Enable parallel pytest execution by default via pytest-xdist

[Copilot]

Tests ran sequentially despite pytest-xdist already being a dev dependency. This adds -n auto as the default addopts and wires up a proper CI test workflow.

Changes

• pyproject.toml — Adds [tool.pytest.ini_options] with addopts = "-n auto", making parallel execution the default for all pytest invocations without requiring any flag
• README.md — Updates testing section to use uv run pytest consistently and reflects that parallel execution is now the default (removes the stale note suggesting it might be slower)
• .github/workflows/test.yml (new) — CI workflow on push/PR to main using uv sync --all-extras + uv run pytest tests/ -n auto -v; scoped to contents: read

[tool.pytest.ini_options]
addopts = "-n auto"

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Code Quality] Enable parallel pytest execution to speed up test suite</issue_title>
<issue_description>### Description

The test suite (18 files, 5,358 lines) runs sequentially, taking longer than necessary. Enabling parallel execution with pytest-xdist can significantly reduce test execution time.

Problem

From the Performance Research discussion (#219):

• Tests run sequentially without parallelization
• Identified as high-priority optimization (Week 1-2)
• Target: Speed up test execution by 40%
• pytest-xdist not currently used despite being in dev dependencies

Current State

Tests run with: uv run pytest tests/

No parallel execution configured.

Suggested Changes

1. Update test execution command to use parallel workers:

   uv run pytest tests/ -n auto

   The -n auto flag automatically uses CPU count for optimal parallelization

2. Add pytest-xdist to dev dependencies (if not already present):

   [project.optional-dependencies]
   dev = [
       "pytest>=8.3.4",
       "pytest-xdist>=3.6.1",  # Add this
       "pytest-mock>=3.14.0"
   ]

3. Update documentation:

   • README.md test execution examples: uv run pytest tests/ -n auto
   • CI workflow test commands: uv run pytest tests/ -n auto -v

4. Configure pytest.ini for parallel-safe settings:

   [tool.pytest.ini_options]
   addopts = "-n auto"

Files Affected

• pyproject.toml (add pytest-xdist dependency if missing)
• README.md (update test execution examples)
• Future test.yml workflow (use -n auto flag)
• .github/actions/*/build-steps/action.yml (update test commands)

Success Criteria

• ✅ Test suite completes 30-40% faster with parallel execution
• ✅ All tests remain stable and pass with parallelization
• ✅ No race conditions or test isolation issues
• ✅ CI workflows use parallel execution
• ✅ Local development workflow benefits from faster tests

Priority

High - High-priority Week 1-2 optimization with significant time savings

Effort Estimate

20 minutes (add dependency, update commands, verify no race conditions)

Implementation Notes

Test isolation checks:

• Ensure tests don't share global state
• Verify mock isolation between parallel tests
• Check that file I/O tests use unique temp paths
• Validate thread-safe operations in tests

Performance measurement:

• Measure baseline: time uv run pytest tests/
• Measure parallel: time uv run pytest tests/ -n auto
• Document speedup in PR description

Source

Extracted from Daily Perf Improver discussion abhimehro/ctrld-sync#219 - High Priority Week 1-2 optimization

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Comments on the Issue (you are @copilot in this section)

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• Fixes [Code Quality] Enable parallel pytest execution to speed up test suite #367

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[Copilot]

Pull request overview

This PR enables parallel test execution by default using pytest-xdist, addressing a high-priority performance optimization. The changes configure pytest to automatically use all available CPU cores via the -n auto flag, eliminating the need to pass this flag manually. A new CI workflow is introduced to ensure tests run in parallel in GitHub Actions.

Changes:

• Adds [tool.pytest.ini_options] with addopts = "-n auto" to enable parallel test execution by default
• Updates README.md documentation to reflect parallel execution as the default and migrate all examples to use uv run pytest
• Introduces .github/workflows/test.yml CI workflow for automated testing on push/PR to main

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
pyproject.toml	Adds pytest configuration to enable parallel execution by default via -n auto in addopts
README.md	Updates testing documentation to show parallel execution is default, standardizes on uv run pytest commands
.github/workflows/test.yml	New CI workflow using uv for dependency management and running parallel tests on push/PR

[Copilot]

The -n auto flag is redundant here since it's already configured as the default in pyproject.toml via addopts = "-n auto". Consider removing -n auto from this command to avoid duplication and rely on the centralized configuration. This makes the pytest configuration easier to maintain in one place.

Suggested change

	run: uv run pytest tests/ -n auto -v
	run: uv run pytest tests/ -v

[Copilot]

The comment states "uses -n auto by default via pyproject.toml" which is accurate, but then the example command explicitly includes -n auto again. This is redundant since running uv run pytest tests/ (without -n auto) will already use parallel execution due to the addopts configuration. Consider updating the comment to clarify that the flag is optional/redundant here, or remove the -n auto from the example to demonstrate relying on the default configuration.

[abhimehro]

Closing: duplicate of #406, both fail CI. Consolidate if feature desired.