Introduction to Quality Assurance: Why Functional Testing Matters Functional testing is critical to quality assurance. Identifying and correcting errors pre-release helps ensure the reliability and stability of APIs and web services as well as build confidence among your key stakeholders.  Integration testing bridges the gap between unit testing and software testing, helping your team test potential side effects before they become big-time issues. Even if individual modules are successfully unit tested, errors may still exist after integration. By analyzing multiple parts of...