public async Task Should_Return_Merged_Albums_And_Photos_When_Calling_GetAlbumsWithPhotos() { var albumsApiService = new Mock <IAlbumsApiClient>(); albumsApiService.Setup(x => x.GetAlbums()).ReturnsAsync(new List <AlbumConsume>() { new AlbumConsume { Id = 1, Title = "Test", UserId = 1 } }); albumsApiService.Setup(x => x.GetPhotos()).ReturnsAsync(new List <PhotoConsume>() { new PhotoConsume() { Id = 1, AlbumId = 1, Title = "Test Photo", ThumbnailUrl = "something", Url = "something" } }); var albumsService = new AlbumsService(albumsApiService.Object, _mapper); var albums = await albumsService.GetAlbumsWithPhotos(); Assert.Single(albums); Assert.Collection(albums, album => Assert.Single(album.Photos)); }