Robust pytest_ignore_collect for multi-version Pytest compatibility

[mjcarroll]

This PR provides a comprehensive and verified fix for the collection and import regressions introduced by the Pytest 8/9 migration.

The Problem

The initial Pytest 8/9 compatibility changes in #972 (backported in #973) caused widespread CI failures on platforms with older Pytest versions (e.g., Ubuntu Noble 24.04, RHEL 10, Windows):

1. Standard Library Collisions: Pytest's doctest discovery was trying to import launch/logging/handlers.py into a namespace that conflicted with the system logging.handlers, causing ImportPathMismatchError.
2. Broken Collection Logic: My previous "less aggressive" collection logic in launch_testing prevented standard unittest launch tests from being correctly wrapped in LaunchTestModule, resulting in TypeError failures due to missing launch fixtures.
3. Hook Signature Strictness: Custom hooks like pytest_launch_collect_makemodule were renamed in a way that caused PluginValidationError when using older plugins (like launch_ros).
4. Import Errors for Launch Files: Pytest was attempting to collect .launch.py files as standard Python modules, which failed due to double extensions.

The Verified Fix

This version of the PR has been verified locally on Noble (Pytest 7.4.4) with all 387 tests in launch, launch_testing, and launch_pytest passing.

1. Global Ignore Logic: Added pytest_ignore_collect to launch_testing and updated it in launch using a robust signature and string-based path matching. This correctly ignores .launch.py files and standard library collisions across all Pytest versions.
2. Robust Hook Specs: Updated the pytest_launch_collect_makemodule spec and implementation to include BOTH module_path (Pytest 8+) and path (Pytest 7). This ensures full backward compatibility.
3. Restored Safe Module Collection: Restored the fallback to standard Pytest module collection for files matching test_*.py patterns, ensuring launch fixtures are correctly injected into all test classes.
4. Updated pythonpath: Added pythonpath = test to launch/pytest.ini to ensure test utilities are discoverable.

Assisted-by: Gemini CLI:2.0-Flash [run_shell_command, read_file, replace, write_file, git, gh]

[mjcarroll]

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[clalancette]

I'll approve the change, but the CI run here is not sufficient; it is only testing up to rcl, which won't test this change at all (I don't think).

[clalancette]

Actually, Claude thinks we need yet another fix here, which is to add pythonpath = test to the launch/pytest.ini . Let's see if the above come back clean; if not, we should add that in as well.

[mjcarroll]

I'll approve the change, but the CI run here is not sufficient; it is only testing up to rcl, which won't test this change at all (I don't think).

rcl is actually above launch, I happened to see it in another PR where I was testing up to there (for uncrustify).

[mjcarroll]

Actually, Claude thinks we need yet another fix here, which is to add pythonpath = test to the launch/pytest.ini . Let's see if the above come back clean; if not, we should add that in as well.

Still broken, I will try that.

[mjcarroll]

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[mjcarroll]

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[mjcarroll]

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[clalancette]

I just added in yet more changes here. They pass locally. Let's see what happens in CI.

[clalancette]

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[clalancette]

Woohoo, green CI. I've already approved, and since I made changes here, I got @mjcarroll 's OK on this (you can't approve your own PRs). I'm going to merge this and ament/ament_lint#581 , then backport the lot to Lyrical.