integrationtest

An integration test, sometimes called an integrationtest, is a software testing level focused on verifying that multiple components or systems work together as intended. Unlike unit tests that validate a single component in isolation, integration tests exercise the interfaces and data flows between modules, services, databases, and external dependencies.

By testing interactions, integration tests aim to detect interface mismatches, incorrect data formats, and integration errors that unit tests cannot reveal.

Approaches include incremental strategies such as top-down or bottom-up integration, as well as the big bang approach. In incremental approaches, selected components are integrated stepwise with stubs or drivers to simulate incomplete parts. In big bang, all parts are integrated at once.

Common practices include defining clear interface contracts, using test doubles (stubs, mocks) when external systems are unavailable, creating representative test data, running in a dedicated environment, automating in continuous integration pipelines, and keeping tests deterministic and fast.

Tools and frameworks for integration testing vary by language but often include Java tools like JUnit or TestNG, Python tools like pytest, and JavaScript tools like Jest or Mocha. API-focused tests may use specialized libraries such as REST-assured or similar HTTP clients to validate service interactions.

Limitations of integration tests include sensitivity to changes in interfaces or environment setup, potential flakiness, and longer execution times compared with unit tests. They require careful data management and environment control to remain reliable and maintainable.

Overall, integration testing helps verify that the system behaves correctly when components interact, providing earlier detection of integration issues and better documentation of interfaces and data contracts.