Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Sample controller tests
**What this PR does / why we need it**:
This PR adds unit tests to sample-controller.
**Special notes for your reviewer**:
This is currently based on the munnerz:sample-controller branch. Please don't merged it until #52753 is merged.
Kubernetes-commit: dc20badcd49e5fd2ab41d4320c9c70a50d30343c