An action method in my ASP.NET MVC2 application returns a JsonResult object and in my unit test I would like to check that the returned JSON object indeed contains the expected values.

I tried this:

1. dynamic json = ((JsonResult)myActionResult).Data;
2. Assert.AreEqual(JsonMessagesHelper.ErrorLevel.ERROR.ToString(), json.ErrorLevel);

But I get a RuntimeBinderException "'object' does not contain a definition for 'ErrorLevel'".

However, when I place a breakpoint on line 2 and inspect the json dynamic variable (see picture below), it obviously does contain the ErrorLevel string and it has the expected value, so if the runtime binder wasn't playing funny the test would pass.

What am I not getting? What am I doing wrong and how can I fix this? How can I make the assertion pass?