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.