How to unit test an Action method which returns JsonResult?

Question

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.

Answer 1

I know I'm a bit late on this guys, but I found out why the dynamic solution wasn't working:

JsonResult returns an anonymous object and these are, by default, internal, so they need to be made visible to the tests project.

Open your ASP.NET MVC application project and find AssemblyInfo.cs from folder called Properties. Open AssemblyInfo.cs and add the following line to the end of this file.

[assembly: InternalsVisibleTo("MyProject.Tests")]

Quoted from: http://weblogs.asp.net/gunnarpeipman/archive/2010/07/24/asp-net-mvc-using-dynamic-type-to-test-controller-actions-returning-jsonresult.aspx

I thought it would be nice to have this one for the record. Works like a charm