Method test_protocols_isinstance

Lib/test/test_typing.py:3464–3524

(self)

            issubclass(Eggs, Spam)

    def test_protocols_isinstance(self):
        T = TypeVar('T')

        @runtime_checkable
        class P(Protocol):
            def meth(x): ...

        @runtime_checkable
        class PG(Protocol[T]):
            def meth(x): ...

        @runtime_checkable
        class WeirdProto(Protocol):
            meth = str.maketrans

        @runtime_checkable
        class WeirdProto2(Protocol):
            meth = lambda *args, **kwargs: None

        class CustomCallable:
            def __call__(self, *args, **kwargs):
                pass

        @runtime_checkable
        class WeirderProto(Protocol):
            meth = CustomCallable()

        class BadP(Protocol):
            def meth(x): ...

        class BadPG(Protocol[T]):
            def meth(x): ...

        class C:
            def meth(x): ...

        class C2:
            def __init__(self):
                self.meth = lambda: None

        for klass in C, C2:
            for proto in P, PG, WeirdProto, WeirdProto2, WeirderProto:
                with self.subTest(klass=klass.__name__, proto=proto.__name__):
                    self.assertIsInstance(klass(), proto)

        no_subscripted_generics = "Subscripted generics cannot be used with class and instance checks"

        with self.assertRaisesRegex(TypeError, no_subscripted_generics):
            isinstance(C(), PG[T])
        with self.assertRaisesRegex(TypeError, no_subscripted_generics):
            isinstance(C(), PG[C])

        only_runtime_checkable_msg = (
            "Instance and class checks can only be used "
            "with @runtime_checkable protocols"
        )

        with self.assertRaisesRegex(TypeError, only_runtime_checkable_msg):