Integration testing validates service interactions, database communications, and cross-component workflows in distributed systems. Unlike unit tests that verify isolated logic, integration tests ensure real dependencies work together correctly — catching errors in API contracts, event flows, data persistence, and external service integrations. Critical for microservices, event-driven architectures, and systems requiring reliable inter-service communication, integration testing bridges the gap between fast unit tests and slow end-to-end scenarios by focusing on component boundaries and integration points. Modern patterns emphasize contract-first APIs, isolated test environments, realistic data, and CI-optimized execution to maintain confidence without sacrificing speed.
What This Cheat Sheet Covers
This topic spans 15 focused tables and 92 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.
Table 1: Integration Testing Approaches
| Approach | Example | Description |
|---|---|---|
class FullSystemTest { } | • All modules tested together after development completes • rare in modern practice due to delayed feedback and hard-to-diagnose failures | |
OrderService service | Start testing from UI/API layer, stub lower components as you progress downward | |
Test DatabaseRepository →ServiceLayer →APIController | Begin with foundational modules (data layer), build upward to higher-level components |