Case study · Fintech · Go/TypeScript · 3 months
Fintech API — Coverage Up 32%
Contract and golden tests reduced incidents and supported faster iteration.
Context
- Multiple downstream consumers with undocumented API behavior and breaking changes.
- Long triage cycles with insufficient observability around error causes.
Actions
- Added provider/consumer contract tests and golden tests for critical flows.
- Implemented structured logging and tracing to shorten MTTD.
- CI gated on contract validation; published API examples for partners.
Results
- Statement generation incidents down 24%.
- P99 latency improved 18% after removing synchronous IO in hot paths.
- Developer onboarding time decreased with living API docs.
+32%
Test coverage
-24%
Incidents
-18%
P99 latency