public void TestGetAllArticlesByUser() { List <Article> articles = new List <Article>(); articles.Add(article); IEnumerable <Article> _iEnumerableArticle = articles; mockArticleService.Setup(x => x.GetAllArticlesByUser(It.IsAny <string>(), It.IsAny <PostFilter>(), It.IsAny <int>())).Returns(_iEnumerableArticle); var _articleController = new ArticleController(mockArticleService.Object, mockPostService.Object); IActionResult getAllArticlesByUser = _articleController.GetAllArticlesByUser("5d247a04eff1030d7c520a111", postFilter, 4); var type = getAllArticlesByUser.GetType(); Assert.AreEqual(type.Name, "OkObjectResult"); }