lib/rules/pr-url.js

const id = 'pr-url'
const prUrl = /^https:\/\/github\.com\/[\w-]+\/[\w-]+\/pull\/\d+\/?$/

export default {
  id,
  meta: {
    description: 'enforce PR-URL',
    recommended: true
  },
  defaults: {},
  options: {},
  validate: (context, rule) => {
    if (!context.prUrl) {
      context.report({
        id,
        message: 'Commit must have a PR-URL.',
        string: context.prUrl,
        line: 0,
        column: 0,
        level: 'fail'
      })
      return
    }
    let line = -1
    let column = -1
    for (let i = 0; i < context.body.length; i++) {
      const l = context.body[i]
      if (~l.indexOf('PR-URL') && ~l.indexOf(context.prUrl)) {
        line = i
        column = l.indexOf(context.prUrl)
      }
    }
    if (context.prUrl[0] === '#') {
      // see nodejs/node#7d3a7ea0d7df9b6f11df723dec370f49f4f87e99
      // for an example
      context.report({
        id,
        message: 'PR-URL must be a URL, not a pull request number.',
        string: context.prUrl,
        line,
        column,
        level: 'fail'
      })
    } else if (!prUrl.test(context.prUrl)) {
      context.report({
        id,
        message: 'PR-URL must be a GitHub pull request URL.',
        string: context.prUrl,
        line,
        column,
        level: 'fail'
      })
    } else {
      context.report({
        id,
        message: 'PR-URL is valid.',
        string: context.prUrl,
        line,
        column,
        level: 'pass'
      })
    }
  }
}