def test_weight_with_empty_string(self): self.assertFalse(Donor.is_valid_weight(''))
def test_weight_with_zero(self): self.assertFalse(Donor.is_valid_weight('0'))
def test_weight_with_letters(self): self.assertFalse(Donor.is_valid_weight('abc'))
def test_weight_with_valid_string(self): self.assertTrue(Donor.is_valid_weight('50'))