asp.net - 单元测试操作过滤器 - 如何模拟 ViewResult

Question

我对 SO 进行了搜索，看起来这个问题经常被问到。我已经能够让模拟工作，并且我也能够毫无问题地执行 OnActionExecuted() 。这是我的单元测试。注释行是失败的行，我确信我没有 mock 正确的类型。

        //Arrange
        //var viewResult = new ViewResult();
        var filterContextMock = new Mock<ActionExecutedContext>();
        var routeData = new RouteData();
        var httpContextMock = new Mock<HttpContextBase>();

        routeData.Values["data"] = "Mock data";
        var requestContext = new RequestContext(httpContextMock.Object, routeData);

        var controller = new FakeController();
        controller.ControllerContext = new ControllerContext(requestContext, controller);

        filterContextMock.Setup(f => f.RouteData).Returns(routeData);
        filterContextMock.Setup(f => f.Controller).Returns(controller);
        //filterContextMock.Setup(f => f.Result).Returns(viewResult);

        //Act
        var wrapFilterAttribute = new WrapFilterAttribute();
        wrapFilterAttribute.OnActionExecuted(filterContextMock.Object);

这是我的操作过滤器。

public class WrapFilterAttribute : ActionFilterAttribute
{
    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        var view = (ViewResultBase)filterContext.Result;

        if (view != null)
        {
            BaseViewModel viewModel = (BaseViewModel)view.ViewData.Model ?? new BaseViewModel();
            viewModel.Wrap = new WrapperFactory().GetWrap();
        }

        base.OnActionExecuted(filterContext);
    }
}

我在这里面临的问题是filterContext.Result 始终以EmptyResult 形式出现。我想插入一个水合的 ViewResult。我有什么想法可以实现这一点吗？

非常感谢!

Answer 1

首先让我们从修复操作过滤器开始，因为目前代码看起来很糟糕，并且这些转换可能会给您带来麻烦:

public class WrapFilterAttribute : ActionFilterAttribute
{
    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        var view = filterContext.Result as ViewResultBase;
        if (view != null)
        {
            // the controller action returned a ViewResultBase
            var viewModel = view.ViewData.Model as BaseViewModel;
            if (viewModel != null)
            {
                // the model passed to the view was derived from
                // BaseViewModel so we can safely update the Wrap
                // property
                viewModel.Wrap = new WrapperFactory().GetWrap();
            }
        }
        base.OnActionExecuted(filterContext);
    }
}

以及单元测试:

// arrange
var sut = new WrapFilterAttribute();
var filterContextMock = new Mock<ActionExecutedContext>();
var viewResultMock = new Mock<ViewResultBase>();
filterContextMock.Object.Result = viewResultMock.Object;
var viewModel = new BaseViewModel();
viewResultMock.Object.ViewData.Model = viewModel;

// act
sut.OnActionExecuted(filterContextMock.Object);

// assert
// TODO: assert something on the viewModel.Wrap property like 
// for example that it has been initialized

备注:您的操作过滤器对 WrapperFactory 类有很强的依赖性。不是很好。进一步的改进是将这个功能抽象到一个接口(interface)中，该接口(interface)将被注入(inject)到 Action 过滤器的构造函数中。这将使您能够进一步分离应用程序不同层之间的关注点。