How can I mock Elmah's ErrorSignal routine?

Question

We're using ELMAH for handling errors in our ASP.Net MVC c# application and in our caught exceptions, we're doing something like this:

ErrorSignal.FromCurrentContext().Raise(exception);

but when I try to unit test the caught exceptions, I get this message:

System.ArgumentNullException: Value cannot be null.
Parameter name: context

How can I mock the FromCurrentContext() call? Is there something else I should be doing instead?

FYI... We're currently using Moq and RhinoMocks.

Thanks!

Answer 1

Since the FromCurrentContext() method is a static method you can't simply mock the call to it. You do have two other options.

1. Since FromCurrentContext() internally makes a call to HttpContext.Current you can push a fake context in that. For example:

   SimpleWorkerRequest request = new SimpleWorkerRequest(
       "/blah", @"c:\inetpub\wwwroot\blah", "blah.html", null, new StringWriter());
   
   HttpContext.Current= new HttpContext(request);
   

   With this it should not throw the exception anymore since HttpContext.Current is not null.

2. Create a wrapper class around the call to Raise and just mock out the wrapper class.

   public class ErrorSignaler {
   
       public virtual void SignalFromCurrentContext(Exception e) {
           if (HttpContext.Current != null)
               Elmah.ErrorSignal.FromCurrentContext().Raise(e);
       } 
   }