@Test
public void testCreateTailSkin() {

    CONNECTOR.setType(null);
    assertNull(skinFactory.createTailSkin(null));
    assertTrue(skinFactory.createTailSkin(CONNECTOR) instanceof DefaultTailSkin);
    CONNECTOR.setType(CONNECTOR_TYPE);
    assertTrue(skinFactory.createTailSkin(CONNECTOR) instanceof DefaultTailSkin);
    CONNECTOR.setType(CONNECTOR_TYPE);
    skinFactory.setTailSkin(CONNECTOR_TYPE, CustomTailSkin.class);
    assertTrue(skinFactory.createTailSkin(CONNECTOR) instanceof CustomTailSkin);
}