public void ShouldAddPostLikeWhenPostNotYetLikedByUser() { var postLike = new PostLike { PostLikeId = 4, PostId = 1, UserId = 1, User = new User { UserId = 1, UserName = "******" } }; _postLikeRepository = new Mock<IPostLikeRepository>(); _postLikeRepository.Setup(a => a.Find(It.IsAny<Expression<Func<PostLike, bool>>>(), false)) .Returns(new List<PostLike>()); _postLikeRepository.Setup(a => a.Add(It.IsAny<PostLike>())) .Returns(postLike); _postLikesLogic = new PostLikesLogic(_postLikeRepository.Object); var result = _postLikesLogic.Add(new Common.Contracts.PostLike { PostId = 1, UserId = 1 }); Assert.NotNull(result); Assert.AreEqual(4, result.PostLikeId); }