How to unit test an Action method which returns JsonResult?

If I have a controller like this:

[HttpPost]
public JsonResult FindStuff(string query) 
{
   var results = _repo.GetStuff(query);
   var jsonResult = results.Select(x => new
   {
      id = x.Id,
      name = x.Foo,
      type = x.Bar
   }).ToList();

   return Json(jsonResult);
}

Basically, I grab stuff from my repository, then project it into a List<T> of anonymous types.

How can I unit-test it?

System.Web.Mvc.JsonResult has a property called Data, but it's of type object, as we expected.

So does that mean if I want to test that the JSON object has the properties I expect ("id", "name", "type"), I have to use reflection?

EDIT:

Here's my test:

// Arrange.
const string autoCompleteQuery = "soho";

// Act.
var actionResult = _controller.FindLocations(autoCompleteQuery);

// Assert.
Assert.IsNotNull(actionResult, "No ActionResult returned from action method.");
dynamic jsonCollection = actionResult.Data;
foreach (dynamic json in jsonCollection)
{
   Assert.IsNotNull(json.id, 
       "JSON record does not contain \"id\" required property.");
   Assert.IsNotNull(json.name, 
       "JSON record does not contain \"name\" required property.");
   Assert.IsNotNull(json.type, 
       "JSON record does not contain \"type\" required property.");
}

But I get a runtime error in the loop, stating "object does not contain a definition for id".

When I breakpoint, actionResult.Data is defined as a List<T> of anonymous types, so I figure if I enumerate through these, I can check the properties. Inside the loop, the object does have a property called "id" - so not sure what the issue is.