fix coverage and make typing-extensions a required dependency

pydantic/fields.py

@@ -343,7 +343,7 @@ def _get_field_info(
         field_info_from_config = config.get_field_info(field_name)
 
         field_info = None
-        if get_origin(annotation) is Annotated:
+        if Annotated and get_origin(annotation) is Annotated:
             field_infos = [arg for arg in get_args(annotation)[1:] if isinstance(arg, FieldInfo)]
             if len(field_infos) > 1:
                 raise ValueError(f'cannot specify multiple `Annotated` `Field`s for {field_name!r}')
@@ -497,7 +497,7 @@ def _type_analysis(self) -> None:  # noqa: C901 (ignore complexity)
             if isinstance(self.type_, type) and isinstance(None, self.type_):
                 self.allow_none = True
             return
-        if origin is Annotated:
+        if Annotated and origin is Annotated:
             self.type_ = get_args(self.type_)[0]
             self._type_analysis()
             return

pydantic/schema.py

@@ -944,7 +944,7 @@ def go(type_: Any) -> Type[Any]:
                 # forward refs cause infinite recursion below
                 return type_
 
-            if origin is Annotated:
+            if Annotated and origin is Annotated:
                 return go(args[0])
             if origin is Union:
                 return Union[tuple(go(a) for a in args)]  # type: ignore

pydantic/typing.py

@@ -90,21 +90,7 @@ def evaluate_forwardref(type_: ForwardRef, globalns: Any, localns: Any) -> Any:
         try:
             from typing_extensions import Annotated
         except ImportError:
-            # Create mock Annotated values distinct from `None`, which is a valid `get_origin`
-            # return value.
-            class _FalseMeta(type):
-                # Allow short circuiting with "Annotated[...] if Annotated else None".
-                def __bool__(cls):
-                    return False
-
-                # Give a nice suggestion for unguarded use
-                def __getitem__(cls, key):
-                    raise RuntimeError(
-                        'Annotated is not supported in this python version, please `pip install typing-extensions`.'
-                    )
-
-            class Annotated(metaclass=_FalseMeta):
-                pass
+            Annotated = None
 
 
 # Annotated[...] is implemented by returning an instance of one of these classes, depending on

tests/test_annotated.py

@@ -7,8 +7,9 @@
 from pydantic.fields import Undefined
 from pydantic.typing import Annotated
 
+pytestmark = pytest.mark.skipif(not Annotated, reason='typing_extensions not installed')
+
 
-@pytest.mark.skipif(not Annotated, reason='typing_extensions not installed')
 @pytest.mark.parametrize(
     ['hint_fn', 'value'],
     [
@@ -55,7 +56,6 @@ class M(BaseModel):
         assert get_type_hints(M)['x'] == hint
 
 
-@pytest.mark.skipif(not Annotated, reason='typing_extensions not installed')
 @pytest.mark.parametrize(
     ['hint_fn', 'value', 'subclass_ctx'],
     [
@@ -93,7 +93,6 @@ class M(BaseModel):
             x: hint = value
 
 
-@pytest.mark.skipif(not Annotated, reason='typing_extensions not installed')
 @pytest.mark.parametrize(
     ['hint_fn', 'value', 'empty_init_ctx'],
     [
@@ -121,7 +120,6 @@ class M(BaseModel):
         assert M().x == 5
 
 
-@pytest.mark.skipif(not Annotated, reason='typing_extensions not installed')
 def test_field_reuse():
     field = Field(description='Long description')