Make the import side-effect tests pass on Windows and under mypy tests/

The first cut failed CI in two places, neither in the fix itself:

- mypy tests/ (which CI runs, alongside mypy vgi/) flagged four
  `type: ignore[type-var]` comments as unused.
- On Windows, test_storage_is_still_created_on_first_use looked for the
  database under the temporary HOME, but platformdirs asks Windows for its
  folders directly and ignores HOME and XDG there, so the store landed in
  the real LOCAL_APPDATA. The isolated environment now also sets
  platformdirs' WIN_PD_OVERRIDE_LOCAL_APPDATA and WIN_PD_OVERRIDE_APPDATA.

The import test also now asserts, inside the subprocess, that the storage
descriptor was never resolved, reading it through Function.__dict__ so the
read cannot resolve it either. That check does not depend on where any
platform keeps its state directory. The import tests still fail on the
pre-fix code.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: rustyconover

tests/test_import_side_effects.py

@@ -45,6 +45,13 @@ def on_bind(cls, params):
     @classmethod
     def process(cls, params, state, out):
         out.finish()
+
+
+# The direct check, independent of where a platform keeps its state directory:
+# reading through __dict__ does not invoke the descriptor.
+from vgi.function import Function
+
+assert Function.__dict__["storage"]._resolved is None, "storage was resolved during import"
 """
 
 
@@ -59,6 +66,10 @@ def _isolated_env(home: Path) -> dict[str, str]:
     env["HOME"] = str(home)
     for name in ("XDG_STATE_HOME", "XDG_DATA_HOME", "XDG_CACHE_HOME", "XDG_CONFIG_HOME"):
         env[name] = str(home / name.lower())
+    # platformdirs asks Windows for its folders directly and ignores HOME and
+    # XDG there, but honors these overrides.
+    for name in ("LOCAL_APPDATA", "APPDATA"):
+        env[f"WIN_PD_OVERRIDE_{name}"] = str(home / name.lower())
     return env
 
 
@@ -127,7 +138,7 @@ def test_a_concrete_class_is_validated(self) -> None:
         """Control: without an abstract member, the invalid argument type is rejected."""
         with pytest.raises(TypeError, match="must be a dataclass"):
 
-            class Concrete(TableFunctionGenerator[_NotADataclass, None]):  # type: ignore[type-var]
+            class Concrete(TableFunctionGenerator[_NotADataclass, None]):
                 @classmethod
                 def on_bind(cls, params):  # type: ignore[no-untyped-def]
                     raise NotImplementedError
@@ -139,7 +150,7 @@ def process(cls, params, state, out):  # type: ignore[no-untyped-def]
     def test_an_abstract_classmethod_marks_the_class_abstract(self) -> None:
         """An inherited-concrete class that adds an abstract classmethod skips validation."""
 
-        class WithAbstractClassmethod(TableFunctionGenerator[_NotADataclass, None]):  # type: ignore[type-var]
+        class WithAbstractClassmethod(TableFunctionGenerator[_NotADataclass, None]):
             @classmethod
             def on_bind(cls, params):  # type: ignore[no-untyped-def]
                 raise NotImplementedError
@@ -158,7 +169,7 @@ def extra(cls) -> None:
     def test_an_abstract_staticmethod_marks_the_class_abstract(self) -> None:
         """An abstract staticmethod is recognized through its raw attribute too."""
 
-        class WithAbstractStaticmethod(TableFunctionGenerator[_NotADataclass, None]):  # type: ignore[type-var]
+        class WithAbstractStaticmethod(TableFunctionGenerator[_NotADataclass, None]):
             @classmethod
             def on_bind(cls, params):  # type: ignore[no-untyped-def]
                 raise NotImplementedError
@@ -177,7 +188,7 @@ def extra() -> None:
     def test_an_abstract_property_marks_the_class_abstract(self) -> None:
         """An abstract property is recognized through its raw attribute too."""
 
-        class WithAbstractProperty(TableFunctionGenerator[_NotADataclass, None]):  # type: ignore[type-var]
+        class WithAbstractProperty(TableFunctionGenerator[_NotADataclass, None]):
             @classmethod
             def on_bind(cls, params):  # type: ignore[no-untyped-def]
                 raise NotImplementedError