Increase test coverage in operator/pkg/version (#22450)
Increase test coverage in operator/pkg/version (#22450)

* Extend test coverage for UnmarshalYAML

* Add test cases for GetVersionCompatibleMap

The coverage is up to 91% now

* Add TestUnmarshalYAML to force unmarshal fail

This is only to test the code coverage, uncertain how helpful this is

* Add test coverage on Stringer interface

* Remove unnecessary comment, rename closer func
smawson/istio,istio/istio,smawson/istio,smawson/istio,istio/istio,smawson/istio,istio/istio,istio/istio,smawson/istio,istio/istio,smawson/istio