css/script/test-deprecations

#!/usr/bin/env node
const fetch = require('node-fetch')
const {versionDeprecations} = require('../deprecations')
const X = '𐄂'
const V = '✓'

checkDeprecations()

async function checkDeprecations() {
  const currentVersion = require('../package.json').version
  const statsPath = 'dist/stats/primer.json'

  const local = require(`../${statsPath}`)
  const remote = await fetch(`https://unpkg.com/@primer/css/${statsPath}`).then(res => res.json())

  const {added, removed} = diffLists(local.selectors.values, remote.selectors.values)
  console.log(`${removed.length} selectors removed: ${removed.join(', ')}`)

  const deprecatedSelectors = []
  const deprecations = versionDeprecations[currentVersion] || []
  const errors = []
  for (const deprecation of deprecations) {
    for (const selector of deprecation.selectors) {
      if (!removed.includes(selector)) {
        const error = `"${selector}" has *not* been removed`
        errors.push(error)
        console.log(`${X} ${error}`)
      } else {
        console.log(`${V} "${selector}" is deprecated!`)
      }
      deprecatedSelectors.push(selector)
    }
  }

  console.log(`${deprecatedSelectors.length} selectors deprecated: ${deprecatedSelectors.join(', ')}`)
  for (const removedSelector of removed) {
    console.log(`checking removed selector "${removedSelector}"...`)
    if (!deprecatedSelectors.includes(removedSelector)) {
      const error = `"${removedSelector}" has been removed, but was not listed in versionDeprecations['${currentVersion}']`
      errors.push(error)
      console.log(`${X} ${error}`)
    } else {
      console.log(`${V} "${removedSelector}" removed and deprecated!`)
    }
  }

  if (errors.length) {
    process.exitCode = 1
  }
}

function diffLists(listA, listB) {
  const setA = new Set(listA)
  const setB = new Set(listB)
  const added = listB.filter(value => !setA.has(value))
  const removed = listA.filter(value => !setB.has(value))
  console.warn(`${added.length} added, ${removed.length} removed`)
  return {
    changed: added.length + removed.length,
    added,
    removed
  }
}