import unittest
from test import support
class TestMROEntry(unittest.TestCase):
def test_mro_entry_signature(self):
tested = []
class B: ...
class C:
def __mro_entries__(self, *args, **kwargs):
tested.extend([args, kwargs])
return (C,)
c = C()
self.assertEqual(tested, [])
class D(B, c): ...
self.assertEqual(tested[0], ((B, c),))
self.assertEqual(tested[1], {})
def test_mro_entry(self):
tested = []
class A: ...
class B: ...
class C:
def __mro_entries__(self, bases):
tested.append(bases)
return (self.__class__,)
c = C()
self.assertEqual(tested, [])
class D(A, c, B): ...
self.assertEqual(tested[-1], (A, c, B))
self.assertEqual(D.__bases__, (A, C, B))
self.assertEqual(D.__orig_bases__, (A, c, B))
self.assertEqual(D.__mro__, (D, A, C, B, object))
d = D()
class E(d): ...
self.assertEqual(tested[-1], (d,))
self.assertEqual(E.__bases__, (D,))
def test_mro_entry_none(self):
tested = []
class A: ...
class B: ...
class C:
def __mro_entries__(self, bases):
tested.append(bases)
return ()
c = C()
self.assertEqual(tested, [])
class D(A, c, B): ...
self.assertEqual(tested[-1], (A, c, B))
self.assertEqual(D.__bases__, (A, B))
self.assertEqual(D.__orig_bases__, (A, c, B))
self.assertEqual(D.__mro__, (D, A, B, object))
class E(c): ...
self.assertEqual(tested[-1], (c,))
self.assertEqual(E.__bases__, (object,))
self.assertEqual(E.__orig_bases__, (c,))
self.assertEqual(E.__mro__, (E, object))
def test_mro_entry_with_builtins(self):
tested = []
class A: ...
class C:
def __mro_entries__(self, bases):
tested.append(bases)
return (dict,)
c = C()
self.assertEqual(tested, [])
class D(A, c): ...
self.assertEqual(tested[-1], (A, c))
self.assertEqual(D.__bases__, (A, dict))
self.assertEqual(D.__orig_bases__, (A, c))
self.assertEqual(D.__mro__, (D, A, dict, object))
def test_mro_entry_with_builtins_2(self):
tested = []
class C:
def __mro_entries__(self, bases):
tested.append(bases)
return (C,)
c = C()
self.assertEqual(tested, [])
class D(c, dict): ...
self.assertEqual(tested[-1], (c, dict))
self.assertEqual(D.__bases__, (C, dict))
self.assertEqual(D.__orig_bases__, (c, dict))
self.assertEqual(D.__mro__, (D, C, dict, object))
def test_mro_entry_errors(self):
class C_too_many:
def __mro_entries__(self, bases, something, other):
return ()
c = C_too_many()
with self.assertRaises(TypeError):
class D(c): ...
class C_too_few:
def __mro_entries__(self):
return ()
d = C_too_few()
with self.assertRaises(TypeError):
class D(d): ...
def test_mro_entry_errors_2(self):
class C_not_callable:
__mro_entries__ = "Surprise!"
c = C_not_callable()
with self.assertRaises(TypeError):
class D(c): ...
class C_not_tuple:
def __mro_entries__(self):
return object
c = C_not_tuple()
with self.assertRaises(TypeError):
class D(c): ...
def test_mro_entry_metaclass(self):
meta_args = []
class Meta(type):
def __new__(mcls, name, bases, ns):
meta_args.extend([mcls, name, bases, ns])
return super().__new__(mcls, name, bases, ns)
class A: ...
class C:
def __mro_entries__(self, bases):
return (A,)
c = C()
class D(c, metaclass=Meta):
x = 1
self.assertEqual(meta_args[0], Meta)
self.assertEqual(meta_args[1], 'D')
self.assertEqual(meta_args[2], (A,))
self.assertEqual(meta_args[3]['x'], 1)
self.assertEqual(D.__bases__, (A,))
self.assertEqual(D.__orig_bases__, (c,))
self.assertEqual(D.__mro__, (D, A, object))
self.assertEqual(D.__class__, Meta)
def test_mro_entry_type_call(self):
# Substitution should _not_ happen in direct type call
class C:
def __mro_entries__(self, bases):
return ()
c = C()
with self.assertRaisesRegex(TypeError,
"MRO entry resolution; "
"use types.new_class()"):
type('Bad', (c,), {})
class TestClassGetitem(unittest.TestCase):
def test_class_getitem(self):
getitem_args = []
class C:
def __class_getitem__(*args, **kwargs):
getitem_args.extend([args, kwargs])
return None
C[int, str]
self.assertEqual(getitem_args[0], (C, (int, str)))
self.assertEqual(getitem_args[1], {})
def test_class_getitem_format(self):
class C:
def __class_getitem__(cls, item):
return f'C[{item.__name__}]'
self.assertEqual(C[int], 'C[int]')
self.assertEqual(C[C], 'C[C]')
def test_class_getitem_inheritance(self):
class C:
def __class_getitem__(cls, item):
return f'{cls.__name__}[{item.__name__}]'
class D(C): ...
self.assertEqual(D[int], 'D[int]')
self.assertEqual(D[D], 'D[D]')
def test_class_getitem_inheritance_2(self):
class C:
def __class_getitem__(cls, item):
return 'Should not see this'
class D(C):
def __class_getitem__(cls, item):
return f'{cls.__name__}[{item.__name__}]'
self.assertEqual(D[int], 'D[int]')
self.assertEqual(D[D], 'D[D]')
def test_class_getitem_classmethod(self):
class C:
@classmethod
def __class_getitem__(cls, item):
return f'{cls.__name__}[{item.__name__}]'
class D(C): ...
self.assertEqual(D[int], 'D[int]')
self.assertEqual(D[D], 'D[D]')
def test_class_getitem_patched(self):
class C:
def __init_subclass__(cls):
def __class_getitem__(cls, item):
return f'{cls.__name__}[{item.__name__}]'
cls.__class_getitem__ = classmethod(__class_getitem__)
class D(C): ...
self.assertEqual(D[int], 'D[int]')
self.assertEqual(D[D], 'D[D]')
def test_class_getitem_with_builtins(self):
class A(dict):
called_with = None
def __class_getitem__(cls, item):
cls.called_with = item
class B(A):
pass
self.assertIs(B.called_with, None)
B[int]
self.assertIs(B.called_with, int)
def test_class_getitem_errors(self):
class C_too_few:
def __class_getitem__(cls):
return None
with self.assertRaises(TypeError):
C_too_few[int]
class C_too_many:
def __class_getitem__(cls, one, two):
return None
with self.assertRaises(TypeError):
C_too_many[int]
def test_class_getitem_errors_2(self):
class C:
def __class_getitem__(cls, item):
return None
with self.assertRaises(TypeError):
C()[int]
class E: ...
e = E()
e.__class_getitem__ = lambda cls, item: 'This will not work'
with self.assertRaises(TypeError):
e[int]
class C_not_callable:
__class_getitem__ = "Surprise!"
with self.assertRaises(TypeError):
C_not_callable[int]
def test_class_getitem_metaclass(self):
class Meta(type):
def __class_getitem__(cls, item):
return f'{cls.__name__}[{item.__name__}]'
self.assertEqual(Meta[int], 'Meta[int]')
def test_class_getitem_with_metaclass(self):
class Meta(type): pass
class C(metaclass=Meta):
def __class_getitem__(cls, item):
return f'{cls.__name__}[{item.__name__}]'
self.assertEqual(C[int], 'C[int]')
def test_class_getitem_metaclass_first(self):
class Meta(type):
def __getitem__(cls, item):
return 'from metaclass'
class C(metaclass=Meta):
def __class_getitem__(cls, item):
return 'from __class_getitem__'
self.assertEqual(C[int], 'from metaclass')
@support.cpython_only
class CAPITest(unittest.TestCase):
def test_c_class(self):
from _testcapi import Generic, GenericAlias
self.assertIsInstance(Generic.__class_getitem__(int), GenericAlias)
IntGeneric = Generic[int]
self.assertIs(type(IntGeneric), GenericAlias)
self.assertEqual(IntGeneric.__mro_entries__(()), (int,))
class C(IntGeneric):
pass
self.assertEqual(C.__bases__, (int,))
self.assertEqual(C.__orig_bases__, (IntGeneric,))
self.assertEqual(C.__mro__, (C, int, object))
if __name__ == "__main__":
unittest.main()