Integration Testing

Definitions

1. Integration testing verifies that separate components or services work correctly when connected together, catching bugs that emerge only from interactions between modules. These tests sit between unit tests (which test functions in isolation) and end-to-end tests (which simulate full user flows) in the testing pyramid. Typical integration tests verify database queries against a real or containerized database, test API endpoints with actual HTTP requests, or confirm that two microservices communicate correctly over a message queue. They run slower than unit tests because they involve real infrastructure, but they catch an important class of defects: incorrect API contracts, serialization mismatches, transaction handling errors, and configuration problems that mocks would never reveal.

   In plain English: Testing that checks whether different parts of a system work correctly together — because two perfectly working pieces can still fail when connected.

   Example: "Unit tests all passed, but the integration test caught that our API was sending dates in the wrong timezone to the database."

Related Terms

• E2E Testing
• Pure Function
• Flaky Test
• Semantic Commit
• SAST
• Nightly Build
• Matrix Build
• Artifact Registry
• Multi-Arch Build
• Regression Test
• Suite
• Test Harness
• Test Suite
• Testing Pyramid
• Visual Regression Test