Ensuring your Kubernetes component, such as a controller or an operator, works correctly is an important step before merging a pull request or deploying it to the production. You want to be sure that incoming changes will not introduce any regression or negatively effect any part of the system. This is usually done by running integration and end-to-end tests in the CI/CD pipeline. They test the component on all incoming changes, automatically and in a clean environment, and thereby prevent potential errors and flakes.
This is a companion discussion topic for the original entry at https://www.kubermatic.com/blog/2019-03-12-running-kubernetes-in-the-ci-pipeline-/