fix(helpers): call url_for from hexo-util

[curbengh]

What does it do?

const css = hexo.extend.helper.get('css').bind(hexo)
const css = hexo.extend.helper.get('css')

doesn't work for me, somehow url_for() is not available in the hexo context. I tried v4.0.0, v4.1.1, v4.2.1 & v5 in Node 12.18

How to test

git clone -b url_for 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.

[coveralls]

Coverage increased (+0.003%) to 98.239% when pulling 0fb3e31 on curbengh:url_for into 1489074 on hexojs:master.

[stevenjoezhang]

this.url_for is only available in another helper, e.g.

https://github.com/next-theme/hexo-theme-next/blob/v8.0.0-rc.4/scripts/helpers/next-url.js#L16

https://github.com/next-theme/hexo-theme-next/blob/test/test/helpers/next-url.js#L16

[SukkaW]

Should we replace all this.url_for in helpers?

[curbengh]

Should we replace all this.url_for in helpers?

we should. updating PR... (Edit) done

hexo.extend.helper.get('css').bind(hexo) or hexo.extend.helper.get('css') also don't work for you?

[SukkaW]

LGTM!

Anyway, is there any this.full_url_for exists as well? If so, it could be replaced as well.

[curbengh]

Anyway, is there any this.full_url_for exists as well?

That's all I found with vscode.

[SukkaW]

LGTM!