'Test media_image_url property.'

def test_media_image_url(self):

    TEST_URL = 'test_url'
    config = self.config_children_only
    universal.validate_config(config)
    ump = universal.UniversalMediaPlayer(self.hass, **config)
    ump.entity_id = media_player.ENTITY_ID_FORMAT.format(config['name'])
    run_coroutine_threadsafe(ump.async_update(), self.hass.loop).result()
    self.assertEqual(None, ump.media_image_url)
    self.mock_mp_1._state = STATE_PLAYING
    self.mock_mp_1._media_image_url = TEST_URL
    self.mock_mp_1.schedule_update_ha_state()
    self.hass.block_till_done()
    run_coroutine_threadsafe(ump.async_update(), self.hass.loop).result()
    self.assertEqual(self.mock_mp_1.entity_picture, ump.entity_picture)
