"""Unit tests for zero-argument super() & related machinery."""
import sys
import unittest
import warnings
from test.support import check_warnings
class A:
def f(self):
return 'A'
@classmethod
def cm(cls):
return (cls, 'A')
class B(A):
def f(self):
return super().f() + 'B'
@classmethod
def cm(cls):
return (cls, super().cm(), 'B')
class C(A):
def f(self):
return super().f() + 'C'
@classmethod
def cm(cls):
return (cls, super().cm(), 'C')
class D(C, B):
def f(self):
return super().f() + 'D'
def cm(cls):
return (cls, super().cm(), 'D')
class E(D):
pass
class F(E):
f = E.f
class G(A):
pass
class TestSuper(unittest.TestCase):
def tearDown(self):
# This fixes the damage that test_various___class___pathologies does.
nonlocal __class__
__class__ = TestSuper
def test_basics_working(self):
self.assertEqual(D().f(), 'ABCD')
def test_class_getattr_working(self):
self.assertEqual(D.f(D()), 'ABCD')
def test_subclass_no_override_working(self):
self.assertEqual(E().f(), 'ABCD')
self.assertEqual(E.f(E()), 'ABCD')
def test_unbound_method_transfer_working(self):
self.assertEqual(F().f(), 'ABCD')
self.assertEqual(F.f(F()), 'ABCD')
def test_class_methods_still_working(self):
self.assertEqual(A.cm(), (A, 'A'))
self.assertEqual(A().cm(), (A, 'A'))
self.assertEqual(G.cm(), (G, 'A'))
self.assertEqual(G().cm(), (G, 'A'))
def test_super_in_class_methods_working(self):
d = D()
self.assertEqual(d.cm(), (d, (D, (D, (D, 'A'), 'B'), 'C'), 'D'))
e = E()
self.assertEqual(e.cm(), (e, (E, (E, (E, 'A'), 'B'), 'C'), 'D'))
def test_super_with_closure(self):
# Issue4360: super() did not work in a function that
# contains a closure
class E(A):
def f(self):
def nested():
self
return super().f() + 'E'
self.assertEqual(E().f(), 'AE')
def test_various___class___pathologies(self):
# See issue #12370
class X(A):
def f(self):
return super().f()
__class__ = 413
x = X()
self.assertEqual(x.f(), 'A')
self.assertEqual(x.__class__, 413)
class X:
x = __class__
def f():
__class__
self.assertIs(X.x, type(self))
with self.assertRaises(NameError) as e:
exec("""class X:
__class__
def f():
__class__""", globals(), {})
self.assertIs(type(e.exception), NameError) # Not UnboundLocalError
class X:
global __class__
__class__ = 42
def f():
__class__
self.assertEqual(globals()["__class__"], 42)
del globals()["__class__"]
self.assertNotIn("__class__", X.__dict__)
class X:
nonlocal __class__
__class__ = 42
def f():
__class__
self.assertEqual(__class__, 42)
def test___class___instancemethod(self):
# See issue #14857
class X:
def f(self):
return __class__
self.assertIs(X().f(), X)
def test___class___classmethod(self):
# See issue #14857
class X:
@classmethod
def f(cls):
return __class__
self.assertIs(X.f(), X)
def test___class___staticmethod(self):
# See issue #14857
class X:
@staticmethod
def f():
return __class__
self.assertIs(X.f(), X)
def test___class___new(self):
# See issue #23722
# Ensure zero-arg super() works as soon as type.__new__() is completed
test_class = None
class Meta(type):
def __new__(cls, name, bases, namespace):
nonlocal test_class
self = super().__new__(cls, name, bases, namespace)
test_class = self.f()
return self
class A(metaclass=Meta):
@staticmethod
def f():
return __class__
self.assertIs(test_class, A)
def test___class___delayed(self):
# See issue #23722
test_namespace = None
class Meta(type):
def __new__(cls, name, bases, namespace):
nonlocal test_namespace
test_namespace = namespace
return None
# This case shouldn't trigger the __classcell__ deprecation warning
with check_warnings() as w:
warnings.simplefilter("always", DeprecationWarning)
class A(metaclass=Meta):
@staticmethod
def f():
return __class__
self.assertEqual(w.warnings, [])
self.assertIs(A, None)
B = type("B", (), test_namespace)
self.assertIs(B.f(), B)
def test___class___mro(self):
# See issue #23722
test_class = None
class Meta(type):
def mro(self):
# self.f() doesn't work yet...
self.__dict__["f"]()
return super().mro()
class A(metaclass=Meta):
def f():
nonlocal test_class
test_class = __class__
self.assertIs(test_class, A)
def test___classcell___expected_behaviour(self):
# See issue #23722
class Meta(type):
def __new__(cls, name, bases, namespace):
nonlocal namespace_snapshot
namespace_snapshot = namespace.copy()
return super().__new__(cls, name, bases, namespace)
# __classcell__ is injected into the class namespace by the compiler
# when at least one method needs it, and should be omitted otherwise
namespace_snapshot = None
class WithoutClassRef(metaclass=Meta):
pass
self.assertNotIn("__classcell__", namespace_snapshot)
# With zero-arg super() or an explicit __class__ reference,
# __classcell__ is the exact cell reference to be populated by
# type.__new__
namespace_snapshot = None
class WithClassRef(metaclass=Meta):
def f(self):
return __class__
class_cell = namespace_snapshot["__classcell__"]
method_closure = WithClassRef.f.__closure__
self.assertEqual(len(method_closure), 1)
self.assertIs(class_cell, method_closure[0])
# Ensure the cell reference *doesn't* get turned into an attribute
with self.assertRaises(AttributeError):
WithClassRef.__classcell__
def test___classcell___missing(self):
# See issue #23722
# Some metaclasses may not pass the original namespace to type.__new__
# We test that case here by forcibly deleting __classcell__
class Meta(type):
def __new__(cls, name, bases, namespace):
namespace.pop('__classcell__', None)
return super().__new__(cls, name, bases, namespace)
# The default case should continue to work without any warnings
with check_warnings() as w:
warnings.simplefilter("always", DeprecationWarning)
class WithoutClassRef(metaclass=Meta):
pass
self.assertEqual(w.warnings, [])
# With zero-arg super() or an explicit __class__ reference, we expect
# __build_class__ to emit a DeprecationWarning complaining that
# __class__ was not set, and asking if __classcell__ was propagated
# to type.__new__.
# In Python 3.7, that warning will become a RuntimeError.
expected_warning = (
'__class__ not set.*__classcell__ propagated',
DeprecationWarning
)
with check_warnings(expected_warning):
warnings.simplefilter("always", DeprecationWarning)
class WithClassRef(metaclass=Meta):
def f(self):
return __class__
# Check __class__ still gets set despite the warning
self.assertIs(WithClassRef().f(), WithClassRef)
# Check the warning is turned into an error as expected
with warnings.catch_warnings():
warnings.simplefilter("error", DeprecationWarning)
with self.assertRaises(DeprecationWarning):
class WithClassRef(metaclass=Meta):
def f(self):
return __class__
def test___classcell___overwrite(self):
# See issue #23722
# Overwriting __classcell__ with nonsense is explicitly prohibited
class Meta(type):
def __new__(cls, name, bases, namespace, cell):
namespace['__classcell__'] = cell
return super().__new__(cls, name, bases, namespace)
for bad_cell in (None, 0, "", object()):
with self.subTest(bad_cell=bad_cell):
with self.assertRaises(TypeError):
class A(metaclass=Meta, cell=bad_cell):
pass
def test___classcell___wrong_cell(self):
# See issue #23722
# Pointing the cell reference at the wrong class is also prohibited
class Meta(type):
def __new__(cls, name, bases, namespace):
cls = super().__new__(cls, name, bases, namespace)
B = type("B", (), namespace)
return cls
with self.assertRaises(TypeError):
class A(metaclass=Meta):
def f(self):
return __class__
def test_obscure_super_errors(self):
def f():
super()
self.assertRaises(RuntimeError, f)
def f(x):
del x
super()
self.assertRaises(RuntimeError, f, None)
class X:
def f(x):
nonlocal __class__
del __class__
super()
self.assertRaises(RuntimeError, X().f)
def test_cell_as_self(self):
class X:
def meth(self):
super()
def f():
k = X()
def g():
return k
return g
c = f().__closure__[0]
self.assertRaises(TypeError, X.meth, c)
def test_super_init_leaks(self):
# Issue #26718: super.__init__ leaked memory if called multiple times.
# This will be caught by regrtest.py -R if this leak.
# NOTE: Despite the use in the test a direct call of super.__init__
# is not endorsed.
sp = super(float, 1.0)
for i in range(1000):
super.__init__(sp, int, i)
if __name__ == "__main__":
unittest.main()