Building unit tests for MVC2 AsyncControllers

Question

I\'m considering re-rewriting some of my MVC controllers to be async controllers. I have working unit tests for these controllers, but I\'m trying to understand how to maintain

Answer 1

As with any async code, unit testing needs to be aware of thread signalling. .NET includes a type called AutoResetEvent which can block the test thread until an async operation has been completed:

public class MyAsyncController : Controller
{
  public void TransactionAsync()
  {
    AsyncManager.Parameters["result"] = "result";
  }

  public ContentResult TransactionCompleted(string result)
  {
    return Content(result);
  }
}

[TestFixture]
public class MyAsyncControllerTests
{
  #region Fields
  private AutoResetEvent trigger;
  private MyAsyncController controller;
  #endregion

  #region Tests
  [Test]
  public void TestTransactionAsync()
  {
    controller = new MyAsyncController();
    trigger = new AutoResetEvent(false);

    // When the async manager has finished processing an async operation, trigger our AutoResetEvent to proceed.
    controller.AsyncManager.Finished += (sender, ev) => trigger.Set();

    controller.TransactionAsync();
    trigger.WaitOne()

    // Continue with asserts
  }
  #endregion
}

Hope that helps :)