Adding jest and jest babel preset to the react-native init command

Summary:
Adding jest and its presets to the react-native init command

**Test plan (required)**
run react-native init foo (using `npm link` to use the local `react-native` version)
inside foo there are now a .babelrc file and the package.json is set up as described by
https://facebook.github.io/jest/docs/tutorial-react-native.html#setup
Closes https://github.com/facebook/react-native/pull/9719

Differential Revision: D3843037

Pulled By: bestander

fbshipit-source-id: 004e27ebd3f257a202ed43f378d6fe6cc23ced52

local-cli/generator/index.js

@@ -8,6 +8,7 @@
  */
 'use strict';
 
+var fs = require('fs');
 var path = require('path');
 var yeoman = require('yeoman-generator');
 var utils = require('../generator-utils');
@@ -15,7 +16,6 @@ var utils = require('../generator-utils');
 module.exports = yeoman.generators.NamedBase.extend({
   constructor: function() {
     yeoman.generators.NamedBase.apply(this, arguments);
-
     this.option('skip-ios', {
       desc: 'Skip generating iOS files',
       type: Boolean,
@@ -26,6 +26,11 @@ module.exports = yeoman.generators.NamedBase.extend({
       type: Boolean,
       defaults: false
     });
+    this.option('skip-jest', {
+      desc: 'Skip installing Jest',
+      type: Boolean,
+      defaults: false
+    });
     this.option('upgrade', {
       desc: 'Specify an upgrade',
       type: Boolean,
@@ -108,5 +113,41 @@ module.exports = yeoman.generators.NamedBase.extend({
     }
 
     this.npmInstall(`react@${reactVersion}`, { '--save': true, '--save-exact': true });
+    if (!this.options['skip-jest']) {
+      this.npmInstall(`jest babel-jest jest-react-native babel-preset-react-native react-test-renderer@${reactVersion}`.split(' '), {
+        saveDev: true,
+        '--save-exact': true
+      });
+      fs.writeFileSync(
+        path.join(
+          this.destinationRoot(),
+          '.babelrc'
+        ),
+        '{\n"presets": ["react-native"]\n}'
+      );
+
+      this.fs.copy(
+        this.templatePath('__tests__'),
+        this.destinationPath('__tests__'),
+        {
+          nodir: false
+        }
+      );
+
+      var packageJSONPath = path.join(
+        this.destinationRoot(),
+        'package.json'
+      );
+      var packageJSON = JSON.parse(
+        fs.readFileSync(
+          packageJSONPath
+        )
+      );
+      packageJSON.scripts.test = 'jest';
+      packageJSON.jest = {
+        preset: 'jest-react-native'
+      };
+      fs.writeFileSync(packageJSONPath, JSON.stringify(packageJSON, null, '\t'));
+    }
   }
 });

local-cli/generator/templates/__tests__/index.android.js

@@ -0,0 +1,12 @@
+import 'react-native';
+import React from 'react';
+import Index from '../index.android.js';
+
+// Note: test renderer must be required after react-native.
+import renderer from 'react-test-renderer';
+
+it('renders correctly', () => {
+  const tree = renderer.create(
+    <Index />
+  );
+});

local-cli/generator/templates/__tests__/index.ios.js

@@ -0,0 +1,12 @@
+import 'react-native';
+import React from 'react';
+import Index from '../index.ios.js';
+
+// Note: test renderer must be required after react-native.
+import renderer from 'react-test-renderer';
+
+it('renders correctly', () => {
+  const tree = renderer.create(
+    <Index />
+  );
+});

local-cli/generator/templates/index.android.js

@@ -12,7 +12,7 @@ import {
   View
 } from 'react-native';
 
-class <%= name %> extends Component {
+export default class <%= name %> extends Component {
   render() {
     return (
       <View style={styles.container}>

local-cli/generator/templates/index.ios.js

@@ -12,7 +12,7 @@ import {
   View
 } from 'react-native';
 
-class <%= name %> extends Component {
+export default class <%= name %> extends Component {
   render() {
     return (
       <View style={styles.container}>

package.json

@@ -23,7 +23,8 @@
       "^[./a-zA-Z0-9$_-]+\\.png$": "RelativeImageStub"
     },
     "testPathIgnorePatterns": [
-      "/node_modules/"
+      "/node_modules/",
+      "local-cli/generator/templates/"
     ],
     "haste": {
       "defaultPlatform": "ios",

scripts/run-ci-e2e-tests.js

@@ -200,6 +200,11 @@ try {
       exitCode = 1;
       throw Error(exitCode);
     }
+    if (exec(`npm test`).code) {
+      echo('Jest test failure');
+      exitCode = 1;
+      throw Error(exitCode);
+    }
   }
   exitCode = 0;