Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

How to unit test ValueProviderFactories in ASP.NET MVC3?

We wanted to upgrade our projects from ASP.NET MVC 2 to 3. Most of our tests succeeded, but there are some that fail on ValueProviderFactories.Factories.GetValueProvider(context).

Here is a simple test class that ilustrates the problem.

[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));
  }
}

Exception "Object reference not set to an instance of an object." is thrown when ValueProviderFactories.Factories.GetValueProvider(context) is called. The stacktrace looks like this:

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#

I wanted to know the reason why it throws the exception and saw:

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

So, are we back in past when we were dependent on HttpContext.Current? How to workaround it?

like image 377
stej Avatar asked Jan 05 '11 11:01

stej


1 Answers

This can easily be solved by prox-ing ValueProviders that access HttpContext to a the one ignoring it.

I have explained everything in my blog post: Unit test actions with ValueProviderFactories in ASP.NET MVC3.

The key is this code:

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);
        }
    }        
}

So it can be used as:

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

It was actually very easy :)

UPDATE: As mentioned in comments you should remember to:

  1. set ctx.HttpContext.Request.ContentType property to some not-null value, otherwise the JsonValueProviderFactory will throw exception. I prefer create a mock and set default value there.
  2. replace the HttpFileCollectionValueProviderFactory as it can be used during binding.
  3. watch out for other dependencies you might have in the project.
like image 89
Dmytrii Nagirniak Avatar answered Oct 18 '22 19:10

Dmytrii Nagirniak