Improve the handling of stringified annotations in _takes_container

conftest.py

@@ -2,7 +2,6 @@
 #
 # SPDX-License-Identifier: MIT
 
-
 from doctest import ELLIPSIS
 
 import pytest

src/svcs/_core.py

@@ -403,9 +403,18 @@ def _takes_container(factory: Callable) -> bool:
     Return True if *factory* takes a svcs.Container as its first argument.
     """
     try:
-        sig = inspect.signature(factory)
+        # Provide the locals so that `eval_str` will work even if the user places the `Container`
+        # under a `if TYPE_CHECKING` block
+        sig = inspect.signature(
+            factory, locals={"Container": Container}, eval_str=True
+        )
     except Exception:  # noqa: BLE001
-        return False
+        # Retry without `eval_str` since if the annotation is "svcs.Container" the eval
+        # will fail due to it not finding the `svcs` module
+        try:
+            sig = inspect.signature(factory)
+        except Exception:  # noqa: BLE001
+            return False
 
     if not sig.parameters:
         return False
@@ -415,13 +424,13 @@ def _takes_container(factory: Callable) -> bool:
         raise TypeError(msg)
 
     ((name, p),) = tuple(sig.parameters.items())
-    if name == "svcs_container":
-        return True
-
-    if (annot := p.annotation) is Container or annot == "svcs.Container":
-        return True
 
-    return False
+    return (
+        name == "svcs_container"
+        or p.annotation is Container
+        or p.annotation == "svcs.Container"
+        or p.annotation == "Container"
+    )
 
 
 T1 = TypeVar("T1")

tests/test_registry.py

@@ -4,8 +4,10 @@
 
 import contextlib
 import gc
+import importlib.util
 import inspect
 import logging
+import sys
 
 from unittest.mock import AsyncMock, Mock
 
@@ -24,6 +26,23 @@
 )
 
 
+@pytest.fixture(name="create_module")
+def _create_module(tmp_path):
+    def wrapper(source):
+        module_name = "_svcs_testing_tmp_module"
+        module_path = tmp_path / f"{module_name}.py"
+        module_path.write_text(source)
+
+        spec = importlib.util.spec_from_file_location(module_name, module_path)
+        module = importlib.util.module_from_spec(spec)
+        sys.modules[module_name] = module
+        spec.loader.exec_module(module)
+
+        return module
+
+    return wrapper
+
+
 class TestRegistry:
     def test_repr_empty(self, registry):
         """
@@ -316,6 +335,51 @@ def diff_name():
     ...
 
 
+takes_containers_annotation_string_modules = (
+    """
+from __future__ import annotations
+
+from svcs import Container
+
+def factory(container: Container) -> int:
+    ...
+    """,
+    """
+from __future__ import annotations
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from svcs import Container
+
+def factory(container: Container) -> int:
+    ...
+    """,
+    """
+def factory(container: "svcs.Container") -> int:
+    ...
+    """,
+    """
+from __future__ import annotations
+
+import svcs
+
+def factory(container: svcs.Container) -> int:
+    ...
+
+    """,
+    """
+from __future__ import annotations
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    import svcs
+
+def factory(container: svcs.Container) -> int:
+    ...
+    """,
+)
+
+
 class TestTakesContainer:
     @pytest.mark.parametrize(
         "factory",
@@ -347,16 +411,18 @@ def factory(foo: svcs.Container):
 
         assert svcs._core._takes_container(factory)
 
-    def test_annotation_str(self):
+    @pytest.mark.parametrize(
+        "module_source", takes_containers_annotation_string_modules
+    )
+    def test_annotation_str(self, module_source, create_module):
         """
-        Return true if the first argument is annotated as `svcs.Container`
+        Return `True` if the first argument is annotated as `svcs.Container`
         using a string.
         """
 
-        def factory(bar: "svcs.Container"):
-            ...
+        module = create_module(module_source)
 
-        assert svcs._core._takes_container(factory)
+        assert svcs._core._takes_container(module.factory)
 
     def test_catches_invalid_sigs(self):
         """