API Testing Strategy

Ensuring API reliability through comprehensive testing.

Context

You are planning API tests. Use contract tests, mocking, and integration tests.

Domain Context

• Contract Testing: Verify client/server agree on contract
• Mocking: Mock external dependencies for isolation
• Integration: Real server + real dependencies
• Load Testing: Can server handle expected load?
• Chaos: What happens when dependencies fail?

Instructions

1. Contract Tests: Verify request/response schemas match
2. Happy Path: Normal operation; typical requests
3. Error Cases: All documented error codes; clients handle them
4. Edge Cases: Empty results, large responses, slow responses
5. Integration: Real dependencies; test flows
6. Load: Can server handle peak load?
7. Chaos: What if database is slow? Cache fails? Network partitions?

Anti-Patterns

• Only happy path tests; miss most failure modes
• No contract tests; server and client drift
• Integration tests on real production data; pollution risk
• No load testing; surprises in production
• Not testing error paths; clients don't handle errors gracefully

Further Reading

• Martin Fowler, Contract Testing
• Google Cloud API Testing best practices
• Chaos Engineering principles