| name | bug-repro-test-first |
| description | Start bug work by proving the reported bug with a failing regression test before attempting a fix. Use when the user reports a bug, asks to fix a bug, or describes a regression, failing behavior, or reproduction case with a plausible test surface. |
Bug Repro Test First
Use this when the user reports a bug or asks for a bug fix.
Source
Read references/tangming2005-test-first-bug-report.md if you need the source note behind this workflow.
Rule
Do not start by fixing the code.
First write or adapt a test that fails for the reported bug. The test is the definition of the bug.
If there is no useful test surface, create the narrowest reproducible check available instead (a script under scripts/, a curl against a local server, an e2e case), then state why a regression test was not practical before fixing production code.
Workflow
-
Reproduce or inspect the failure enough to choose the narrowest useful test. Tests are co-located *.test.ts in packages/vana-sdk/src and use Vitest with mocked viem clients and fetch.
-
Add a failing test that captures the bug, preferably near existing coverage for the same behavior. Assert on the public contract (route status and body shape, exported function result, error code or class), not on log text or private helpers.
-
Run that test and confirm it fails for the expected reason:
cd packages/vana-sdk && npx vitest run src/<file>.test.ts
No build is needed for unit tests; turbo builds workspace dependencies first when you go through the root npm test.
-
Only then change production code.
-
Run the same test and confirm it passes.
-
Run the smallest relevant surrounding test/check slice, then the repo proof before handoff:
npm run typecheck && npm run lint && npm test
Parallel Fixes
If the user explicitly asks for subagents or the active tool policy permits delegation for this task, spawn fix workers only after the failing test exists. Give each worker the failing test command and a disjoint write scope.
If delegation is not available or not appropriate, fix locally after proving the failing test.
Done
- The bug has a regression test.
- The regression test, or documented fallback check, failed before the fix.
- The same test or check passes after the fix.
- The final report names the test file and exact command run.
