Test cases in inner classes with JUnit

You should annontate your class with @RunWith(Enclosed.class), and like others said, declare the inner classes as static:

@RunWith(Enclosed.class)
public class DogTests
  {
  public static class BarkTests
  {
    @Test
    public void quietBark_IsAtLeastAudible() { }

    @Test
    public void loudBark_ScaresAveragePerson() { }
  }

  public static class EatTests
  {
    @Test
    public void normalFood_IsEaten() { }

    @Test
    public void badFood_ThrowsFit() { }
  }
}