How to unit test an ActionResult that returns a ContentResult?

Question

I want to unit test the following ASP.NET MVC controller Index action. What do I replace the actual parameter in the assert below (stubbed with ?).

using System.Web.Mvc;
namespace MvcApplication1.Controllers
{
    public class StatusController : Controller
    {
        public ActionResult Index()
        {
            return Content("Hello World!");
        }
    }
}


[TestMethod]
public void TestMethod1()
{
    // Arrange
    var controller = CreateStatusController();

    // Act
    var result = controller.Index();

    // Assert
    Assert.AreEqual( "Hello World!.", ? );
}

score 22 · Accepted Answer · answered Feb 25 '10 at 16:36

use the "as" operator to make a nullable cast. Then simply check for a null result

[TestMethod]
public void TestMethod1()
{
    // Arrange
    var controller = CreateStatusController();

    // Act
    var result = controller.Index() as ContentResult;

    // Assert
    Assert.NotNull(result);
    Assert.AreEqual( "Hello World!.", result.Content);
}

score 11 · Answer 2 · answered Feb 25 '10 at 19:44

11

I like creating assertion helpers for this sort of thing. For instance, you might do something like:

public static class AssertActionResult {
    public static void IsContentResult(ActionResult result, string contentToMatch) {
        var contentResult = result as ContentResult;
        Assert.NotNull(contentResult);
        Assert.AreEqual(contentToMatch, contentResult.Content);        
    }
}

You'd then call this like:

[TestMethod]
public void TestMethod1()
{
    var controller = CreateStatusController();
    var result = controller.Index();

    AssertActionResult.IsContentResult(result, "Hello World!");    
}

I think this makes the tests so much easier to read and write.

answered Feb 25 '10 at 19:44

Seth Petry-Johnson

11,845
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That's a great idea Seth. I have quite a few of the ContentResult unit tests to code so this will help on trying to keep to the DRY philosophy . – Nicholas Murray Feb 25 '10 at 20:21
@Nicholas: Glad you found it helpful. Other helpers I have are `AssertActionResult.IsRedirectTo(result, url)` and `AssertActionResult.IsViewResult(result, viewName)`. – Seth Petry-Johnson Feb 25 '10 at 20:25

score 4 · Answer 3 · edited Mar 14 '13 at 13:56

You cant test that the result is not null, that you receive a ContentResult and compare the values:

[TestMethod]
public void TestMethod1()
{
    // Arrange
    var controller = CreateStatusController();

    // Act
    var result = controller.Index();

    // Assert
    Assert.NotNull(result);
    Assert.IsAssignableFrom(typeof(ContentResult), result);
    Assert.AreEqual( "Hello World!.", result.Content);
}

I apoligize if the Nunit asserts aren't welformed, but look at it as pseudo-code :)

How to unit test an ActionResult that returns a ContentResult?

3 Answers3

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