def test_quaternion_vectors(self):
a = Quaternion(0, 0, 0, 1)
b = Matrix((4, 1), (1, 2, 3, 4))
assert a @ b @ a.inverse() == Quaternion(1, 2, 3, 4)
def test_quaternion_product_inverse(self):
a = Quaternion(2, 2, 2, 2)
b = a.inverse()
assert a @ b == Quaternion()
assert b @ a == Quaternion()