Add dart side code to call getBillingConfig and conversion tests

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

@@ -232,6 +232,9 @@ static HashMap<String, Object> fromBillingResult(BillingResult billingResult) {
     return info;
   }
 
+  /**
+   * Converter from {@link BillingResult} and {@link BillingConfig} to map.
+   */
   static HashMap<String, Object> fromBillingConfig(BillingResult result, BillingConfig billingConfig) {
     HashMap<String, Object> info = fromBillingResult(result);
     info.put("countryCode", billingConfig.getCountryCode());

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

@@ -10,6 +10,7 @@ import 'package:json_annotation/json_annotation.dart';
 
 import '../../billing_client_wrappers.dart';
 import '../channel.dart';
+import 'billing_config_wrapper.dart';
 
 part 'billing_client_wrapper.g.dart';
 
@@ -324,6 +325,17 @@ class BillingClient {
     return result ?? false;
   }
 
+  @visibleForTesting
+  final String getBillingConfigMethodString =
+      'BillingClient#getBillingConfig()';
+
+  /// TODO
+  Future<BillingConfigWrapper> getBillingConfig() async {
+    return BillingConfigWrapper.fromJson((await channel
+            .invokeMapMethod<String, dynamic>(getBillingConfigMethodString)) ??
+        <String, dynamic>{});
+  }
+
   /// The method call handler for [channel].
   @visibleForTesting
   Future<void> callHandler(MethodCall call) async {

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

@@ -0,0 +1,74 @@
+// 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/material.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 'billing_config_wrapper.g.dart';
+
+/// The error message shown when the map represents billing config is invalid from method channel.
+///
+/// This usually indicates a serious underlining code issue in the plugin.
+@visibleForTesting
+const String kInvalidBillingConfigErrorMessage =
+    'Invalid billing config map from method channel.';
+
+/// Params containing the response code and the debug message from the Play Billing API response.
+@JsonSerializable()
+@BillingResponseConverter()
+@immutable
+class BillingConfigWrapper implements HasBillingResponse {
+  /// Constructs the object with [responseCode] and [debugMessage].
+  const BillingConfigWrapper({required this.responseCode, this.debugMessage, this.countryCode});
+
+  /// Constructs an instance of this from a key value map of data.
+  ///
+  /// The map needs to have named string keys with values matching the names and
+  /// types of all of the members on this class.
+  factory BillingConfigWrapper.fromJson(Map<String, dynamic>? map) {
+    if (map == null || map.isEmpty) {
+      return const BillingConfigWrapper(
+          responseCode: BillingResponse.error,
+          debugMessage: kInvalidBillingResultErrorMessage,
+          countryCode: '',
+          );
+    }
+    return _$BillingConfigWrapperFromJson(map);
+  }
+
+  /// Response code returned in the Play Billing API calls.
+  @override
+  final BillingResponse responseCode;
+
+  /// Debug message returned in the Play Billing API calls.
+  ///
+  /// Defaults to `null`.
+  /// This message uses an en-US locale and should not be shown to users.
+  @JsonKey(defaultValue: '')
+  final String? debugMessage;
+
+  /// https://developer.android.com/reference/com/android/billingclient/api/BillingConfig#getCountryCode()
+  @JsonKey(defaultValue: '')
+  final String? countryCode;
+
+  @override
+  bool operator ==(Object other) {
+    if (other.runtimeType != runtimeType) {
+      return false;
+    }
+
+    return other is BillingConfigWrapper &&
+        other.responseCode == responseCode &&
+        other.debugMessage == debugMessage &&
+        other.countryCode == countryCode;
+  }
+
+  @override
+  int get hashCode => Object.hash(responseCode, debugMessage, countryCode);
+}

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

@@ -7,6 +7,7 @@ import 'package:in_app_purchase_platform_interface/in_app_purchase_platform_inte
 
 import '../billing_client_wrappers.dart';
 import '../in_app_purchase_android.dart';
+import 'billing_client_wrappers/billing_config_wrapper.dart';
 
 /// Contains InApp Purchase features that are only available on PlayStore.
 class InAppPurchaseAndroidPlatformAddition
@@ -146,4 +147,11 @@ class InAppPurchaseAndroidPlatformAddition
       (BillingClient client) => client.isFeatureSupported(feature),
     );
   }
+
+  /// TODO
+  Future<BillingConfigWrapper> getBillingConfig() async {
+    return _billingClientManager.runWithClientNonRetryable(
+      (BillingClient client) => client.getBillingConfig(),
+    );
+  }
 }

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

@@ -5,6 +5,7 @@
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:in_app_purchase_android/billing_client_wrappers.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 '../stub_in_app_purchase_platform.dart';
@@ -641,6 +642,39 @@ void main() {
       expect(arguments['feature'], equals('subscriptions'));
     });
   });
+
+  group('billingConfig', () {
+    const String billingConfigMethodName = 'BillingClient#getBillingConfig()';
+    test('billingConfig returns object', () async {
+      late Map<Object?, Object?> arguments;
+      stubPlatform.addResponse(
+        name: billingConfigMethodName,
+        value: const BillingConfigWrapper(
+            countryCode: 'US',
+            responseCode: BillingResponse.ok,
+            debugMessage: ''),
+        additionalStepBeforeReturn: (dynamic value) =>
+            arguments = value as Map<dynamic, dynamic>,
+      );
+      final BillingConfigWrapper result =
+          await billingClient.getBillingConfig();
+      expect(result.countryCode, 'US');
+    });
+
+
+    test('handles method channel returning null', () async {
+      stubPlatform.addResponse(
+        name: billingConfigMethodName,
+      );
+      final BillingConfigWrapper result =
+          await billingClient.getBillingConfig();
+      expect(
+          result,
+          equals(const BillingConfigWrapper(
+              responseCode: BillingResponse.error,
+              debugMessage: kInvalidBillingConfigErrorMessage)));
+    });
+  });
 }
 
 /// This allows a value of type T or T? to be treated as a value of type T?.

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

@@ -4,6 +4,7 @@
 
 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:test/test.dart';
 
 const PurchaseWrapper dummyPurchase = PurchaseWrapper(
@@ -252,3 +253,12 @@ Map<String, dynamic> buildBillingResultMap(BillingResultWrapper original) {
     'debugMessage': original.debugMessage,
   };
 }
+
+Map<String, dynamic> buildBillingConfigMap(BillingConfigWrapper original) {
+  return <String, dynamic>{
+    'responseCode':
+        const BillingResponseConverter().toJson(original.responseCode),
+    'debugMessage': original.debugMessage,
+    'countryCode': original.countryCode,
+  };
+}