test: add test cases for yurthub

[donychen1134]

What type of PR is this?

/kind enhancement

What this PR does / why we need it:

add unit test cases for yurthub

Which issue(s) this PR fixes:

Fixes #917

Special notes for your reviewer:

Does this PR introduce a user-facing change?

other Note

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In response to this:

What type of PR is this?

/kind enhancement

What this PR does / why we need it:

add unit test cases for yurthub

Which issue(s) this PR fixes:

Fixes #917

Special notes for your reviewer:

Does this PR introduce a user-facing change?

other Note

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[codecov]

Codecov Report

Merging #972 (09b901b) into master (fd0d3d3) will increase coverage by 0.83%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #972      +/-   ##
==========================================
+ Coverage   44.38%   45.22%   +0.83%     
==========================================
  Files          83       85       +2     
  Lines       11370    11857     +487     
==========================================
+ Hits         5047     5362     +315     
- Misses       5886     6047     +161     
- Partials      437      448      +11     

Flag	Coverage Δ
unittests	45.22% <100.00%> (+0.83%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/yurthub/util/connrotation.go	86.48% <ø> (+86.48%)	⬆️
pkg/yurthub/util/util.go	77.93% <100.00%> (+56.55%)	⬆️
pkg/yurthub/certificate/hubself/cert_mgr.go	20.04% <0.00%> (ø)
pkg/yurthub/certificate/hubself/fake_cert_mgr.go	0.00% <0.00%> (ø)
...troller/nodelifecycle/node_lifecycle_controller.go	56.15% <0.00%> (+0.60%)	⬆️

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[rambohe-ch]

@donychen1134 please fix the golangci-lint errors.

the library import sequence:

1. golang libs
2. k8s.io and github libs
3. openyurt libs

[rambohe-ch]

/lgtm
/approve

[openyurt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: donychen1134, rambohe-ch

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