public void PageControllerPut_Should_ReturnBadReqWhenModelNotValid() { var mockRepo = new Mock <IPageRepository>(); var mockLogger = new Mock <ILogger <PageApiController> >(); var page = new Page() { PageId = 1, AddedDate = DateTime.Now }; mockRepo.Setup(r => r.Update(page)); var repo = mockRepo.Object; var controller = new PageApiController(repo, mockLogger.Object); controller.ModelState.AddModelError("Content", "Required"); var res = controller.PostPage(page).Result; var error = Assert.IsType <BadRequestObjectResult>(res); Assert.IsType <SerializableError>(error.Value); }