Merge pull request #8788 from atom/mb-railcar-script

Add railcar script

script/railcar

@@ -0,0 +1,89 @@
+#!/usr/bin/env node
+
+var fs = require('fs')
+var exec = require('child_process').exec
+var series = require('async').series
+var semver = require('semver')
+
+series([
+  section('Preparing to roll the railcars'),
+  checkCleanWorkingTree,
+  run('git fetch origin master:master beta:beta stable:stable'),
+  run('git fetch origin --tags'),
+
+  section('Updating stable branch'),
+  run('git checkout stable'),
+  run('git merge --ff-only origin/stable'),
+  run('git merge --ff-only origin/beta'),
+  bumpStableVersion,
+
+  section('Updating beta branch'),
+  run('git checkout beta'),
+  run('git merge --ff-only origin/beta'),
+  run('git merge --ff-only origin/master'),
+  run('git merge --strategy ours origin/stable'),
+  bumpBetaVersion,
+
+  section('Updating master branch'),
+  run('git checkout master'),
+  run('git merge --ff-only origin/master'),
+  run('git merge --strategy ours origin/beta'),
+  bumpDevVersion,
+
+  section('Pushing changes upstream'),
+  run('git push origin master:master beta:beta stable:stable'),
+  run('git push origin --tags')
+], finish)
+
+function checkCleanWorkingTree (next) {
+  run('git status --porcelain')(function (error, output) {
+    if (error) return next(error)
+    if (output.trim().length > 0) return next(new Error('Cannot run the railcars with a dirty working tree'))
+    next()
+  })
+}
+
+function bumpStableVersion (next) {
+  run('npm version patch')(next)
+}
+
+function bumpBetaVersion (next) {
+  var newVersion = semver.inc(getCurrentVersion(), 'prerelease', 'beta')
+  run('npm version ' + newVersion)(next)
+}
+
+function bumpDevVersion (next) {
+  var newVersion = semver.inc(getCurrentVersion(), 'preminor', 'dev')
+  series([
+    run('npm --no-git-tag-version version ' + newVersion),
+    run('git commit -am "' + newVersion + '"')
+  ], next)
+}
+
+function finish (error) {
+  if (error) {
+    console.log('Error: ' + error.message)
+    process.exit(1)
+  }
+
+  console.log('OK, now just wait for all CI builds to pass on beta and stable')
+}
+
+function getCurrentVersion () {
+  return JSON.parse(fs.readFileSync(require.resolve('../package.json'))).version
+}
+
+function run (command) {
+  return function (next) {
+    console.log('>', command)
+    exec(command, next)
+  }
+}
+
+function section (message) {
+  return function (next) {
+    console.log()
+    console.log(message)
+    next()
+  }
+}