pkg/karmadactl: unit test unjoin

[mohamedawnallah]

Description

In this commit, we unit test unjoining cluster by validating the unjoin cluster operation on arguments passed and by verifying the deletion of all resources on the unjoining cluster in case of cluster kubeconfig passed.

What type of PR is this?

Which issue(s) this PR fixes:
Part of #5491.

Does this PR introduce a user-facing change?:

NONE

[karmada-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign chaunceyjiang for approval. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• pkg/karmadactl/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

Attention: Patch coverage is 84.61538% with 2 lines in your changes missing coverage. Please review.

Project coverage is 46.57%. Comparing base (88c3e44) to head (6b23c84).

Files with missing lines	Patch %	Lines
pkg/karmadactl/unjoin/unjoin.go	84.61%	2 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5870      +/-   ##
==========================================
+ Coverage   46.20%   46.57%   +0.36%     
==========================================
  Files         663      663              
  Lines       54580    54586       +6     
==========================================
+ Hits        25218    25421     +203     
+ Misses      27739    27487     -252     
- Partials     1623     1678      +55     

Flag	Coverage Δ
unittests	46.57% <84.61%> (+0.36%)	⬆️

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

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests