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Merged
agronholm merged 2 commits into from
May 8, 2022
Merged

Handles type checks for Type[Protocol] #251

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16dd3c4
Handles type checks for Type[Protocol]
williamlw999-fb Apr 21, 2022
bd2982b
Update src/typeguard/_checkers.py
agronholm May 8, 2022
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10 changes: 9 additions & 1 deletion src/typeguard/_checkers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -376,7 +376,9 @@ def check_class(
return

expected_class = args[0]
if isinstance(expected_class, TypeVar):
if getattr(expected_class, "_is_protocol", False):
check_protocol(value, expected_class, (), memo)
elif isinstance(expected_class, TypeVar):
check_typevar(value, expected_class, (), memo, subclass_check=True)
elif get_origin(expected_class) is Union:
errors: Dict[str, TypeCheckError] = {}
Expand Down Expand Up @@ -501,6 +503,12 @@ def check_protocol(
raise TypeCheckError(
f"is not compatible with the {origin_type.__qualname__} protocol"
)
else:
warnings.warn(
f"Typeguard cannot check the {origin_type.__qualname__} protocol because "
f"it is a non-runtime protocol. If you would like to type check this "
f"protocol, please use @typing.runtime_checkable"
)


def check_byteslike(
Expand Down
35 changes: 30 additions & 5 deletions tests/test_checkers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -681,24 +681,46 @@ def test_text_real_file(self, tmp_path: Path):


class TestProtocol:
@pytest.mark.parametrize("protocol_cls", [RuntimeProtocol, StaticProtocol])
def test_protocol(self, protocol_cls):
def test_protocol(self):
class Foo:
member = 1

def meth(self) -> None:
pass

check_type(Foo(), protocol_cls)
check_type(Foo(), RuntimeProtocol)
check_type(Foo, Type[RuntimeProtocol])

def test_non_method_members(self):
def test_protocol_warns_on_static(self):
class Foo:
member = 1

def meth(self) -> None:
pass

check_type(Foo(), RuntimeProtocol)
with pytest.warns(
UserWarning, match=r"Typeguard cannot check the StaticProtocol protocol.*"
):
check_type(Foo(), StaticProtocol)

with pytest.warns(
UserWarning, match=r"Typeguard cannot check the StaticProtocol protocol.*"
):
check_type(Foo, Type[StaticProtocol])

def test_fail_non_method_members(self):
class Foo:
val = 1

def meth(self) -> None:
pass

pytest.raises(TypeCheckError, check_type, Foo(), RuntimeProtocol).match(
"value is not compatible with the RuntimeProtocol protocol"
)
pytest.raises(TypeCheckError, check_type, Foo, Type[RuntimeProtocol]).match(
"value is not compatible with the RuntimeProtocol protocol"
)

def test_fail(self):
class Foo:
Expand All @@ -708,6 +730,9 @@ def meth2(self) -> None:
pytest.raises(TypeCheckError, check_type, Foo(), RuntimeProtocol).match(
"value is not compatible with the RuntimeProtocol protocol"
)
pytest.raises(TypeCheckError, check_type, Foo, Type[RuntimeProtocol]).match(
"value is not compatible with the RuntimeProtocol protocol"
)


class TestMock:
Expand Down