def test_shadows_can_cover_other_shadows(self):
""" A Shadow X covers another Shadow Y if:
- X starts before or at the same place as Y
- X ends after or at the same place as Y
"""
bigger = Shadow(0, 0.7)
smaller = Shadow(0.2, 0.6)
also_small = Shadow(0.2, 0.3)
self.assertTrue(bigger.covers(smaller))
self.assertFalse(smaller.covers(bigger))
self.assertTrue(smaller.covers(also_small))
