public async void GetUserAccountById_Return_NotFound() { //Arange _mockUserAccountProvider.Setup(x => x.GetUserAccountListById(It.IsAny <long>())).Returns(Task.FromResult((IEnumerable <UserAccountAllParam>)null)); //Act var result = await _controller.GetuserAccountById(1).ConfigureAwait(false); //Assert Assert.NotNull(result); Assert.IsType <NotFoundResult>(result); }