public void TestIf_DoesArticleExist_ReturnsFalse() { var articleRepository = new Mock <IRepository <Article> >(); articleRepository.Setup(p => p.All()).Returns(new List <Article> { new Article { Id = 2 } } .AsQueryable()); var articleService = new ArticleService(articleRepository.Object, null, null, null, null, null); Assert.False(articleService.DoesArticleExist(1)); }