feat: Better typing (mypy) support for Unset (e.g., using if statements to check type) [#714, #752]. Thanks @taasan & @mcclurem! (#752)

* help mypy figure out that 'Unset' is always falsey

* chore: Regen tests

---------

Co-authored-by: Morgan McClure <morgan_mcclure@apple.com>
Co-authored-by: Dylan Anthony <43723790+dbanty@users.noreply.github.com>
Co-authored-by: Dylan Anthony <dbanty@users.noreply.github.com>

Author: 3 people

end_to_end_tests/golden-record/my_test_api_client/types.py

@@ -1,12 +1,12 @@
 """ Contains some shared types for properties """
 from http import HTTPStatus
-from typing import BinaryIO, Generic, MutableMapping, Optional, Tuple, TypeVar
+from typing import BinaryIO, Generic, Literal, MutableMapping, Optional, Tuple, TypeVar
 
 import attr
 
 
 class Unset:
-    def __bool__(self) -> bool:
+    def __bool__(self) -> Literal[False]:
         return False
 
 

integration-tests/integration_tests/types.py

@@ -1,12 +1,12 @@
 """ Contains some shared types for properties """
 from http import HTTPStatus
-from typing import BinaryIO, Generic, MutableMapping, Optional, Tuple, TypeVar
+from typing import BinaryIO, Generic, Literal, MutableMapping, Optional, Tuple, TypeVar
 
 import attr
 
 
 class Unset:
-    def __bool__(self) -> bool:
+    def __bool__(self) -> Literal[False]:
         return False
 
 

openapi_python_client/templates/types.py.jinja

@@ -1,12 +1,12 @@
 """ Contains some shared types for properties """
 from http import HTTPStatus
-from typing import Any, BinaryIO, Generic, MutableMapping, Optional, Tuple, TypeVar
+from typing import Any, BinaryIO, Generic, MutableMapping, Optional, Tuple, TypeVar, Literal
 
 import attr
 
 
 class Unset:
-    def __bool__(self) -> bool:
+    def __bool__(self) -> Literal[False]:
         return False