SG-42073 Fixes segmentation faults on Python 3.13 with PySide6 6.8.3+ on macOS

[julien-lang]

Fixes segmentation faults on Python 3.13 with PySide6 6.8.3+ on macOS.

Root Cause:
Python 3.13 with PySide6 6.8.3+ has stricter Qt object lifecycle management. Test-created FileModel objects hold references to engine/app, and pytest'"'"'s addCleanup() destroys them AFTER tearDown() completes. When _model.destroy() tries to access the already-freed engine memory → segfault.

Solution:

• Remove addCleanup() for engine and bg_task_manager
• Implement explicit tearDown() with proper cleanup order:
  1. Shut down background task manager + wait for threads
  2. CRITICAL FIX: Destroy _model BEFORE engine.destroy()
  3. Wait for metrics dispatcher threads to complete
  4. Destroy engine
  5. Final Qt event processing

Testing:

• Python 3.13.10 + PySide6 6.8.3: ✅ 14/15 runs successful (was ~40%)
• Python 3.11 + PySide6 6.6.3: ✅ 100% success
• All CI platforms passing

Key Fix:
6 lines (117-122) that explicitly destroy test-created Qt objects before engine destruction, preventing access to freed memory. Follows tk-framework-shotgunutils cleanup pattern.

Related: #171

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 31.87%. Comparing base (c93ee8a) to head (72adffe).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #172      +/-   ##
==========================================
+ Coverage   31.86%   31.87%   +0.01%     
==========================================
  Files          68       68              
  Lines        7658     7658              
==========================================
+ Hits         2440     2441       +1     
+ Misses       5218     5217       -1     

Flag	Coverage Δ
Linux	31.87% <ø> (+0.01%)	⬆️
Python-3.10	31.86% <ø> (ø)
Python-3.11	31.86% <ø> (ø)
Python-3.13	31.86% <ø> (+0.01%)	⬆️
Python-3.9	31.88% <ø> (+0.01%)	⬆️
Windows	18.69% <ø> (ø)
macOS	31.86% <ø> (ø)

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[Copilot]

Pull request overview

Fixes intermittent segmentation faults in macOS test runs on Python 3.13 + PySide6 6.8.3+ by enforcing a deterministic Qt/engine teardown order (destroying test-created Qt objects before destroying the engine) and expanding async teardown waits.

Changes:

• Removed addCleanup() for engine and background task manager in favor of an explicit tearDown() with ordered cleanup.
• Added explicit shutdown/waits for background/metrics dispatcher threads and aggressive Qt event processing during teardown.
• Increased default wait_for() timeout from 2000ms to 5000ms.

Comments suppressed due to low confidence (1)

tests/python/workfiles2_test_base.py:1

• The timeout docstring text is duplicated (“in milliseconds (default 5000ms) … in milliseconds (default 5000ms)”). Please fix to a single, clear description (e.g., “Timeout in milliseconds (default 5000ms).”).

# Copyright (c) 2020 Shotgun Software Inc.

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[carlos-villavicencio-adsk]

Great job 🚀