@Test
     public void isDog() {
         // create a small dog
    Dog dog = DogFactory.getDog("small");
    Assert.assertEquals("small", dog);

    // create a big dog
    dog = DogFactory.getDog("big");
    Assert.assertEquals("big", dog);

    // create a working dog
    dog = DogFactory.getDog("working");
    Assert.assertEquals("working", dog);
  }