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         


        

Answer 1

I'm a bit late to the party, but I created a little wrapper that lets me then use dynamic properties. As of this answer I've got this working on ASP.NET Core 1.0 RC2, but I believe if you replace resultObject.Value with resultObject.Data it should work for non-core versions.

public class JsonResultDynamicWrapper : DynamicObject
{
    private readonly object _resultObject;

    public JsonResultDynamicWrapper([NotNull] JsonResult resultObject)
    {
        if (resultObject == null) throw new ArgumentNullException(nameof(resultObject));
        _resultObject = resultObject.Value;
    }

    public override bool TryGetMember(GetMemberBinder binder, out object result)
    {
        if (string.IsNullOrEmpty(binder.Name))
        {
            result = null;
            return false;
        }

        PropertyInfo property = _resultObject.GetType().GetProperty(binder.Name);

        if (property == null)
        {
            result = null;
            return false;
        }

        result = property.GetValue(_resultObject, null);
        return true;
    }
}

Usage, assuming the following controller:

public class FooController : Controller
{
    public IActionResult Get()
    {
        return Json(new {Bar = "Bar", Baz = "Baz"});
    }
}

The test (xUnit):

// Arrange
var controller = new FoosController();

// Act
var result = await controller.Get();

// Assert
var resultObject = Assert.IsType(result);
dynamic resultData = new JsonResultDynamicWrapper(resultObject);
Assert.Equal("Bar", resultData.Bar);
Assert.Equal("Baz", resultData.Baz);