asp.net - 将ActionResult强制转换为HttpNotFoundResult返回null

我对 Controller 进行了单元测试，该测试断言在未找到模型实例时返回HttpNotFoundResult。问题是， Controller 中的实际代码可以按预期工作，但是我的单元测试却没有。将ActionResult转换为HttpNotFoundResult时，它返回null，因此我的单元测试失败。

Controller 代码:

public ActionResult Delete(int? id)
        {
            if(id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            Forum forum = forumRepository.GetForumById(id.GetValueOrDefault());
            if(forum == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.NotFound);
            }
            return View(forum);
        }

测试方法:

 [TestMethod]
        public void GetDeleteShouldReturn404IfForumNotFound()
        {
            // Arrange
            var forumRepository = Mock.Create<IForumRepository>();
            Mock.Arrange(() => forumRepository.GetForums())
                .Returns(new List<Forum>() {
                    new Forum { ForumId = 1, Title = "General Forum", Description = "Place to discuss general stuff", Sequence = 2 },
                    new Forum { ForumId = 2, Title = "Gaming", Description = "Let's talk about gaming", Sequence = 1 },
                    new Forum { ForumId = 3, Title = "Web Development", Description = "ASP.NET is pretty cool", Sequence = 3 }
                }).MustBeCalled();

            // Act
            ForumController controller = new ForumController(forumRepository);
            ActionResult result = controller.Delete(5) as HttpNotFoundResult;

            // Assert
            Assert.IsNotNull(result);
            Assert.IsInstanceOfType(result, typeof(HttpNotFoundResult));
        }

Assert.IsNotNull失败。我也尝试了以下相同的结果:

HttpNotFoundResult result = controller.Delete(5) as HttpNotFoundResult;

这让我很困惑，因为我在几个示例中看到了几乎相同的代码:

http://weblogs.asp.net/gunnarpeipman/archive/2010/08/15/asp-net-mvc-3-using-httpnotfoundresult-in-controller-tests.aspx

我做错什么了吗？

编辑:

问题是我没有 mock GetForumById()，而是将测试代码更改为以下工作方式:

[TestMethod]
        public void GetDeleteShouldReturn404IfForumNotFound()
        {
            // Arrange
            var id = 10;
            Forum forum = null;

            var forumRepository = Mock.Create<IForumRepository>();

            Mock.Arrange(() => forumRepository.GetForumById(id))
                .Returns(forum)
                .MustBeCalled();

            // Act
            ForumController controller = new ForumController(forumRepository);
            var result = controller.Delete(id) as HttpNotFoundResult;

            // Assert
            Assert.IsNotNull(result);
            Assert.IsInstanceOfType(result, typeof(HttpNotFoundResult));
        }

最佳答案

这是因为HttpNotFoundResult源自HttpStatusCodeResult，而不是相反。您正在进行无效的下调，这会使as语句返回null。

关于asp.net - 将ActionResult强制转换为HttpNotFoundResult返回null，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/22380784/