def test_invalid_nhs_number_detection(self):
"""Check that invalid nhs numbers will be rejected"""
with self.assertRaisesRegex(ValueError, "Number is invalid"):
calculate_check_digit("123456789")
def test_too_long_nhs_numbers_raise_exception(self):
"""Check that if the number is too long, an error is raised"""
with self.assertRaisesRegex(ValueError, "Expecting nine digits"):
calculate_check_digit("1234567890")
def test_providing_something_not_a_number_raises_exception(self):
"""Check that if the string is not numeric, an error is raised"""
with self.assertRaisesRegex(ValueError,
"nhs_number must comprise only digits"):
calculate_check_digit("A")
def test_check_digits_calculate(self):
"""Check that the check digit is correct"""
for number in VALID_NHS_NUMBERS:
self.assertEqual(calculate_check_digit(number[:-1]),
int(number[9]))