Testing/CI/tooling consistency (#9,#20,#21,#22,#23,#28) (#59)

Co-authored-by: claude <claude@jpaul.io>
Co-committed-by: claude <claude@jpaul.io>

modules/14-continuous-integration/lab/ci-starter.yml

@@ -33,14 +33,16 @@ jobs:
         with:
           python-version: "3.12"
 
-      # Step 3: install the tools the checks need — the test runner and the linter from Module 13.
+      # Step 3: install the linter (ruff), the new tool this module adds. The test runner is
+      # Python's standard-library unittest from Module 13 — nothing to install for it.
       - name: Install tools
-        run: pip install pytest ruff
+        run: pip install ruff
 
       # Step 4: lint. Style and obvious-mistake check. Fails the job on any finding (non-zero exit).
       - name: Lint
         run: ruff check .
 
-      # Step 5: test. The Module 13 tests. A single failing assertion fails the whole job.
+      # Step 5: test. The Module 13 tests, run with the stdlib unittest runner. A single failing
+      # assertion fails the whole job.
       - name: Test
-        run: pytest -q
+        run: python -m unittest