Duplicate test using abstract test fixtures

[Charlie Poole]

Reported on nunit-discuss by Victor Kropp:

I've found bug in NUnit 2.5.5 with abstract TestFixtures.
Please find the sample in attached file.

You'll see DuplicateTest 2 times (actually, as much as marked abstract classes in hierarchy)
If non-abstract class is marked as TestFixture test appears only once.

This bug was introduced in version 2.5.3.

Code that reproduces this bug...

using NUnit.Framework;

namespace NUnitBug
{
  [TestFixture]
  public abstract class NUnitDuplicateTestsBaseBaseBase
  {
  }

  [TestFixture]
  public abstract class NUnitDuplicateTestsBaseBase : NUnitDuplicateTestsBaseBaseBase
  {
  }

  public class NUnitDuplicateTests : NUnitDuplicateTestsBaseBase
  {
    [Test]
    public void DuplicateTest()
    {
    }
  }
}

[Charlie Poole (charlie.poole)]

Yes, this is the result of a hack I put in to fix another bug - I feared it would
come back and bite me!

The root cause is that TestFixtureAttribute serves three different purposes:
1) To simpy mark a class as a fixture
2) To provide type arguments for a generic fixture
2) To provide actual arguments for constructing a parameterized fixture

It seemed like a nice idea at the time :-(