Testing microservices requires different strategies than monolithic applications. This guide covers testing patterns from unit tests to production verification.
The Testing Pyramid for Microservices
┌───────────────┐
│ E2E Tests │ Few, slow, expensive
├───────────────┤
│ Contract │
│ Tests │ Verify service contracts
├───────────────┤
│ Integration │
│ Tests │ Test with real dependencies
├───────────────┤
│ Component │
│ Tests │ Test service in isolation
├───────────────┤
│ Unit Tests │ Many, fast, cheap
└───────────────┘
Unit Testing
Test business logic in isolation:
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Component Testing
Test a service with its direct dependencies:
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Contract Testing with Pact
Consumer Side
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Provider Side
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Integration Testing
Test service interactions with real dependencies:
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Using Testcontainers
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End-to-End Testing
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Testing Strategies
Chaos Testing
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Best Practices
- Test at the right level: Most tests should be unit/component tests
- Use contract tests: Catch breaking changes early
- Test failure modes: Services will fail, test handling
- Parallelize tests: Use containers for isolation
- Mock external services: Don't depend on third parties in CI
Conclusion
Testing microservices requires a layered approach. Start with unit tests for business logic, use contract tests for service boundaries, and reserve E2E tests for critical user journeys.