Executing unit, integration, and end-to-end tests within the CI pipeline.
Automated testing is the quality assurance backbone of CI/CD. It provides the confidence needed to release software frequently and reliably. There are several layers of automated testing, each serving a different purpose. Unit Tests are the most granular, testing individual functions or components of the code in isolation. They are fast to run and help developers pinpoint defects at a very low level. Integration Tests verify that different parts of the application work together as expected. For example, they might test the interaction between an API endpoint and a database. End-to-End (E2E) Tests simulate a full user journey through the application, from the user interface down to the backend services. They are the most comprehensive but also the slowest and most complex to maintain. A mature CI pipeline incorporates a strategy that balances these testing types. On every commit, the fast-running unit tests are executed to provide immediate feedback. Integration and E2E tests might be run less frequently, for instance, on pull requests or nightly builds. By embedding these automated checks directly into the pipeline, teams can catch regressions and bugs automatically before they ever reach production, creating a crucial safety net that enables developers to code with confidence and speed.