NullRepository implements Repository { @Override public RepositoryDTO fetchInstallableApplications() { return new RepositoryDTO.Builder().build(); }  @Override RepositoryDTO fetchInstallableApplications(); @Override boolean equals(Object o); @Override int hashCode();  }
@Test public void testNullRepositoryTest() { assertEquals(new RepositoryDTO.Builder().build(), new NullRepository().fetchInstallableApplications()); }