def test_patch_revert():
class a:
pass
raises(AttributeError, "patch(a, 'i', 42)")
a.i = 42
patch(a, 'i', 23)
assert a.i == 23
revert(a, 'i')
assert a.i == 42
def test_double_patch():
class a:
i = 42
assert patch(a, 'i', 2) == 42
assert patch(a, 'i', 3) == 2
assert a.i == 3
assert revert(a, 'i') == 3
assert a.i == 2
assert revert(a, 'i') == 2
assert a.i == 42