### Question:
DiskUserDataStore implements UserDataStore { @Override public Observable<List<UserEntity>> userEntityList() { throw new UnsupportedOperationException("Operation is not available!!!"); } DiskUserDataStore(UserCache userCache); @Override Observable<List<UserEntity>> userEntityList(); @Override Observable<UserEntity> userEntityDetails(final int userId);  }### Answer:
@Test public void testGetUserEntityListUnsupported() { expectedException.expect(UnsupportedOperationException.class); diskUserDataStore.userEntityList(); }