def test_pgcd_negative_numbers():
assert audio.pgcd(-21, -7) == audio.pgcd(-7, -21) == -7
def test_pgcd_with_a_null_number():
assert audio.pgcd(0, 7) == audio.pgcd(7, 0) == 7
assert audio.pgcd(0, 8) == audio.pgcd(8, 0) == 8
def test_pgcd_with_a_negative_number():
assert audio.pgcd(-32, 8) == 8
assert audio.pgcd(8, -32) == -8
def test_pgcd_odd_numbers():
assert audio.pgcd(35, 91) == audio.pgcd(91, 35) == 7
def test_pgcd_even_numbers():
assert audio.pgcd(28, 94) == audio.pgcd(94, 28) == 2
def test_pgcd_odd_and_even_numbers_with_odd_bigger():
assert audio.pgcd(63, 28) == audio.pgcd(28, 63) == 7
def test_pgcd_odd_and_even_numbers_with_even_bigger():
assert audio.pgcd(21, 56) == audio.pgcd(56, 21) == 7
def test_pgcd_a_and_b_equals():
assert audio.pgcd(1, 1) == 1