NUnit - cleanup after test failure

Question

We have some NUnit tests that access the database. When one of them fails it can leave database in inconsistent state - which is not an issue, since we rebuild database for

Answer 1

This idea got me interested, so I did a little digging. NUnit doesn't have this ability out of the box, but there is a whole extensibility framework supplied with NUnit. I found this great article about extending NUnit - it was a good starting point. After playing around with it, I came up with the following solution: a method decorated with a custom CleanupOnError attribute will be called if one of the tests in the fixture failed.

Here's how the test looks like:

  [TestFixture]
  public class NUnitAddinTest
  {
    [CleanupOnError]
    public static void CleanupOnError()
    {
      Console.WriteLine("There was an error, cleaning up...");
      // perform cleanup logic
    }

    [Test]
    public void Test1_this_test_passes()
    {
      Console.WriteLine("Hello from Test1");
    }

    [Test]
    public void Test2_this_test_fails()
    {
      throw new Exception("Test2 failed");
    }

    [Test]
    public void Test3_this_test_passes()
    {
      Console.WriteLine("Hello from Test3");
    }
  }

where the attribute is simply:

  [AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
  public sealed class CleanupOnErrorAttribute : Attribute
  {
  }

And here is how it's executed from the addin:

public void RunFinished(TestResult result)
{
  if (result.IsFailure)
  {
    if (_CurrentFixture != null)
    {
      MethodInfo[] methods = Reflect.GetMethodsWithAttribute(_CurrentFixture.FixtureType,
                                                             CleanupAttributeFullName, false);
      if (methods == null || methods.Length == 0)
      {
        return;
      }

      Reflect.InvokeMethod(methods[0], _CurrentFixture);
    }
  }
}

But here's the tricky part: the addin must be placed in the addins directory next to the NUnit runner. Mine was placed next to the NUnit runner in TestDriven.NET directory:

C:\Program Files\TestDriven.NET 2.0\NUnit\addins

(I created the addins directory, it wasn't there)

EDIT Another thing is that the cleanup method needs to be static!

I hacked together a simple addin, you can download the source from my SkyDrive. You will have to add references to nunit.framework.dll, nunit.core.dll and nunit.core.interfaces.dll in the appropriate places.

A few notes: The attribute class can be placed anywhere in your code. I didn't want to place it in the same assembly as the addin itself, because it references two Core NUnit assemblies, so I placed it in a different assembly. Just remember to change the line in the CleanAddin.cs, if you decide to put it anywhere else.

Hope that helps.