def test_is_free(self):
x = self.x
y = self.y
zero = self.poly_ring.zero()
free = SingularModule([[x, zero, zero], [zero, y, zero],
[zero, zero, x**2]])
self.assertTrue(free.is_free())
def test_is_free_not(self):
x = self.x
y = self.y
sm1 = SingularModule([[x, x, x], [y, y, y]])
self.assertFalse(sm1.is_free())
