feat: add ut by tongyilingma and fix some error message

[leossteven]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespace from that line:
/kind bug
/kind documentation
/kind enhancement
/kind good-first-issue
/kind feature
/kind question
/kind design
/sig ai
/sig iot
/sig network
/sig storage

/kind feature

What this PR does / why we need it:

feat: add ut by tongyilingma and fix some error message

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

@rambohe-ch

other Note

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 58.85%. Comparing base (3713163) to head (ea79293).
Report is 32 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2126      +/-   ##
==========================================
+ Coverage   56.09%   58.85%   +2.75%     
==========================================
  Files         186      209      +23     
  Lines       18092    18924     +832     
==========================================
+ Hits        10149    11137     +988     
+ Misses       6910     6706     -204     
- Partials     1033     1081      +48     

Flag	Coverage Δ
unittests	58.85% <100.00%> (+2.75%)	⬆️

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[rambohe-ch]

/LGTM