fix(zarr-indexing): satisfy lint rules CI enables and the pinned ruff does not

CI's ruff runs a broader rule set than the version pinned in
.pre-commit-config.yaml, so three violations passed locally and failed
there. All three are worth fixing on their own terms rather than
suppressing.

The BadIndex fixtures return 2.5 from __index__ deliberately — the point is
an object that violates the protocol, so the package can be shown rejecting
it. PLE0305 reads that as a mistake.  keeps the runtime
lie the test needs while saying the lie is intentional, and drops the
type: ignore it needed for mypy.

The stateful test imported ;
 is the form the rest of the
suite uses, and the import block re-sorts around it.

Assisted-by: ClaudeCode:claude-fable-5

Author: d-v-b

packages/zarr-indexing/tests/test_lazy_array.py

@@ -14,7 +14,7 @@
 import pickle
 from concurrent.futures import ThreadPoolExecutor
 from dataclasses import replace
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Any, cast
 
 import numpy as np
 import pytest
@@ -62,8 +62,10 @@ def __int__(self) -> int:
 
 
 class BadIndex:
+    """An `__index__` that lies: the protocol requires an integer."""
+
     def __index__(self) -> int:
-        return 2.5  # type: ignore[return-value]
+        return cast("int", 2.5)
 
 
 def reference() -> np.ndarray[Any, np.dtype[np.int64]]:

packages/zarr-indexing/tests/test_lazy_array_stateful.py

@@ -26,13 +26,13 @@
 import pytest
 from hypothesis import settings
 
-import zarr_indexing.testing.stateful as stateful
 from zarr_indexing import LazyArray, ReadContext
 from zarr_indexing.reader import basic_reader, numpy_reader
 from zarr_indexing.testing import (
     DEFAULT_SETTINGS,
     ChainedIndexingStateMachine,
     state_machine_test,
+    stateful,
 )
 
 

packages/zarr-indexing/tests/test_transform.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from typing import cast
+
 import numpy as np
 import pytest
 
@@ -28,8 +30,10 @@ def __int__(self) -> int:
 
 
 class BadIndex:
+    """An `__index__` that lies: the protocol requires an integer."""
+
     def __index__(self) -> int:
-        return 2.5  # type: ignore[return-value]
+        return cast("int", 2.5)
 
 
 class TestIndexTransformConstruction: