How can I access the Firebase Flutter plugin from a test?

Question

I want to run the real Firebase (not a mock) during a Flutter test. I'm trying to authenticate Firebase with FirebaseOptions:

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_core/firebase_core.dart';
import "package:test/test.dart";

Future<void> main() async {
  final FirebaseApp app = await FirebaseApp.configure(
    name: 'test',
    options: const FirebaseOptions(
      googleAppID: 'xxxxxxx',
      projectID: 'yyyyyy',
    ),
  );
  final Firestore firestore = Firestore(app: app);
  await firestore.settings(timestampsInSnapshotsEnabled: true);

  test('Testing access.', () async {
    final FirebaseAuth _auth = FirebaseAuth.instance;
    FirebaseUser user = await _auth.signInAnonymously();

    firestore.collection('aaaaa').document('bbbbb').get().then((documentSnaphot) {
      expect(documentSnaphot['xxxx'], 'ccccc');
    });
  });
}

However, I'm getting the following error:

Failed to load "C:\Users\Ed\testing\app\test\user_test.dart": 
MissingPluginException(No implementation found for method 
FirebaseApp#appNamed on channel plugins.flutter.io/firebase_core)


package:flutter/src/services/platform_channel.dart 278:7                                                    
MethodChannel.invokeMethod

===== asynchronous gap ===========================

c: 38:53                                                                                                    
FirebaseApp.appNamed

===== asynchronous gap ===========================

c: 64:55                                                                                                    
FirebaseApp.configure

===== asynchronous gap ===========================

test\usuario_test.dart 7:45                                                                                 
main

===== asynchronous gap ===========================

package:test                                                                                                
serializeSuite

..\..\..\AppData\Local\Temp\flutter_test_listener.64a30b51-eb69-11e8-
a427-1831bf4c06e8\listener.dart 19:27  main

How can I solve this?

Solution

Plugins run only on mobile devices (or emulators).
To make testing code that uses plugins possible, you can register your own handlers that respond to method channel requests like the native side of plugins would

test('gets greeting from platform', () async {
  const channel = MethodChannel('foo');
  channel.setMockMethodCallHandler((MethodCall call) async {
    if (call.method == 'bar')
      return 'Hello, ${call.arguments}';
    throw MissingPluginException();
  });
  expect(await hello('world'), 'Platform says: Hello, world');
});

From the last section of https://medium.com/flutter-io/flutter-platform-channels-ce7f540a104e

Comments

[Eduardo Yamauchi]

Thanks Gunter, but as I said, I want to test a real Firebase (not a mock). Maybe it works if I use flutter run instead of flutter test ?

[Günter Zöchbauer]

Then you have to run the test on an emulator. Yes with flutter run it will work.