unit-testing - 对ActionFilter进行单元测试-正确设置ActionExecutingContext

Question

在自定义ActionFilter中，我要检查将要执行的 Controller 操作的属性。在一个小型测试应用程序中运行时，在asp.net开发服务器中启动该应用程序时，以下方法可以正常工作-

public class CustomActionFilterAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        var someAttribute = filterContext.ActionDescriptor
                                    .GetCustomAttributes(typeof(SomeAttribute), false)
                                    .Cast<SomeAttribute>()
                                    .SingleOrDefault();

        if (someAttribute == null)
        {
            throw new ArgumentException();
        }

        // do something here
    }

    public override void OnActionExecuted(ActionExecutingContext filterContext)
    {
        // ...
    }
}

没有 SomeAttribute的操作方法将抛出 ArgumentException，相反，具有 SomeAttribute的操作方法则不会。到现在为止还挺好。

现在，我想为ActionFilter设置一些单元测试，但是如何设置在单元测试中应在其上运行 OnActionExecuting方法的action方法呢？使用以下代码在要执行的操作方法上找不到 SomeAttribute。测试设置正确吗？我在考试中安排的东西不正确吗？为了澄清，测试尚未完成，但是我不确定我错过了什么，因此测试中 someAttribute中的 OnActionExecuting是 null

    [TestMethod]
    public void Controller_With_SomeAttribute()
    {
        FakeController fakeController =
            new FakeController();

        ControllerContext controllerContext = 
            new ControllerContext(new Mock<HttpContextBase>().Object, 
                                  new RouteData(), 
                                  fakeController);

        var actionDescriptor = new Mock<ActionDescriptor>();
        actionDescriptor.SetupGet(x => x.ActionName).Returns("Action_With_SomeAttribute");

        ActionExecutingContext actionExecutingContext =
            new ActionExecutingContext(controllerContext,
                                       actionDescriptor.Object, 
                                       new RouteValueDictionary());

        CustomActionFilterAttribute customActionFilterAttribute = new CustomActionFilterAttribute ();
        customActionFilterAttribute.OnActionExecuting(actionExecutingContext);
    }

    private class FakeController : Controller
    {
        [SomeAttribute]
        ActionResult Action_With_SomeAttribute()
        {
            return View();
        }
    }

Answer 1

由于ActionExecutingContext的ActionDescriptor属性是虚拟的，因此您可以仅提供override并提供自己的ActionDescriptor实现。

这是两个测试，它们通过OnActionExecuting的当前实现来验证两个分支:

[ExpectedException(typeof(ArgumentException))]
[TestMethod]
public void OnActionExecutingWillThrowWhenSomeAttributeIsNotPresent()
{
    // Fixture setup
    var ctxStub = new Mock<ActionExecutingContext>();
    ctxStub.Setup(ctx => ctx.ActionDescriptor.GetCustomAttributes(typeof(SomeAttribute), false))
        .Returns(new object[0]);

    var sut = new CustomActionFilterAttribute();
    // Exercise system
    sut.OnActionExecuting(ctxStub.Object);
    // Verify outcome (expected exception)
    // Teardown
}

[TestMethod]
public void OnActionExecutingWillNotThrowWhenSomeAttributeIsPresent()
{
    // Fixture setup
    var ctxStub = new Mock<ActionExecutingContext>();
    ctxStub.Setup(ctx => ctx.ActionDescriptor.GetCustomAttributes(typeof(SomeAttribute), false))
        .Returns(new object[] { new SomeAttribute() });

    var sut = new CustomActionFilterAttribute();
    // Exercise system
    sut.OnActionExecuting(ctxStub.Object);
    // Verify outcome (no exception indicates success)
    // Teardown
}