fix: Injector plugin requires all annotations in the injected function

Author: Daverball

flake8_type_checking/checker.py

@@ -475,6 +475,9 @@ class InjectorMixin:
         def visit(self, node: ast.AST) -> ast.AST:  # noqa: D102
             ...
 
+        def lookup_full_name(self, node: ast.AST) -> str | None:  # noqa: D102
+            ...
+
     def visit_FunctionDef(self, node: FunctionDef) -> None:
         """Remove and map function arguments and returns."""
         super().visit_FunctionDef(node)  # type: ignore[misc]
@@ -487,6 +490,12 @@ def visit_AsyncFunctionDef(self, node: AsyncFunctionDef) -> None:
         if self.injector_enabled:
             self.handle_injector_declaration(node)
 
+    def _has_injected_annotation(self, node: AsyncFunctionDef | FunctionDef) -> bool:
+        return any(
+            isinstance(expr, ast.Subscript) and self.lookup_full_name(expr.value) == 'injector.Inject'
+            for expr in iter_function_annotation_nodes(node)
+        )
+
     def handle_injector_declaration(self, node: AsyncFunctionDef | FunctionDef) -> None:
         """
         Adjust for injector declaration setting.
@@ -496,17 +505,11 @@ def handle_injector_declaration(self, node: AsyncFunctionDef | FunctionDef) -> N
 
         To achieve this, we just visit the annotations to register them as "uses".
         """
-        for path in [node.args.args, node.args.kwonlyargs]:
-            for argument in path:
-                if hasattr(argument, 'annotation') and argument.annotation:
-                    annotation = argument.annotation
-                    if not hasattr(annotation, 'value'):
-                        continue
-                    value = annotation.value
-                    if hasattr(value, 'id') and value.id == 'Inject':
-                        self.visit(argument.annotation)
-                    if hasattr(value, 'attr') and value.attr == 'Inject':
-                        self.visit(argument.annotation)
+        if not self._has_injected_annotation(node):
+            return
+
+        for expr in iter_function_annotation_nodes(node):
+            self.visit(expr)
 
 
 class FastAPIMixin:
@@ -592,6 +595,8 @@ def visit_FunctionDef(self, node: FunctionDef) -> None:
     def visit_AsyncFunctionDef(self, node: AsyncFunctionDef) -> None:
         """Remove and map function arguments and returns."""
         super().visit_AsyncFunctionDef(node)  # type: ignore[misc]
+        if self.in_type_checking_block(node.lineno, node.col_offset):
+            return
         if self.has_singledispatch_decorator(node):
             for expr in iter_function_annotation_nodes(node):
                 self.visit(expr)

tests/test_injector.py

@@ -54,7 +54,7 @@ def __init__(self, service: Inject[Service]) -> None:
 @pytest.mark.parametrize(
     ('enabled', 'expected'),
     [
-        (True, {'4:0 ' + TC002.format(module='other_dependency.OtherDependency')}),
+        (True, set()),
         (
             False,
             {
@@ -65,8 +65,8 @@ def __init__(self, service: Inject[Service]) -> None:
         ),
     ],
 )
-def test_injector_option_only_allows_injected_dependencies(enabled, expected):
-    """Whenever an injector option is enabled, only injected dependencies should be ignored."""
+def test_injector_option_all_annotations_in_function_are_runtime_dependencies(enabled, expected):
+    """Whenever an argument is injected, all the other annotations are runtime required too."""
     example = textwrap.dedent(
         '''
         from injector import Inject
@@ -82,38 +82,20 @@ def __init__(self, service: Inject[Service], other: OtherDependency) -> None:
     assert _get_error(example, error_code_filter='TC002', type_checking_injector_enabled=enabled) == expected
 
 
-@pytest.mark.parametrize(
-    ('enabled', 'expected'),
-    [
-        (True, {'4:0 ' + TC002.format(module='other_dependency.OtherDependency')}),
-        (
-            False,
-            {
-                '2:0 ' + TC002.format(module='injector.Inject'),
-                '3:0 ' + TC002.format(module='services.Service'),
-                '4:0 ' + TC002.format(module='other_dependency.OtherDependency'),
-            },
-        ),
-    ],
-)
-def test_injector_option_only_allows_injector_slices(enabled, expected):
-    """
-    Whenever an injector option is enabled, only injected dependencies should be ignored,
-    not any dependencies with slices.
-    """
+def test_injector_option_require_injections_under_unpack():
+    """Whenever an injector option is enabled, injected dependencies should be ignored, even if unpacked."""
     example = textwrap.dedent(
         """
+        from typing import Unpack
         from injector import Inject
-        from services import Service
-        from other_dependency import OtherDependency
-
+        from services import ServiceKwargs
         class X:
-            def __init__(self, service: Inject[Service], other_deps: list[OtherDependency]) -> None:
+            def __init__(self, service: Inject[Service], **kwargs: Unpack[ServiceKwargs]) -> None:
                 self.service = service
-                self.other_deps = other_deps
+                self.args = args
         """
     )
-    assert _get_error(example, error_code_filter='TC002', type_checking_injector_enabled=enabled) == expected
+    assert _get_error(example, error_code_filter='TC002', type_checking_injector_enabled=True) == set()
 
 
 @pytest.mark.parametrize(