_infer_injected_bindings: Don't strip NoneType from function bindings

Author: AvlWx2014

injector/__init__.py

@@ -1253,9 +1253,8 @@ def _is_injection_annotation(annotation: Any) -> bool:
         if only_explicit_bindings and _inject_marker not in metadata or _noinject_marker in metadata:
             del bindings[k]
         elif _is_specialization(v, Union) or _is_new_union_type(v):
-            # We don't treat Optional parameters in any special way at the moment.
             union_members = v.__args__
-            new_members = tuple(set(union_members) - {type(None)})
+            new_members = tuple(set(union_members))
             # mypy stared complaining about this line for some reason:
             #     error: Variable "new_members" is not valid as a type
             new_union = Union[new_members]  # type: ignore

injector_test.py

@@ -1674,8 +1674,7 @@ def function11(a: int) -> 'InvalidForwardReference':
     assert get_bindings(function11) == {'a': int}
 
 
-    # This will not inject `None` even if there is a provider configured to provide
-    # str | None elsewhere in the graph because `None` is stripped in
+    # This should correctly resolve str | None
     @inject
     def function12(a: str | None):
         pass
@@ -1690,7 +1689,7 @@ def test_get_bindings_for_pep_604():
     def function1(a: int | None) -> None:
         pass
 
-    assert get_bindings(function1) == {'a': int}
+    assert get_bindings(function1) == {'a': Union[int, None]}
 
     @inject
     def function1(a: int | str) -> None: