def test_gcd_consistency(a ,b):
d = gcd(a, b)
if a == b == 0:
assert (a == b == d == 0)
elif a == 0:
assert (a == 0 and d == b)
elif b == 0:
assert (b == 0 and d == a)
else:
assert (a % d == 0 and b % d == 0)
def test_gcd_known(a, b, d):
assert gcd(a, b) == d
def test_gcd_commutative(a, b):
assert gcd(a, b) == gcd(b, a)
def test_gcd_ret_type(a, b):
assert_is_integer(gcd(a, b))