public async Task DeletePhotoShouldWorkCorrectly() { var photos = new List <Photo>(); var mockPhoto = new Mock <IDeletableEntityRepository <Photo> >(); mockPhoto.Setup(x => x.All()).Returns(photos.AsQueryable()); mockPhoto.Setup(x => x.AddAsync(It.IsAny <Photo>())).Callback((Photo ph) => photos.Add(ph)); var service = new AdminsService(null, null, mockPhoto.Object, null, null); var photo = new Photo { Id = "123", }; photos.Add(photo); await service.DeletePhoto("123"); Assert.Equal(true, photo.IsDeleted); }