Integration tests verify that different parts of your system work together correctly. They catch issues that unit tests miss—configuration problems, database interactions, and API contracts.
Unit vs Integration Tests
Unit Tests:
- Test single functions/classes
- Mock all dependencies
- Fast (< 10ms each)
- Run frequently
Integration Tests:
- Test multiple components together
- Real databases, APIs, services
- Slower (100ms - 5s each)
- Run before deployment
API Integration Tests
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Database Integration Tests
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Test Database Setup
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External Service Mocking
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Docker Test Environment
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Test Fixtures
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CI Pipeline
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Conclusion
Integration tests are your safety net for system behavior. They catch real bugs that unit tests miss—database constraints, API contracts, and configuration issues.
Invest in a fast, reliable test database setup, and run integration tests before every deployment.