/ˌɪn.tɪˈɡreɪ.ʃən ˈtɛs.tɪŋ/
noun — "finding out which pieces break when they finally have to talk to each other."
Integration Testing is a software testing practice that verifies how individual units or components work together as a group. While unit tests focus on isolated code, integration testing examines the interactions between modules, services, or systems to ensure data flows and dependencies behave correctly.
Technically, Integration Testing targets boundaries between components. This includes interfaces, APIs, databases, file systems, and external services. It helps uncover issues such as incorrect assumptions, mismatched data formats, timing problems, or configuration errors that are invisible during isolated testing.
Integration tests are often executed after Unit Testing and before full system or end-to-end testing. They may use real dependencies or controlled substitutes such as mocks and stubs, depending on the test scope and environment.
In practice, Integration Testing is essential for detecting failures related to Runtime behavior, network communication, and shared resources. Many production bugs originate not from broken logic, but from components that individually work fine yet fail when combined.
Conceptually, Integration Testing is the first reality check. It answers the question: “Do these parts actually work together, or were they just being polite in isolation?”
Integration Testing supports reliable releases by validating real-world interactions and complements broader quality efforts alongside Testing, Debugging, and exception handling mechanisms like Try-Catch.
See Unit Testing, Testing, Debugging, Runtime, Try-Catch.