Skip test that cannot be ran in parallel

[kingbuzzman]

There are weird tests in TestLiveServer.test_settings_before/test_settings_restored that requires xdist to not be used. Since they set a global variable, and due to how xdist works, you cannot guarantee the order or the same worker.

I'm in two minds about this... My gut tells me to remove this test.. but I want to first get your opinion.

[Copilot]

Pull Request Overview

This PR addresses test reliability issues by conditionally skipping tests that cannot run properly in parallel test environments. The tests in question modify global Django settings and require specific execution order, which is incompatible with pytest-xdist's parallel execution model.

Key changes:

• Skip problematic tests when pytest-xdist is detected via environment variable
• Add os import to support the skipif condition

Comments suppressed due to low confidence (2)

tests/test_fixtures.py:447

• The skip reason message is too brief and doesn't explain why xdist usage is problematic. Consider a more descriptive message like 'Cannot run in parallel - modifies global settings' to help developers understand the constraint.

    @pytest.mark.skipif("PYTEST_XDIST_WORKER" in os.environ, reason="xdist in use")

tests/test_fixtures.py:463

• The skip reason message is too brief and doesn't explain why xdist usage is problematic. Consider a more descriptive message like 'Cannot run in parallel - depends on global state from previous test' to help developers understand the constraint.

    @pytest.mark.skipif("PYTEST_XDIST_WORKER" in os.environ, reason="xdist in use")