvailableAsync(
+        billingResult -> {
+          result.success(fromBillingResult(billingResult));
+        });
+  }
+
   private void getBillingConfig(final MethodChannel.Result result) {
+    if (billingClientError(result)) {
+      return;
+    }
     billingClient.getBillingConfigAsync(
         GetBillingConfigParams.newBuilder().build(),
         (billingResult, billingConfig) -> {
@@ -313,7 +395,7 @@ private void launchBillingFlow(
 
     if (activity == null) {
       result.error(
-          "ACTIVITY_UNAVAILABLE",
+          ACTIVITY_UNAVAILABLE,
           "Details for product "
               + product
               + " are not available. This method must be run with the app in foreground.",
@@ -422,9 +504,12 @@ private void getConnectionState(final MethodChannel.Result result) {
     result.success(serialized);
   }
 
-  private void startConnection(final int handle, final MethodChannel.Result result) {
+  private void startConnection(
+      final int handle, final MethodChannel.Result result, int billingChoiceMode) {
     if (billingClient == null) {
-      billingClient = billingClientFactory.createBillingClient(applicationContext, methodChannel);
+      billingClient =
+          billingClientFactory.createBillingClient(
+              applicationContext, methodChannel, billingChoiceMode);
     }
 
     billingClient.startConnection(

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

@@ -7,6 +7,7 @@
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import com.android.billingclient.api.AccountIdentifiers;
+import com.android.billingclient.api.AlternativeBillingOnlyReportingDetails;
 import com.android.billingclient.api.BillingConfig;
 import com.android.billingclient.api.BillingResult;
 import com.android.billingclient.api.ProductDetails;
@@ -240,6 +241,18 @@ static HashMap<String, Object> fromBillingConfig(
     return info;
   }
 
+  /**
+   * Converter from {@link BillingResult} and {@link AlternativeBillingOnlyReportingDetails} to map.
+   */
+  static HashMap<String, Object> fromAlternativeBillingOnlyReportingDetails(
+      BillingResult result, AlternativeBillingOnlyReportingDetails details) {
+    HashMap<String, Object> info = fromBillingResult(result);
+    if (details != null) {
+      info.put("externalTransactionToken", details.getExternalTransactionToken());
+    }
+    return info;
+  }
+
   /**
    * Gets the symbol of for the given currency code for the default {@link Locale.Category#DISPLAY
    * DISPLAY} locale. For example, for the US Dollar, the symbol is "$" if the default locale is the