test(ui): add Alert component test cases

[aaronlamz]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our Commit Message Guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:
• Test

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

[github-actions]

Website preview has been generated! 🎉 🎉 🎉

[codecov]

Codecov Report

Merging #282 (ded4820) into main (22034a6) will increase coverage by 100.00%.
Report is 469 commits behind head on main.
The diff coverage is n/a.

Additional details and impacted files

@@             Coverage Diff             @@
##           main      #282        +/-   ##
===========================================
+ Coverage      0   100.00%   +100.00%     
===========================================
  Files         0         2         +2     
  Lines         0        54        +54     
  Branches      0        20        +20     
===========================================
+ Hits          0        54        +54     

see 2 files with indirect coverage changes

[xiejay97]

提交的时候，可以 rebase 一下 commit 记录， 保持整洁。

[aaronlamz]

提交的时候，可以 rebase 一下 commit 记录， 保持整洁。
了解，合并忘了选合并方式了