fix(warnings): avoid MissingSpecAttributeWarning if property type is missing or optional (#258)

Fixes #257

Author: mcous

.github/actions/setup/action.yml

@@ -7,7 +7,7 @@ inputs:
         default: "3.12"
     poetry-version:
         description: "Poetry version to install"
-        default: "1.7.0"
+        default: "2.1.1"
     cache:
         description: "Cache directory"
         default: "${{ runner.temp }}/cache"
@@ -17,19 +17,19 @@ runs:
     steps:
         - name: "Set up Python"
           id: setup-python
-          uses: actions/setup-python@v4
+          uses: actions/setup-python@v5
           with:
               python-version: ${{ inputs.python-version }}
               update-environment: false
 
         - name: "Set up Python 3.12 for Poetry"
           id: setup-poetry-python
-          uses: actions/setup-python@v4
+          uses: actions/setup-python@v5
           with:
               python-version: 3.12
 
         - name: "Set up dependency cache"
-          uses: actions/cache@v3
+          uses: actions/cache@v4
           with:
               key: ${{ runner.os }}-${{ steps.setup-poetry-python.outputs.python-version }}-${{ steps.setup-python.outputs.python-version }}-${{ inputs.poetry-version }}-${{ hashFiles('poetry.lock') }}
               path: ${{ inputs.cache }}

.github/workflows/ci.yml

@@ -10,11 +10,22 @@ on:
 jobs:
     test:
         name: "Test Python ${{ matrix.python-version }} on ${{ matrix.os }}"
-        runs-on: ${{ matrix.os }}-latest
+        runs-on: ${{ matrix.os }}
         strategy:
+            fail-fast: false
             matrix:
-                os: [Ubuntu, Windows, macOS]
-                python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
+                os: [ubuntu-latest, windows-latest, macos-latest]
+                python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+                include:
+                    - os: ubuntu-22.04
+                      python-version: "3.7"
+                    - os: windows-latest
+                      python-version: "3.7"
+                    - os: macos-13
+                      python-version: "3.7"
+        permissions:
+            id-token: write
+
         steps:
             - name: "Check out repository"
               uses: actions/checkout@v4
@@ -28,7 +39,9 @@ jobs:
               run: poetry run poe test-ci
 
             - name: "Upload coverage report"
-              uses: codecov/codecov-action@v3
+              uses: codecov/codecov-action@v5
+              with:
+                  use_oidc: true
 
     check:
         name: "Lint and type checks"

decoy/spy_core.py

@@ -2,7 +2,17 @@
 import inspect
 import functools
 import warnings
-from typing import Any, Dict, NamedTuple, Optional, Tuple, Type, Union, get_type_hints
+from typing import (
+    Any,
+    Dict,
+    NamedTuple,
+    Optional,
+    Tuple,
+    Type,
+    Union,
+    Sequence,
+    get_type_hints,
+)
 
 from .spy_events import SpyInfo
 from .warnings import IncorrectCallWarning, MissingSpecAttributeWarning
@@ -112,12 +122,15 @@ def create_child_core(self, name: str, is_async: bool) -> "SpyCore":
         source = self._source
         child_name = f"{self._name}.{name}"
         child_source = None
+        child_found = False
 
         if inspect.isclass(source):
             # use type hints to get child spec for class attributes
             child_hint = _get_type_hints(source).get(name)
             # use inspect to get child spec for methods and properties
             child_source = inspect.getattr_static(source, name, child_hint)
+            # record whether a child was found before we make modifications
+            child_found = child_source is not None
 
             if isinstance(child_source, property):
                 child_source = _get_type_hints(child_source.fget).get("return")
@@ -136,7 +149,9 @@ def create_child_core(self, name: str, is_async: bool) -> "SpyCore":
                     # signature reporting by wrapping it in a partial
                     child_source = functools.partial(child_source, None)
 
-        if child_source is None and source is not None:
+        child_source = _unwrap_optional(child_source)
+
+        if source is not None and child_found is False:
             # stacklevel: 4 ensures warning is linked to call location
             warnings.warn(
                 MissingSpecAttributeWarning(f"{self._name} has no attribute '{name}'"),
@@ -215,3 +230,24 @@ def _get_type_hints(obj: Any) -> Dict[str, Any]:
         return get_type_hints(obj)
     except Exception:
         return {}
+
+
+def _unwrap_optional(source: Any) -> Any:
+    """Return the source's base type if it's a optional.
+
+    If the type is a union of more than just T | None,
+    bail out and return None to avoid potentially false warnings.
+    """
+    origin = getattr(source, "__origin__", None)
+    args: Sequence[Any] = getattr(source, "__args__", ())
+
+    # TODO(mc, 2025-03-19): support larger unions? might be a lot of work for little payoff
+    if origin is Union:
+        if len(args) == 2 and args[0] is type(None):
+            return args[1]
+        if len(args) == 2 and args[1] is type(None):
+            return args[0]
+
+        return None
+
+    return source

tests/fixtures.py

@@ -1,6 +1,6 @@
 """Common test fixtures."""
 from functools import lru_cache
-from typing import Any, Generic, TypeVar
+from typing import Any, Generic, TypeVar, Optional, Union
 
 
 class SomeClass:
@@ -28,6 +28,11 @@ def primitive_property(self) -> str:
         """Get a primitive computed property."""
         raise NotImplementedError()
 
+    @property
+    def mystery_property(self):  # type: ignore[no-untyped-def] # noqa: ANN201
+        """Get a property without type annotations."""
+        raise NotImplementedError()
+
     @lru_cache(maxsize=None)  # noqa: B019
     def some_wrapped_method(self, val: str) -> str:
         """Get a thing through a wrapped method."""
@@ -48,6 +53,21 @@ def child(self) -> SomeClass:
         """Get the child instance."""
         raise NotImplementedError()
 
+    @property
+    def optional_child(self) -> Optional[SomeClass]:
+        """Get the child instance."""
+        raise NotImplementedError()
+
+    @property
+    def union_none_child(self) -> Union[None, SomeClass]:
+        """Get the child instance."""
+        raise NotImplementedError()
+
+    @property
+    def union_child(self) -> Union[SomeClass, "SomeAsyncClass"]:
+        """Get the child instance."""
+        raise NotImplementedError()
+
 
 class SomeAsyncClass:
     """Async testing class."""

tests/test_spy_core.py

@@ -445,6 +445,7 @@ def test_warn_if_called_incorrectly() -> None:
 def test_warn_if_spec_does_not_have_method() -> None:
     """It should trigger a warning if bound_args is called incorrectly."""
     class_subject = SpyCore(source=SomeClass, name=None)
+    nested_class_subject = SpyCore(source=SomeNestedClass, name=None)
     func_subject = SpyCore(source=some_func, name=None)
     specless_subject = SpyCore(source=None, name="anonymous")
 
@@ -458,6 +459,29 @@ def test_warn_if_spec_does_not_have_method() -> None:
         warnings.simplefilter("error")
         class_subject.create_child_core("foo", False)
 
+    # property access without types should not warn
+    with warnings.catch_warnings():
+        warnings.simplefilter("error")
+        class_subject.create_child_core("mystery_property", False)
+
+    # property access should be allowed through optionals
+    with warnings.catch_warnings():
+        warnings.simplefilter("error")
+        parent = nested_class_subject.create_child_core("optional_child", False)
+        parent.create_child_core("primitive_property", False)
+
+    # property access should be allowed through None unions
+    with warnings.catch_warnings():
+        warnings.simplefilter("error")
+        parent = nested_class_subject.create_child_core("union_none_child", False)
+        parent.create_child_core("primitive_property", False)
+
+    # property access should not be checked through unions
+    with warnings.catch_warnings():
+        warnings.simplefilter("error")
+        parent = nested_class_subject.create_child_core("union_child", False)
+        parent.create_child_core("who_knows", False)
+
     # incorrect class usage should warn
     with pytest.warns(
         MissingSpecAttributeWarning, match="has no attribute 'this_is_wrong'"
@@ -469,3 +493,17 @@ def test_warn_if_spec_does_not_have_method() -> None:
         MissingSpecAttributeWarning, match="has no attribute 'this_is_wrong'"
     ):
         func_subject.create_child_core("this_is_wrong", False)
+
+    # incorrect nested property usage should warn
+    with pytest.warns(
+        MissingSpecAttributeWarning, match="has no attribute 'this_is_wrong'"
+    ):
+        parent = nested_class_subject.create_child_core("optional_child", False)
+        parent.create_child_core("this_is_wrong", False)
+
+    # incorrect nested property usage should warn
+    with pytest.warns(
+        MissingSpecAttributeWarning, match="has no attribute 'this_is_wrong'"
+    ):
+        parent = nested_class_subject.create_child_core("union_none_child", False)
+        parent.create_child_core("this_is_wrong", False)