Add method channel setup tests

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

@@ -2,19 +2,126 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+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/in_app_purchase_android.dart';
 import 'package:in_app_purchase_platform_interface/in_app_purchase_platform_interface.dart';
 import 'package:integration_test/integration_test.dart';
 
 void main() {
   IntegrationTestWidgetsFlutterBinding.ensureInitialized();
 
+  setUp(() {
+    InAppPurchaseAndroidPlatform.registerPlatform();
+  });
+
   testWidgets('Can create InAppPurchaseAndroid instance',
       (WidgetTester tester) async {
-    InAppPurchaseAndroidPlatform.registerPlatform();
     final InAppPurchasePlatform androidPlatform =
         InAppPurchasePlatform.instance;
     expect(androidPlatform, isNotNull);
   });
+
+  group('Method channel interaction works for', () {
+    late final BillingClient billingClient;
+
+    setUpAll(() {
+      billingClient = BillingClient((PurchasesResultWrapper _) {});
+    });
+
+    test('BillingClient.acknowledgePurchase', () async {
+      try {
+        await billingClient.acknowledgePurchase('purchaseToken');
+      } on MissingPluginException {
+        fail('Method channel is not setup correctly');
+      }
+    });
+
+    test('BillingClient.consumeAsync', () async {
+      try {
+        await billingClient.consumeAsync('purchaseToken');
+      } on MissingPluginException {
+        fail('Method channel is not setup correctly');
+      }
+    });
+
+    test('BillingClient.endConnection', () async {
+      try {
+        await billingClient.endConnection();
+      } on MissingPluginException {
+        fail('Method channel is not setup correctly');
+      }
+    });
+
+    test('BillingClient.isFeatureSupported', () async {
+      try {
+        await billingClient
+            .isFeatureSupported(BillingClientFeature.productDetails);
+      } on MissingPluginException {
+        fail('Method channel is not setup correctly');
+      }
+    });
+
+    test('BillingClient.isReady', () async {
+      try {
+        await billingClient.isReady();
+      } on MissingPluginException {
+        fail('Method channel is not setup correctly');
+      }
+    });
+
+    test('BillingClient.launchBillingFlow', () async {
+      try {
+        await billingClient.launchBillingFlow(product: 'product');
+      } on MissingPluginException {
+        fail('Method channel is not setup correctly');
+      } on PlatformException catch (e) {
+        // A [PlatformException] is expected, as we do not fetch products first.
+        if (e.code != 'NOT_FOUND') {
+          rethrow;
+        }
+      }
+    });
+
+    test('BillingClient.queryProductDetails', () async {
+      try {
+        await billingClient
+            .queryProductDetails(productList: <ProductWrapper>[]);
+      } on MissingPluginException {
+        fail('Method channel is not setup correctly');
+      } on PlatformException catch (e) {
+        // A [PlatformException] is expected, as we send an empty product list.
+        if (!(e.message?.startsWith('Product list cannot be empty.') ??
+            false)) {
+          rethrow;
+        }
+      }
+    });
+
+    test('BillingClient.queryPurchaseHistory', () async {
+      try {
+        await billingClient.queryPurchaseHistory(ProductType.inapp);
+      } on MissingPluginException {
+        fail('Method channel is not setup correctly');
+      }
+    });
+
+    test('BillingClient.queryPurchases', () async {
+      try {
+        await billingClient.queryPurchases(ProductType.inapp);
+      } on MissingPluginException {
+        fail('Method channel is not setup correctly');
+      }
+    });
+
+    test('BillingClient.startConnection', () async {
+      try {
+        await billingClient.startConnection(
+            onBillingServiceDisconnected: () {});
+      } on MissingPluginException {
+        fail('Method channel is not setup correctly');
+      }
+    });
+  });
 }