Testing

Command

yarn test

Tests live in tests/ (Jest configuration per repo defaults).

What to test

Layer	Suggestion
Pure helpers	compute functions, URL builders, parsers — fast, deterministic
Querystring mappers	Edge cases: empty csv, invalid numbers, defaults
Regression bugs	Add a test when fixing a subtle mapping or routing bug

What is harder to test

• Full Lambda + API Gateway integration — usually exercised via deployed dev + automated smoke tests elsewhere.
• Heavy Spark fixtures — prefer recorded snapshots or minimal JSON fixtures checked into tests/ when allowed.

CI

• Pull requests should stay green on yarn test before merge (exact CI job names depend on org setup — align with develop branch protections).

Related

• Lint, format, hooks
• Cookbook: new endpoint