Isolate Test Database per Worker with Transactions
Wrap each test in a transaction that rolls back so parallel workers never see each other's data and tests are order-independent.
Task
Add BEGIN; -- run test; ROLLBACK; to the test suite so regressions are caught automatically on every pull request.
When to use this
A refactor passes existing tests but breaks BEGIN; -- run test; ROLLBACK;, shipping a silent regression to users.
Prerequisites
- A test runner configured (Vitest or Jest)
- Source code with testable units
Steps
1. Configure BEGIN; -- run test; ROLLBACK; in the project configuration file with the recommended defaults.
BEGIN; -- run test; ROLLBACK;
Expected output: The configuration is accepted and BEGIN; -- run test; ROLLBACK; runs without errors on the first invocation.
2. Run the check locally to verify BEGIN; -- run test; ROLLBACK; produces the expected result before pushing.
pnpm test
Expected output: Local run matches CI behavior; no surprises after push.
3. Add the gate to the CI pipeline so BEGIN; -- run test; ROLLBACK; blocks merge on failure.
- name: Run add test database isolation
run: pnpm test
Expected output: Pull requests with failing BEGIN; -- run test; ROLLBACK; are blocked from merging.
Troubleshooting
Problem
The check passes locally but fails in CI
Solution
Pin dependency versions and the runtime to match CI exactly; reproduce with the same Docker image or act.
Problem
Configuration is rejected with a schema error
Solution
Check the tool version matches the config schema; older versions may not support newer fields.
Limitations
- The gate only runs on events that trigger the workflow; locally pushed commits bypass it.
- Configuration drift is possible if someone edits settings outside version control.
Cover the regression path
Start by measuring the problem. Wrap each test in a transaction that rolls back so parallel workers never see each other’s data and tests are order-independent. The most common mistake is adding the gate without first confirming it catches the issue you care about. Run BEGIN; – run test; ROLLBACK; against the current codebase and inspect the output before wiring it into CI.
BEGIN; -- run test; ROLLBACK;Keep tests maintainable
Once the gate is in place, make failures actionable. A failing BEGIN; – run test; ROLLBACK; should point to the exact file and line, not a generic error. Pin the tool version in the lockfile so a upstream release does not silently change behavior. Review the gate output in every pull request just like a test result.