@SuppressWarnings("unchecked")
@Test
public void testIsEmptyTrue() {

    Enumeration<String> keys = createMock(Enumeration.class);
    expect(extractor.getKeys()).andReturn(keys);
    expect(keys.hasMoreElements()).andReturn(false);
    replay(extractor, keys);
    assertTrue(entrySet.isEmpty());
    verify(extractor, keys);
}