Restore numpy in sys.modules after test_no_numpy_int_type

[zhaoruizhe81]

Link to issue

Fixes #4852

Description of change

TestNoNumpyIntegerBaseType.test_no_numpy_int_type pops numpy from sys.modules to simulate a no-numpy environment, but never restores it. This PR saves the module entry before popping and restores it in a finally block, so the test no longer leaks global state into the rest of the pytest process.

The test's intent is fully preserved: inside the popped window get_module("numpy", should_load=False) still returns None (it reads sys.modules.get(name, None) in _plotly_utils/optional_imports.py), so _get_int_type() still returns (int,) and the assertion still exercises the no-numpy path. In a true no-numpy environment get_module returns None, the restore branch is skipped, and behavior is unchanged.

Demo

N/A - this is a test-infrastructure change with no user-facing behavior.

Testing strategy

Verified in an isolated venv (CPython 3.13.12, numpy 2.5.3, pandas 3.0.6, pytest 9.1.1, editable install of this repo) on main@3f8a650:

• Reproduced the bug on the unmodified tree: running the test file in-process via pytest.main(["-q", "tests/test_optional/test_utils/test_utils.py"]) (all tests pass, exit code 0) and then executing import numpy in that same process raises RecursionError: maximum recursion depth exceeded, because the re-import re-executes numpy/__init__.py. A minimal import numpy; sys.modules.pop("numpy"); import numpy reproduces the same error.
• With the fix:
  • python -m pytest tests/test_optional/test_utils/test_utils.py -q -> 26 passed.
  • Same in-process driver as above: pytest exits 0, import numpy afterwards succeeds, and sys.modules["numpy"] is the very same module object as before the test flow (is check is True), with np.integer intact.
  • python -m pytest tests/test_optional/ -q --ignore=tests/test_optional/test_kaleido/test_kaleido.py --ignore=tests/test_optional/test_px/test_imshow.py -> 3 failed, 1241 passed, 26 skipped, 4 xfailed, identical before and after the change. The two ignored modules require optional deps not installed locally (pdfrw, xarray); the 3 failures are pre-existing environment-related failures in tests/test_optional/test_offline/test_offline.py, present in the unmodified baseline as well, so there is no regression from this change.

Additional information (optional)

This is the root cause of the "odd recursion error" in #4622, where the workaround was to move the affected test above this one. Popping numpy from sys.modules without restoring it makes the file order-fragile: any test added after test_no_numpy_int_type that imports numpy will break.

If maintainers prefer, an equivalent fix is mock.patch.dict(sys.modules, {"numpy": None}), the pattern already used in tests/test_io/test_renderers.py - happy to switch.

Guidelines

• I have reviewed the pull request guidelines and the Code of Conduct and confirm that this PR follows them.
• I have added an entry to the changelog if needed (not required for documentation PRs).