public async Task AddFriendRequest_RequestedByUserIsNull_ReturnNotFound() { _userService.Setup(us => us.GetUserByIdAsync(It.IsAny <string>())).ReturnsAsync(() => null); var result = await _friendController.AddFriendRequest(It.IsAny <string>()) as NotFoundResult; Assert.That(result, Is.TypeOf <NotFoundResult>()); }