test: add some tests

[wu8685]

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

• N
• Y

2. What is the scope of this PR (e.g. component or file name):

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Other

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

• N
• Y

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

• Unit test
• Integration test
• Benchmark (add benchmark stats below)
• Manual test (add detailed scripts or steps below)
• Other

6. Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (412b4f2) 46.17% compared to head (a3411f9) 59.67%.

Files	Patch %	Lines
pkg/controllers/collaset/collaset_controller.go	50.00%	0 Missing and 1 partial ⚠️
...lers/podopslifecycle/podopslifecycle_controller.go	50.00%	1 Missing ⚠️
...rver/generic/collaset/collaset_mutating_handler.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #121       +/-   ##
===========================================
+ Coverage   46.17%   59.67%   +13.49%     
===========================================
  Files          45       46        +1     
  Lines        3558     3489       -69     
===========================================
+ Hits         1643     2082      +439     
+ Misses       1700     1188      -512     
- Partials      215      219        +4     

Flag	Coverage Δ
unittests	59.67% <81.25%> (+13.49%)	⬆️

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