test(firebase_auth): migrate tests to integration_test package

tests/integration_test/e2e_test.dart

@@ -6,12 +6,13 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:integration_test/integration_test.dart';
 
 import 'firebase_core/firebase_core_e2e_test.dart' as firebase_core;
+import 'firebase_auth/firebase_auth_e2e_test.dart' as firebase_auth;
 
 void main() {
   IntegrationTestWidgetsFlutterBinding.ensureInitialized();
 
-  // ignore: unnecessary_lambdas
   group('FlutterFire', () {
     firebase_core.main();
+    firebase_auth.main();
   });
 }

tests/integration_test/firebase_auth/firebase_auth_e2e_test.dart

@@ -0,0 +1,45 @@
+// Copyright 2019, the Chromium project authors.  Please see the AUTHORS file
+// for details. 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:firebase_auth/firebase_auth.dart';
+import 'package:firebase_core/firebase_core.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tests/firebase_options.dart';
+
+import 'test_utils.dart';
+import 'firebase_auth_instance_e2e.dart' as instance_tests;
+import 'firebase_auth_user_e2e.dart' as user_tests;
+
+void main() {
+  group('firebase_auth', () {
+    setUpAll(() async {
+      await Firebase.initializeApp(
+        options: DefaultFirebaseOptions.currentPlatform,
+      );
+      await FirebaseAuth.instance
+          .useAuthEmulator(testEmulatorHost, testEmulatorPort);
+    });
+
+    setUp(() async {
+      // Reset users on emulator.
+      await emulatorClearAllUsers();
+      // Create a generic testing user account.
+      await FirebaseAuth.instance.createUserWithEmailAndPassword(
+        email: testEmail,
+        password: testPassword,
+      );
+      // Create a disabled user account.
+      final disabledUserCredential =
+          await FirebaseAuth.instance.createUserWithEmailAndPassword(
+        email: testDisabledEmail,
+        password: testPassword,
+      );
+      await emulatorDisableUser(disabledUserCredential.user!.uid);
+      await ensureSignedOut();
+    });
+
+    instance_tests.main();
+    user_tests.main();
+  });
+}