def test_none_when_get_nominator_denominator_invalid(self):
     result = Fraction.get_nominator_denominator('a')
     self.assertIsNone(result)
 def test_can_get_nominator_denominator_minus_1_2(self):
     p, q = Fraction.get_nominator_denominator('-1/2')
     result = p == '-1' and q == '2'
     self.assertTrue(result)