How to mock VideoPlayerController.network() in Flutter

Question

I'm writing a simple test for my video player widget that uses the video_player plugin. I'm not able to mock the network request made by the video controller for fetching the video over network. My widget code looks like:

late VideoPlayerController _videoController;

@override
void initState() {
    _videoController = VideoPlayerController.network(widget.videoUrl);
// rest of the code
}

and test code:

VideoPlayerController _videoController =
        VideoPlayerController.network(videoUrl);

    when(VideoPlayerController.network(videoUrl))
        .thenAnswer((_) => _videoController);

This is not working because it is not able to stub the network request method correctly. Any ideas for mocking it correctly? I have several other tests in my code where I have mocked my api client class which makes network requests, but this one is a little different. I'm using mockito for mocking.

Please help!

Answer 1

Solution : This is how you can mock the video_player package.

// On unit test, you can use following
VideoPlayerPlatform.instance = FakeVideoPlayerPlatform();

import 'dart:async';

import 'package:flutter/services.dart';
import 'package:flutter/widgets.dart';

// For unit test
// ignore: depend_on_referenced_packages
import 'package:video_player_platform_interface/video_player_platform_interface.dart';

// Created from video_player package and video_player_test.dart file.
class FakeVideoPlayerPlatform extends VideoPlayerPlatform {
  final Completer<bool> initialized = Completer<bool>();
  final List<String> calls = <String>[];
  final List<DataSource> dataSources = <DataSource>[];
  final Map<int, StreamController<VideoEvent>> streams =
      <int, StreamController<VideoEvent>>{};
  final bool forceInitError;
  int nextTextureId = 0;
  final Map<int, Duration> _positions = <int, Duration>{};

  FakeVideoPlayerPlatform({
    this.forceInitError = false,
  });

  @override
  Future<int?> create(DataSource dataSource) async {
    calls.add('create');
    final StreamController<VideoEvent> stream = StreamController<VideoEvent>();
    streams[nextTextureId] = stream;
    if (forceInitError) {
      stream.addError(
        PlatformException(
          code: 'VideoError',
          message: 'Video player had error XYZ',
        ),
      );
    } else {
      stream.add(
        VideoEvent(
          eventType: VideoEventType.initialized,
          size: const Size(100, 100),
          duration: const Duration(seconds: 1),
        ),
      );
    }
    dataSources.add(dataSource);
    return nextTextureId++;
  }

  @override
  Future<void> dispose(int textureId) async {
    calls.add('dispose');
  }

  @override
  Future<void> init() async {
    calls.add('init');
    initialized.complete(true);
  }

  @override
  Stream<VideoEvent> videoEventsFor(int textureId) {
    return streams[textureId]!.stream;
  }

  @override
  Future<void> pause(int textureId) async {
    calls.add('pause');
  }

  @override
  Future<void> play(int textureId) async {
    calls.add('play');
  }

  @override
  Future<Duration> getPosition(int textureId) async {
    calls.add('position');
    return _positions[textureId] ?? Duration.zero;
  }

  @override
  Future<void> seekTo(int textureId, Duration position) async {
    calls.add('seekTo');
    _positions[textureId] = position;
  }

  @override
  Future<void> setLooping(int textureId, bool looping) async {
    calls.add('setLooping');
  }

  @override
  Future<void> setVolume(int textureId, double volume) async {
    calls.add('setVolume');
  }

  @override
  Future<void> setPlaybackSpeed(int textureId, double speed) async {
    calls.add('setPlaybackSpeed');
  }

  @override
  Future<void> setMixWithOthers(bool mixWithOthers) async {
    calls.add('setMixWithOthers');
  }

  @override
  Widget buildView(int textureId) {
    return Texture(textureId: textureId);
  }
}