feat(init): creates the contributor file if not found (#158)

* feat(init): creates the contributor file if not found

If not found, the specified contributor file (defaulting to `README.md`) will be created prior to
injections in it.

re https://github.com/all-contributors/all-contributors-bot/issues/105

* refactor(init): renamed a module and its export

Renamed `check-file` to `file-exist` and its exported function to `ensureFileExists`

* test(init): added contributors file test

Added two test cases for the contributors file existence check

src/init/__tests__/add-contributors-list.js

@@ -1,4 +1,6 @@
+import {unlink} from 'fs'
 import {addContributorsList} from '../init-content'
+import ensureFileExists from '../file-exist'
 
 test('insert list under contributors section', () => {
   const content = [
@@ -27,3 +29,21 @@ test('create contributors section if content is empty', () => {
 
   expect(result).toMatchSnapshot()
 })
+
+test('README exists', done => {
+  const file = 'README.md'
+  ensureFileExists(file)
+    .then(data => expect(data).toStrictEqual(file))
+    .then(_ => done())
+})
+
+test("LOREM doesn't exists", done => {
+  const file = 'LOREM.md'
+  ensureFileExists(file).then(data => {
+    expect(data).toStrictEqual(file)
+    return unlink(file, err => {
+      if (err) throw err
+      done()
+    })
+  })
+})

src/init/file-exist.js

@@ -0,0 +1,11 @@
+const fs = require('fs')
+
+module.exports = function ensureFileExists(file) {
+  return new Promise((resolve, reject) => {
+    if (fs.existsSync(file)) return resolve(file)
+    fs.writeFile(file, '', err => {
+      if (err) reject(err)
+      resolve(file)
+    })
+  })
+}

src/init/index.js

@@ -1,6 +1,7 @@
 const util = require('../util')
 const prompt = require('./prompt')
 const initContent = require('./init-content')
+const ensureFileExists = require('./file-exist')
 
 const configFile = util.configFile
 const markdown = util.markdown
@@ -13,6 +14,9 @@ module.exports = function init() {
   return prompt().then(result => {
     return configFile
       .writeConfig('.all-contributorsrc', result.config)
+      .then(() => {
+        ensureFileExists(result.contributorFile)
+      })
       .then(() =>
         injectInFile(result.contributorFile, initContent.addContributorsList),
       )