[feature request] Adding unit test case for modifyResponse function in Yurthub

[rambohe-ch]

What would you like to be added:
As discussed in the pull request #794 , I's more reliable to add some unit test case for modifyResponse function in yurthub. the code reference link is here: https://github.com/openyurtio/openyurt/blob/master/pkg/yurthub/proxy/remote/remote.go#L128-L203

Why is this needed:
modifyResponse function is entry for data filtering framework and local cache manager, so we need to make sure the stability for this function.

others
/kind feature

[xavier-hou]

I have some questions here.

1. I found that modifyResponse invokes some other functions, such as cachemanager.CacheResponse, which I guess might depend on specific storage. I would like to know if there is any way to test its correctness.
2. Besides, I think some "local variables" such as resp.Request need to be tested as well since they are modified inside the function and seem to be cached. I found this difficult to cover with unit test.

Can anyone give me some advice?

[Congrool]

It seems that we;ve already had the test of cachemanaer.CacheResponse in pkg/yurthub/cache_manager_test.go, so here we can foucus on modifyResponse itself.

How about write a fake cacheManager to instead? @HXCGIT

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[rambohe-ch]

/assign @rambohe-ch