Refactor(test): Useful sinon.assert

[segayuu]

What does it do?

How to test

git clone -b BRANCH https://github.com/USER/hexo.git
cd hexo
npm install
npm test

Screenshots

Pull request tasks

• Add test cases for the changes.
• Passed the CI test.

[SukkaW]

IMHO, since Hexo has complicate unit tests, it is better to retain test/index.js. Also, using * might causes different behaviors between enviroments.