Run the unit test suite in GitHub Actions

[dmccoystephenson]

Summary

• A Tests GitHub Actions workflow is added at .github/workflows/tests.yml. It runs on pull requests targeting main and on pushes to main, installs pygame on Python 3.12, syntax-checks the top-level modules with py_compile, and runs python -m unittest discover -s tests.
• The repository is checked out without the Viron submodule, as proposed in Add CI to run the unit test suite on pull requests #17: the suite stubs Viron in sys.modules, so the submodule is not needed.
• The push trigger on main goes beyond the issue's pull-request-only proposal. It is included so that main accumulates a run history against which PR results can be compared. It can be dropped if unwanted.
• The py_compile list differs from the one in Add CI to run the unit test suite on pull requests #17: render_window_example.py no longer exists in the tree, and headless_run.py, usage_reporting.py and trace_client.py, which have been added since, are included.
• README.md ("Running the tests") now mentions the workflow.

Closes #17

Test plan

• python3 -m unittest discover -s tests run locally (Python 3.8.10): Ran 106 tests, OK
• python3 -m py_compile main.py graphik.py __init__.py render_window.py headless_run.py usage_reporting.py trace_client.py passes locally
• The workflow file parses as YAML
• The workflow's first run on this PR is green (the workflow has never run before, so this run is its first real validation)

Merge note

.github/workflows/* is on this loop's do-not-auto-merge list, and #17 itself anticipates human review. This PR is therefore left open for the owner to merge; it is not auto-merged.

Deferred issues

• Decide whether per-location colours should be stable across frames #24: blocked on an owner decision about whether colours should be stable across frames.
• Add text-based UI support to library for users #11, Support drawing environments with multiple grids #2: feature work that is too large for this cycle's scope.

This PR description was drafted during a Gardener session (https://github.com/Stephenson-Software/gardener).

🤖 Generated with Claude Code

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drafted by Claude on behalf of Daniel Stephenson

[dmccoystephenson]

Self-review rubric (the anchor is the workflow's own first run: https://github.com/Preponderous-Software/patchwork/actions/runs/36685845233 — pygame-2.6.1 installed, Ran 106 tests in 21.619s, OK on Python 3.12; the same 106 were also run locally on Python 3.8.10, OK):

• Scope: PASS, with one judgment call. Only .github/workflows/tests.yml (new) and one README paragraph are changed. The push: branches: [main] trigger goes beyond Add CI to run the unit test suite on pull requests #17's pull-request-only proposal. It is kept so that main builds a run history, and it can be removed on request.
• Tests-new: PASS (not applicable). No new functions were added; the change is CI configuration only.
• Tests-fix: not applicable. Not a bug fix.
• Sibling structure: PASS (not applicable). No .github/workflows/ directory existed, so there were no siblings to follow.
• Sibling renames: not applicable. Nothing was renamed.
• Docs: PASS. README "Running the tests" now describes the workflow, including its triggers and the submodule-less checkout. create_environments.bat, up.bat and down.bat are unaffected.
• Issue resolution: PASS. Add CI to run the unit test suite on pull requests #17 asked for a workflow on PRs to main running python -m unittest discover -s tests, without submodules, on Python >= 3.10, with pip install pygame and a py_compile step. Each of these is present. The compile list was updated for the current tree: render_window_example.py no longer exists, and headless_run.py, usage_reporting.py and trace_client.py were added.
• Manual validation: PASS. The run linked above ran against the PR head.

Findings:

• .github/workflows/tests.yml:18 — actions/checkout@v4 and actions/setup-python@v5 are pinned by major-version tag, not by commit SHA. This is the common convention and is acceptable for a read-only (contents: read) test job, but SHA pinning may be preferred.
• .github/workflows/tests.yml:23 — pygame is installed unpinned. A future pygame release could turn CI red without any change in this repository. No other dependency manifest exists in the repo to pin it against.

Merge hold: .github/workflows/* is on the do-not-auto-merge list, so this PR is left open for owner review and merge.

This review comment was drafted during a Gardener session (https://github.com/Stephenson-Software/gardener).

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drafted by Claude on behalf of Daniel Stephenson