### What would you like to be added?

https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/client-go/tools/cache/listers.go has no unit tests, it would be good to have some.

### Why is this needed?

Ensure expected behaviour is checked and preserved.
Add unit tests to client-go/tools/cache/listers.go
This is a GitHub Issue
repo:kubernetes
owner:kubernetes
Title : Add unit tests to client-go/tools/cache/listers.go
Issue date:

--- start body ---
### What would you like to be added?

https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/client-go/tools/cache/listers.go has no unit tests, it would be good to have some.

### Why is this needed?

Ensure expected behaviour is checked and preserved.
--- end body ---
