如何在ASP.NET MVC3中测试ValueProviderFactories？

Question

我们想将项目从ASP.NET MVC 2升级到3。我们的大多数测试都成功了，但是有些测试失败了 ValueProviderFactories.Factories.GetValueProvider(context).

这是一个简单的测试类，可以解决问题。

[TestFixture]
public class FailingTest
{
  [Test]
  public void Test()
  {
    var type = typeof(string);
    // any controller
    AuthenticationController c = new AuthenticationController();
    var httpContext = new Mock<HttpContextBase>();
    var context = c.ControllerContext = new ControllerContext(httpContext.Object, new RouteData(), c);

    IModelBinder converter = ModelBinders.Binders.GetBinder(type);
    var bc = new ModelBindingContext
    {
      ModelName = "testparam",
      ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(null, type),
      ValueProvider = ValueProviderFactories.Factories.GetValueProvider(context)
    };
    Console.WriteLine(converter.BindModel(context, bc));
  }
}

异常“对象引用未设置为对象的实例”。在 ValueProviderFactories.Factories.GetValueProvider(context) 叫做。堆栈看起来像这样：

Microsoft.Web.Infrastructure.dll!Microsoft.Web.Infrastructure.DynamicValidationHelper.ValidationUtility.CollectionReplacer.GetUnvalidatedCollections(System.Web.HttpContext context) + 0x23 bytes   
Microsoft.Web.Infrastructure.dll!Microsoft.Web.Infrastructure.DynamicValidationHelper.ValidationUtility.GetUnvalidatedCollections(System.Web.HttpContext context, out System.Collections.Specialized.NameValueCollection form, out System.Collections.Specialized.NameValueCollection queryString, out System.Collections.Specialized.NameValueCollection headers, out System.Web.HttpCookieCollection cookies) + 0xbe bytes    
System.Web.WebPages.dll!System.Web.Helpers.Validation.Unvalidated(System.Web.HttpRequest request) + 0x73 bytes  
System.Web.WebPages.dll!System.Web.Helpers.Validation.Unvalidated(System.Web.HttpRequestBase request) + 0x25 bytes  
System.Web.Mvc.DLL!System.Web.Mvc.FormValueProviderFactory..ctor.AnonymousMethod__0(System.Web.Mvc.ControllerContext cc) + 0x5a bytes   
System.Web.Mvc.DLL!System.Web.Mvc.FormValueProviderFactory.GetValueProvider(System.Web.Mvc.ControllerContext controllerContext) + 0xa0 bytes    
System.Web.Mvc.DLL!System.Web.Mvc.ValueProviderFactoryCollection.GetValueProvider.AnonymousMethod__7(System.Web.Mvc.ValueProviderFactory factory) + 0x4a bytes  
System.Core.dll!System.Linq.Enumerable.WhereSelectEnumerableIterator<System.Web.Mvc.ValueProviderFactory,<>f__AnonymousType2<System.Web.Mvc.ValueProviderFactory,System.Web.Mvc.IValueProvider>>.MoveNext() + 0x24d bytes   
System.Core.dll!System.Linq.Enumerable.WhereSelectEnumerableIterator<<>f__AnonymousType2<System.Web.Mvc.ValueProviderFactory,System.Web.Mvc.IValueProvider>,System.Web.Mvc.IValueProvider>.MoveNext() + 0x2ba bytes 
mscorlib.dll!System.Collections.Generic.List<System.Web.Mvc.IValueProvider>.List(System.Collections.Generic.IEnumerable<System.Web.Mvc.IValueProvider> collection) + 0x1d8 bytes    
System.Core.dll!System.Linq.Enumerable.ToList<System.Web.Mvc.IValueProvider>(System.Collections.Generic.IEnumerable<System.Web.Mvc.IValueProvider> source) + 0xb5 bytes 
System.Web.Mvc.DLL!System.Web.Mvc.ValueProviderFactoryCollection.GetValueProvider(System.Web.Mvc.ControllerContext controllerContext) + 0x24d bytes 
test.DLL!FailingTest.Test() Line 31 + 0xf9 bytes    C#

我想知道为什么它引发异常并看到的原因：

public static ValidationUtility.UnvalidatedCollections GetUnvalidatedCollections(HttpContext context)
{
    return (ValidationUtility.UnvalidatedCollections) context.Items[_unvalidatedCollectionsKey];
}

所以，当我们依赖时，我们是否回到过去 HttpContext.Current？如何解决？

Answer 1

可以通过访问httpcontext访问忽略它的httpcontext的估值来解决这一问题。

我已经在博客文章中解释了所有内容： ASP.NET MVC3中带有ValueProviderFactories的单位测试动作.

关键是此代码：

public static class ValueProviderFactoresExtensions {
    public static ValueProviderFactoryCollection ReplaceWith<TOriginal>(this ValueProviderFactoryCollection factories, Func<ControllerContext, NameValueCollection> sourceAccessor) {
        var original = factories.FirstOrDefault(x => typeof(TOriginal) == x.GetType());
        if (original != null) {
            var index = factories.IndexOf(original);
            factories[index] = new TestValueProviderFactory(sourceAccessor);
        }
        return factories;
    }

    class TestValueProviderFactory : ValueProviderFactory {
        private readonly Func<ControllerContext, NameValueCollection> sourceAccessor;


        public TestValueProviderFactory(Func<ControllerContext, NameValueCollection> sourceAccessor) {
            this.sourceAccessor = sourceAccessor;
        }


        public override IValueProvider GetValueProvider(ControllerContext controllerContext) {
            return new NameValueCollectionValueProvider(sourceAccessor(controllerContext), CultureInfo.CurrentCulture);
        }
    }        
}

因此可以用作：

ValueProviderFactories.Factories
    .ReplaceWith<FormValueProviderFactory>(ctx => ctx.HttpContext.Request.Form)
    .ReplaceWith<QueryStringValueProviderFactory>(ctx => ctx.HttpContext.Request.QueryString);

实际上非常简单:)

更新: ：如评论中所述，您应该记住：

1. 放 ctx.HttpContext.Request.ContentType 属性达到一些无关的值，否则JSONVALUEPROVIDERFACTORY将引发异常。我更喜欢在那里创建模拟并设置默认值。
2. 更换 HttpFileCollectionValueProviderFactory 可以在绑定过程中使用。
3. 当心项目中可能拥有的其他依赖项。

Answer 2

您不应该从单元测试中调用ValueProviderFactories.FalcroviderFactories.Factries，ModelBinders.binders或任何其他静态访问者。这就是为什么ModelBindingContext.ValueProvider存在 - 这样您就可以提供自己创建的模拟的ivalueprovider，而不是依靠静态默认值（假设MVC管道正在运行）。