Integration Testing
Definition
An integration test checks whether multiple components or systems work correctly together at their interfaces.
Unlike unit testing, the focus is on interaction: data formats, APIs, databases, queues, authentication, and error cases between components are tested together.
Simply explained
How not only to test individual machine parts but whether they function correctly together.
Why it matters in practice
Highly relevant for automations and web applications with multiple APIs, data sources, or services.
Example from business
A test checks whether a form correctly passes data to API, CRM, and confirmation service and handles errors cleanly.
Limits and pitfalls
- Only testing the happy path; mocking external services without verification; not isolating test data; equating integration testing with full end-to-end testing.
Origin & history
Integration testing is an established software quality test level and is clearly distinguished from unit and system tests in test standards and curricula.
Use in mid-sized companies
- Possible applications: API chains, data pipelines, CRM integrations, webhooks, and AI workflows.
Frequently asked questions
What is the difference from unit testing?
Integration tests check the interaction of multiple units. Must every external service be live? Not necessarily; test strategy and risk determine this.
Sources
- Integration Testing · ISTQB Glossary, Integration Testing
Sources verified on 10.10.2026.
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