WP7 App的HttpWebRequest抛出NullReferenceException

Question

I have the following code to create an HttpWebRequest in my WP7 application. I'm trying to call this code from a Unit Test application which is of type "Silverlight Unit Test Application" with the target framework set to Silverlight 5. I grabbed the WP7.5 Mango Beta test assemblies from Jeff Wilcox's blog:

public void SomeFunction()
{
    Uri uri = new Uri("http://www.google.com");
    HttpWebRequest request = HttpWebRequest.CreateHttp(uri);
    request.Method = "POST";
    ...
}

In the code above, the line that creates the request throws a NullReferenceException . The stack trace doesn't provide anything of value.

Is this happening because I'm using an SL Test Application?

Answer 1

Windows Phone 7.5 uses Silveright 4, not 5, but it's not compatible with the desktop versions of either (unit tests must be run from the WP emulator).

To create a WP test project:

1. Create a Windows Phone Silverlight Application project
2. Add a reference to your actual application project
3. Download and reference the SL Unit Testing assemblies for Mango
4. Add the following code to MainPage in the Loaded event handler:

_

var testPage = UnitTestSystem.CreateTestPage() as IMobileTestPage; 
BackKeyPress += (x, xe) => xe.Cancel = testPage.NavigateBack(); 
(Application.Current.RootVisual as PhoneApplicationFrame).Content = testPage; 

On topic, you might be able to resolve the issue by re-registering the correct handlers:

WebRequest.RegisterPrefix("http://", WebRequestCreator.ClientHttp);
WebRequest.RegisterPrefix("https://", WebRequestCreator.ClientHttp);

However, I'd recommend you just start again.