Flutter unit testing firestore

Question

I'm new to unit testing in general. I'm trying to test simple method from my DataRepository.

Following this link but seems deprecated: https://utkarshkore.medium.com/writing-unit-tests-in-flutter-with-firebase-firestore-72f99be85737

class DataRepository {
  final CollectionReference collection =
      FirebaseFirestore.instance.collection('notes');

  //Retour de models a la place de snapshots
  Stream<QuerySnapshot> getStream() {
    return collection.snapshots();
  }

  Stream<QuerySnapshot> getStreamDetail(String id) {
    return collection.doc(id).collection('tasks').snapshots();
  }

  Stream<List<Note>> noteStream() {
    final CollectionReference collection =
        FirebaseFirestore.instance.collection('notes');

    try {
      return collection.snapshots().map((notes) {
        final List<Note> notesFromFirestore = <Note>[];
        for (var doc in notes.docs) {
          notesFromFirestore.add(Note.fromSnapshot(doc));
        }
        return notesFromFirestore;
      });
    } catch (e) {
      rethrow;
    }
  }

So far this is what my test file look like:

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:mockito/mockito.dart';

class MockFirestore extends Mock implements FirebaseFirestore {}
class MockCollectionReference extends Mock implements CollectionReference {}

void main() {
  MockFirestore instance = MockFirestore();
  MockCollectionReference mockCollectionReference = MockCollectionReference();

  test('should return data when the call to remote source is succesful.',
      () async {
    when(instance.collection('notes')).thenReturn(mockCollectionReference);
  });
}

First instance throw me this error

The argument type 'MockCollectionReference' can't be assigned to the parameter type 'CollectionReference<Map<String, dynamic>>'

I would really appreciate the help for testing the method.

new edit:

void main() {
  test('should return data when the call to remote source is succesful.',
      () async {
    final FakeFirebaseFirestore fakeFirebaseFirestore = FakeFirebaseFirestore();
    final DataRepository dataRepository = DataRepository();
    final CollectionReference mockCollectionReference =
        fakeFirebaseFirestore.collection(dataRepository.collection.path);

    final List<Note> mockNoteList = <Note>[];

    for (Note mockNote in mockNoteList) {
      await mockCollectionReference.add(mockNote.toJson());
    }

    final Stream<List<Note>> noteStreamFromRepository =
        dataRepository.noteStream();

    final List<Note> actualNoteList = await noteStreamFromRepository.first;
    final List<Note> expectedNoteList = mockNoteList;

    expect(actualNoteList, expectedNoteList);
  });
}

Answer 1

This should solve your problem: Specify a type for CollectionReference. This way:

class MockCollectionReference extends Mock implements CollectionReference<Map<String, dynamic>> {}