Make the CLI recognize CRNA projects

Summary:
1. Make running `react-native run-ios` or `react-native run-android`
inside a project created with Create React Native App run the
corresponding react-native-scripts command instead of failing.

    **Before**:
    <img width="762" alt="screen shot 2017-07-21 at 16 55 32" src="https://user-images.githubusercontent.com/497214/28467425-86b309c8-6e38-11e7-8946-139bda927d93.png"><img width="762" alt="screen shot 2017-07-21 at 16 55 52" src="https://user-images.githubusercontent.com/497214/28467436-8df02482-6e38-11e7-8a03-3fa664944cac.png">
    **After**:
    <img width="762" alt="screen shot 2017-07-21 at 16 52 15" src="https://user-images.githubusercontent.com/497214/28467522-e4bb6cae-6e38-11e7-97bb-9cfa9cb4dc67.png">

2. Make running `react-native link` inside a CRNA project display a
helpful error message.

    **Before**:
    <img width="762" alt="screen shot 2017-07-21 at 16 55 10" src="https://user-images.githubusercontent.com/497214/28467608-1d1781fa-6e39-11e7-9620-cc16c8b1b40f.png">
    **After**:
    <img width="762" alt="screen shot 2017-07-21 at 16 53 10" src="https://user-images.githubusercontent.com/497214/28467637-2cd6ed1a-6e39-11e7-8947-6df69b3f321e.png">

Fixes #14828.

* Run `react-native run-ios`, `react-native run-android` and `react-native link` in:
  * A CRNA project (screenshot above)
  * A traditional RN project (existing behaviour)
  * A folder that contains neither (existing behaviour)
Closes facebook/react-native#15139

Differential Revision: D5498914

Pulled By: hramos

fbshipit-source-id: 94b6196e3451857bbaa45335a01643c89bed19a0

Author: fson

link/link.js

@@ -30,6 +30,7 @@ const getDependencyConfig = require('./getDependencyConfig');
 const pollParams = require('./pollParams');
 const commandStub = require('./commandStub');
 const promisify = require('./promisify');
+const findReactNativeScripts = require('../util/findReactNativeScripts');
 
 import type {RNConfig} from '../core';
 
@@ -147,6 +148,16 @@ function link(args: Array<string>, config: RNConfig) {
     return Promise.reject(err);
   }
 
+  if (!project.android && !project.ios && !project.windows && findReactNativeScripts()) {
+    throw new Error(
+      '`react-native link` can not be used in Create React Native App projects. ' +
+      'If you need to include a library that relies on custom native code, ' +
+      'you might have to eject first. ' +
+      'See https://github.com/react-community/create-react-native-app/blob/master/EJECTING.md ' +
+      'for more information.'
+    );
+  }
+
   let packageName = args[0];
   // Check if install package by specific version (eg. package@latest)
   if (packageName !== undefined) {

runAndroid/runAndroid.js

@@ -13,6 +13,7 @@ const chalk = require('chalk');
 const child_process = require('child_process');
 const fs = require('fs');
 const isPackagerRunning = require('../util/isPackagerRunning');
+const findReactNativeScripts = require('../util/findReactNativeScripts');
 const isString = require('lodash/isString');
 const path = require('path');
 const Promise = require('promise');
@@ -27,7 +28,16 @@ function checkAndroid(root) {
  */
 function runAndroid(argv, config, args) {
   if (!checkAndroid(args.root)) {
-    console.log(chalk.red('Android project not found. Maybe run react-native android first?'));
+    const reactNativeScriptsPath = findReactNativeScripts();
+    if (reactNativeScriptsPath) {
+      child_process.spawnSync(
+        reactNativeScriptsPath,
+        ['android'].concat(process.argv.slice(1)),
+        {stdio: 'inherit'}
+      );
+    } else {
+      console.log(chalk.red('Android project not found. Maybe run react-native android first?'));
+    }
     return;
   }
 

runIOS/runIOS.js

@@ -12,13 +12,27 @@ const child_process = require('child_process');
 const fs = require('fs');
 const path = require('path');
 const findXcodeProject = require('./findXcodeProject');
+const findReactNativeScripts = require('../util/findReactNativeScripts');
 const parseIOSDevicesList = require('./parseIOSDevicesList');
 const findMatchingSimulator = require('./findMatchingSimulator');
 const getBuildPath = function(configuration = 'Debug', appName, isDevice) {
   return `build/Build/Products/${configuration}-${isDevice ? 'iphoneos' : 'iphonesimulator'}/${appName}.app`;
 };
 
 function runIOS(argv, config, args) {
+  if (!fs.existsSync(args.projectPath)) {
+    const reactNativeScriptsPath = findReactNativeScripts();
+    if (reactNativeScriptsPath) {
+      child_process.spawnSync(
+        reactNativeScriptsPath,
+        ['ios'].concat(process.argv.slice(1)),
+        {stdio: 'inherit'}
+      );
+      return;
+    } else {
+      throw new Error('iOS project folder not found. Are you sure this is a React Native project?');
+    }
+  }
   process.chdir(args.projectPath);
   const xcodeProject = findXcodeProject(fs.readdirSync('.'));
   if (!xcodeProject) {

util/findReactNativeScripts.js

@@ -0,0 +1,28 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
+ */
+'use strict';
+
+const path = require('path');
+const fs = require('fs');
+
+function findReactNativeScripts(): ?string {
+  const executablePath = path.resolve(
+    'node_modules',
+    '.bin',
+    'react-native-scripts'
+  );
+  if (fs.existsSync(executablePath)) {
+    return executablePath;
+  }
+  return null;
+}
+
+module.exports = findReactNativeScripts;