相关疑难解决方法(0)

我正在尝试测试HtmlHelper我编写的一些扩展方法.我的第一个问题是如何创建一个HtmlHelper实例,但我使用这个代码解决了这个问题:

private static HtmlHelper<T> CreateHtmlHelper<T>(T model)
{
    var viewDataDictionary = new ViewDataDictionary(model);
    var controllerContext = new ControllerContext(new Mock<HttpContextBase>().Object,
    new RouteData(),
    new Mock<ControllerBase>().Object);

    var viewContext = new ViewContext(controllerContext, new Mock<IView>().Object, viewDataDictionary, new TempDataDictionary(), new Mock<TextWriter>().Object);

    var mockViewDataContainer = new Mock<IViewDataContainer>();
mockViewDataContainer.Setup(v => v.ViewData).Returns(viewDataDictionary);

    return new HtmlHelper<T>(viewContext, mockViewDataContainer.Object);
}

我的几个测试现在工作正常,但有一个测试会引发异常.测试定义如下:

// Arrange
var inputDictionary = CreateDictionary();
var htmlHelper = CreateHtmlHelper(inputDictionary);

// Act
var actualHtmlString = htmlHelper.EditorFor(m => m.Dict, model).ToHtmlString();
...

该EditorFor方法是我的扩展方法.在该方法的某处,进行以下调用:

tagBuilder.MergeAttributes(htmlHelper.GetUnobtrusiveValidationAttributes(expression, metadata));    

从我的单元测试执行此代码时,抛出以下异常:

System.NullReferenceExceptionObject reference …