Fix symlink resolving for examples in the repo

Summary:
Motivation:
Few days ago gaearon [filed an issue](https://github.com/facebook/react-native/issues/12406) that examples in the react-native repo doesn't work after the [recent changes in local-cli](bce6ece5f6). This PR fixes reported bug.

**Test plan (required)**
- No UI changes
- [x] Run UIExplorer from XCode (no package.json in the folder) and check if packager/application runs correctly

cc davidaurelio satya164 grabbou
Closes https://github.com/facebook/react-native/pull/12435

Differential Revision: D4657370

Pulled By: ericvicenti

fbshipit-source-id: 72ee4b96cae37c7ed2794ed4490ce7b4fbbd66c3

local-cli/core/default.config.js

@@ -12,21 +12,29 @@
 
 const path = require('path');
 const flatten = require('lodash').flatten;
-
 const blacklist = require('../../packager/blacklist');
-
 const android = require('./android');
 const findAssets = require('./findAssets');
 const ios = require('./ios');
 const windows = require('./windows');
 const wrapCommands = require('./wrapCommands');
 const findPlugins = require('./findPlugins');
-
 const findSymlinksPaths = require('../util/findSymlinksPaths');
-const NODE_MODULES = path.resolve(__dirname, '..', '..', '..');
 
 import type {ConfigT} from './index';
 
+function getProjectPath() {
+  if (__dirname.match(/node_modules[\/\\]react-native[\/\\]local-cli[\/\\]core$/)) {
+    // Packager is running from node_modules.
+    // This is the default case for all projects created using 'react-native init'.
+    return path.resolve(__dirname, '../../../..');
+  } else if (__dirname.match(/Pods[\/\\]React[\/\\]packager$/)) {
+    // React Native was installed using CocoaPods.
+    return path.resolve(__dirname, '../../../..');
+  }
+  return path.resolve(__dirname, '../..');
+}
+
 const getRNPMConfig = (folder) =>
   // $FlowFixMe non-literal require
   require(path.join(folder, './package.json')).rnpm || {};
@@ -35,8 +43,13 @@ const attachPackage = (command, pkg) => Array.isArray(command)
   ? command.map(cmd => attachPackage(cmd, pkg))
   : { ...command, pkg };
 
-const addSymlinkToRoots = (roots) =>
+const resolveSymlink = (roots) =>
-  roots.concat(findSymlinksPaths(NODE_MODULES, roots));
+  roots.concat(
+    findSymlinksPaths(
+      path.join(getProjectPath(), 'node_modules'),
+      roots
+    )
+  );
 
 /**
  * Default configuration for the CLI.
@@ -103,21 +116,10 @@ const config: ConfigT = {
   getProjectRoots() {
     const root = process.env.REACT_NATIVE_APP_ROOT;
     if (root) {
-      return addSymlinkToRoots([path.resolve(root)]);
+      return resolveSymlink([path.resolve(root)]);
     }
 
-    var roots;
+    return resolveSymlink([getProjectPath()]);
-    if (__dirname.match(/node_modules[\/\\]react-native[\/\\]local-cli[\/\\]core$/)) {
-      // Packager is running from node_modules.
-      // This is the default case for all projects created using 'react-native init'.
-      roots = [path.resolve(__dirname, '../../../..')];
-    } else if (__dirname.match(/Pods[\/\\]React[\/\\]packager$/)) {
-      // React Native was installed using CocoaPods.
-      roots = [path.resolve(__dirname, '../../../..')];
-    } else {
-      roots = [path.resolve(__dirname, '../..')];
-    }
-    return addSymlinkToRoots(roots);
   },
 };