public void GetFirstNameByIdShouldReturnFalse() { var posts = new List <Post>(); var appUsers = new List <ApplicationUser>(); var mockPostRepo = new Mock <IDeletableEntityRepository <Post> >(); mockPostRepo.Setup(x => x.All()).Returns(posts.AsQueryable()); mockPostRepo.Setup(x => x.AddAsync(It.IsAny <Post>())).Callback((Post post) => posts.Add(post)); var mockAppUser = new Mock <IDeletableEntityRepository <ApplicationUser> >(); mockAppUser.Setup(x => x.All()).Returns(appUsers.AsQueryable()); mockAppUser.Setup(x => x.AddAsync(It.IsAny <ApplicationUser>())).Callback((ApplicationUser appU) => appUsers.Add(appU)); var service = new PostsService(mockAppUser.Object, mockPostRepo.Object); var post = new Post { Id = "1", UserId = "1", Content = "Test", Title = "Test", SentById = "1", }; posts.Add(post); var appUser = new ApplicationUser { Id = "1", UserCharacteristics = new UserCharacteristic { FirstName = "Pesho", }, }; var secondAppUser = new ApplicationUser { Id = "2", }; appUsers.Add(appUser); var result = service.GetFirstNameById("2"); Assert.Equal(false, result); }