test: comment out missing tests

[curbengh]

What does it do?

Not very keen on 'x pending' message at the end of unit test.
I added "missing-unit-test" to the comment. We can mention it in the roadmap, and contributor can simply search for the keyword to locate missing tests.

Add a missing test for list_archives helper.
load_database test is being worked on #3975

Revert #3742

How to test

git clone -b test-missing https://github.com/curbengh/hexo.git
cd hexo
npm install
npm test

Screenshots

Pull request tasks

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

[curbengh]

Instead of using x pending to show missing test, I suggest to add a note, like

// it('deployer not found'); missing-unit-test

Then we can mention it in the roadmap, and contributor can simply search for "missing-unit-test" to locate missing tests.

[coveralls]

Coverage remained the same at 97.137% when pulling f5a7b1f on curbengh:test-missing into c82082c on hexojs:master.

[coveralls]

Coverage remained the same at 97.137% when pulling caf41c4 on curbengh:test-missing into c82082c on hexojs:master.

[curbengh]

#3975