我正在尝试测试我编写的一些HtmlHelper
扩展方法。我的第一个问题是如何创建HtmlHelper
实例,但我使用以下代码解决了该问题:
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);
}
我的几个测试现在可以正常工作,但是有一个测试引发了异常。该测试定义如下:
// Arrange
var inputDictionary = CreateDictionary();
var htmlHelper = CreateHtmlHelper(inputDictionary);
// Act
var actualHtmlString = htmlHelper.EditorFor(m => m.Dict, model).ToHtmlString();
...
EditorFor
方法是我的扩展方法。在该方法的某个位置进行了以下调用:tagBuilder.MergeAttributes(htmlHelper.GetUnobtrusiveValidationAttributes(expression, metadata));
从我的单元测试中执行此代码时,将引发以下异常:
System.NullReferenceExceptionObject reference not set to an instance of an object.
at System.Web.Mvc.ViewContext.ScopeCache.Get(IDictionary`2 scope, HttpContextBase httpContext)
at System.Web.Mvc.ViewContext.get_UnobtrusiveJavaScriptEnabled()
at System.Web.Mvc.HtmlHelper.GetUnobtrusiveValidationAttributes(String name, ModelMetadata metadata)
at AspNetMvcDictionarySerialization.HtmlHelperExtensions.InputTagHelper(HtmlHelper htmlHelper, ModelMetadata metadata, InputType inputType, String expression, IDictionary`2 htmlAttributes, String fullName, Int32 index, String fieldType, String val) in HtmlHelperExtensions.cs: line 154
因此,代码在
ScopeCache.Get
中失败,但是为什么呢?有谁知道如何解决这个问题? 最佳答案
我最终要做的是看source code of ASP.NET MVC。在他们的代码中,他们还测试了HtmlHelper
实例。他们使用名为MvcHelper
的实用程序类来执行此操作,该实用程序类提供了方便的方法来使用正确准备的HTTP上下文创建新的HtmlHelper
实例。
在删除了不需要的代码之后,我得到了以下类(class):
public static class MvcHelper
{
public static HtmlHelper<TModel> GetHtmlHelper<TModel>(TModel inputDictionary)
{
var viewData = new ViewDataDictionary<TModel>(inputDictionary);
var mockViewContext = new Mock<ViewContext> { CallBase = true };
mockViewContext.Setup(c => c.ViewData).Returns(viewData);
mockViewContext.Setup(c => c.HttpContext.Items).Returns(new Hashtable());
return new HtmlHelper<TModel>(mockViewContext.Object, GetViewDataContainer(viewData));
}
public static IViewDataContainer GetViewDataContainer(ViewDataDictionary viewData)
{
var mockContainer = new Mock<IViewDataContainer>();
mockContainer.Setup(c => c.ViewData).Returns(viewData);
return mockContainer.Object;
}
}
有了这个帮助器类,我的代码可以正确执行。
我为完整的帮助程序类创建了要点,以便于轻松包含在您的项目中:https://gist.github.com/ErikSchierboom/6da474dcd5751fbbc94c