feat: add how to write unit tests

[lightClouds917]

What is the purpose of the change

add how to write unit tests .md

843

除了2篇how to write unit tests .md之外，其他的都是处理冲突导致空格格式变化，可以忽略。

Brief changelog

XXXXX

Follow this checklist to help us incorporate your contribution quickly and easily:

• [x] Make sure there is a GITHUB_issue filed for the change(usually before you start working on it). Trivial changes such as typos do not necessitate a GITHUB issue. Your pull request should solely focus on addressing this specific issue without incorporating any other modifications. Each PR should resolve a single issue.
• [ ] Format the pull request title like doc: add an operations guide document. Each commit within the pull request should contain a meaningful subject line and body.
• [ ] Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• [ ] Test your code locally by running npm run build, and make sure it works as expected.
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[lightClouds917]

中文review check没问题后，再翻译英文。