using NUnit.Framework;
namespace Pholser {
  [TestFixture]
  public abstract class AbstractTestFixture {
    [TestFixtureSetUp]
    protected virtual void FixtureTearDown() {
    }
    [SetUp]
    protected virtual void SetUp() {
    }
    [TearDown]
    protected virtual void TearDown() {
    }
    [TestFixtureTearDown]
    protected virtual void FixtureTearDown() {
    }
  }
}

The neat part is that since NUnit's attributes are inherited, the subclass doesn't have to be marked with [TestFixture], and if it overrides the fixture methods doesn't have to annotate the overrides (except, of course, with the override keyword...grrr...)

I know it's cool that NUnit doesn't force you to extend a class in order to write tests, but in the interest of removing duplication in your test suite you may find yourself gravitating toward some sort of base fixture class.

One point of interest: NUnit creates one instance of the [TestFixture] to be used by all the [Test] methods on it, unlike JUnit, which gives each testFoo() method its own fixture instance to run on. Hopefully you're writing your tests in such a way that the distinction never matters...