What is the role of continuous testing in CI/CD pipelines?

Even in agile products, "traditional" testing often had dedicated periods of time set aside for different activities. For example, you may choose to run regression tests once a sprint on an environment which feature all of the new fixes and functionality that were delivered in that sprint. In continuous testing, test suites are designed and implemented to be run as part of the CI/CD pipeline process. Therefore these tests are run every time the pipelines are run. Therefore, compared to the above situation, the tests would be run multiple times in a sprint, specific to the code that's being pushed. This makes feedback quicker and more specific. It also empowers devs to review tests themselves and address issues before involving a tester.

Continuous Testing in CI tools minimizes the risks involved in releasing new updates and features by embedding frequent and early testing within the development cycle. This practice confirms that newly added code melds seamlessly with the established codebase without giving rise to additional problems. What's also noteworthy is - Continuous Testing epitomizes the "shift-left" tactic, initiating testing at earlier stages in the software development lifecycle. This proactive strategy aids in detecting and addressing defects promptly, preventing them from escalating into more significant issues.

Implementing continuous testing in CI/CD pipelines brings numerous benefits, but it also presents certain challenges. Here is one common challenge associated with continuous testing that I faced: Test Suite Maintenance: As the codebase evolves, maintaining and updating the test suite can become challenging. Test scripts may require frequent updates to accommodate changes in the application's functionality, user interface, or underlying technologies. Ensuring the test suite remains up-to-date and aligned with the application can be time-consuming.

Test suites in the pipeline need to be carefully curated. They should serve a purpose and be as efficient as they can be. It can be easy to write too many tests, or create cumbersome e2e tests that take a long time to execute and re-run. Continuous testing also cannot replace certain test phases (like exploratory testing) and works best with test suites that focus on confirmation and regression testing. As the system under test evolves and grows, automated tests in the CI/CD pipeline will need to be reviewed and maintained. The changes may cause false-errors, which conversely may actually push development to be less efficient as resources are dedicated to debugging where there was a gap in maintenance.

Implementing continuous testing is an iterative process. Start with a solid foundation of automated tests and gradually enhance the testing practices as your CI/CD pipeline matures. By integrating continuous testing into your CI/CD pipeline, you can achieve faster feedback, higher quality software, and increased confidence in your deployments.

Some final things to consider is the increased frequency of test execution in continuous testing can lengthen overall test cycles, potentially slowing development. Techniques like test parallelization and optimization are important to offset the accumulated time spent running tests. Secondly and the final thing is testing early and unfinished code can produce false test failures as the code is still under development. It's important to align on what aspects to focus test automation on for evolving code.