extract parent folder name matcher to its own module and add tests

Author: chrisvfritz

helpers/parent-folder-name-for.js

@@ -0,0 +1,3 @@
+module.exports = function (file) {
+  return file.match(/([^\/\\]+)[\/\\][^\/\\]+\.js/)[1]
+}

helpers/parent-folder-name-for.spec.js

@@ -0,0 +1,17 @@
+'use strict'
+
+const getParentFolderName = require('./parent-folder-name-for')
+
+describe('Helper: parent-folder-name-for', () => {
+  it('returns the main migration guide for vue', () => {
+    expect(
+      getParentFolderName('/Users/fritzc/code/vue-migration-helper/rules/vue/array-prototype-remove.js')
+    ).toBe('vue')
+  })
+
+  it('returns the main migration guide for vue', () => {
+    expect(
+      getParentFolderName('C:\\Users\\fuis\\AppData\\Roaming\\npm\\node_modules\\vue-migration-helper\\rules\\vue\\array-prototype-remove.js')
+    ).toBe('vue')
+  })
+})

helpers/report-warning.js

@@ -2,12 +2,13 @@
 
 var chalk = require('chalk')
 var migrationGuideUrlFor = require('./migration-guide-url-for')
+var parentFolderNameFor = require('./parent-folder-name-for')
 
 var warningCount = 0
 module.exports = function (fileData, warning, rule) {
   warningCount++
 
-  var library = rule.file.match(/([^\/\\]+)[\/\\][^\/\\]+\.js/)[1]
+  var library = parentFolderNameFor(rule.file)
 
   console.log()
   console.log(chalk.yellow(