def test_elf_3(self):
     self.assertEqual(0, get_presents_by_elf_for_house(3, 1))
     self.assertEqual(0, get_presents_by_elf_for_house(3, 2))
     self.assertEqual(30, get_presents_by_elf_for_house(3, 3))
     self.assertEqual(0, get_presents_by_elf_for_house(3, 4))
 def test_elf_1(self):
     # Should deliver a present to every house.
     for i in range(50):
         self.assertEqual(10, get_presents_by_elf_for_house(1, i))
 def test_elf_2(self):
     # Should deliver a present to every *other* house.
     self.assertEqual(0, get_presents_by_elf_for_house(2, 1))
     self.assertEqual(20, get_presents_by_elf_for_house(2, 2))
     self.assertEqual(0, get_presents_by_elf_for_house(2, 3))
     self.assertEqual(20, get_presents_by_elf_for_house(2, 4))