'Test get_changed_since.'

def test_get_changed_since(self):

    point1 = dt_util.utcnow()
    point2 = (point1 + timedelta(seconds=5))
    point3 = (point2 + timedelta(seconds=5))
    with patch('homeassistant.core.dt_util.utcnow', return_value=point1):
        self.hass.states.set('light.test', 'on')
        state1 = self.hass.states.get('light.test')
    with patch('homeassistant.core.dt_util.utcnow', return_value=point2):
        self.hass.states.set('light.test2', 'on')
        state2 = self.hass.states.get('light.test2')
    with patch('homeassistant.core.dt_util.utcnow', return_value=point3):
        self.hass.states.set('light.test3', 'on')
        state3 = self.hass.states.get('light.test3')
    self.assertEqual([state2, state3], state.get_changed_since([state1, state2, state3], point2))
