Allow to require module path from whitelisted dependency

Required module path can be one of

- `fs` (built-in Node.js module),
- `abortcontroller-polyfill` (external main module),
- `abortcontroller-polyfill/dist/cjs-ponyfill` (external submodule).

FastBoot's build system requires only dependency whitelisting,
thus looking only for the first part of module path.

package.json

@@ -30,6 +30,7 @@
     "cookie": "^0.3.1",
     "debug": "^3.0.0",
     "najax": "^1.0.2",
+    "resolve": "^1.8.1",
     "rsvp": "^4.7.0",
     "simple-dom": "^1.0.0",
     "source-map-support": "^0.5.0"

src/ember-app.js

@@ -6,11 +6,13 @@ const chalk = require('chalk');
 
 const najax = require('najax');
 const SimpleDOM = require('simple-dom');
+const resolve = require('resolve');
 const debug = require('debug')('fastboot:ember-app');
 
 const FastBootInfo = require('./fastboot-info');
 const Result = require('./result');
 const FastBootSchemaVersions = require('./fastboot-schema-versions');
+const getPackageName = require('./utils/get-package-name');
 
 /**
  * @private
@@ -116,21 +118,34 @@ class EmberApp {
   buildWhitelistedRequire(whitelist, distPath) {
     whitelist.forEach(function(whitelistedModule) {
       debug("module whitelisted; module=%s", whitelistedModule);
+
+      // Remove after 2.0.0
+      let packageName = getPackageName(whitelistedModule);
+
+      if (packageName !== whitelistedModule) {
+        console.warn("[DEPRECATION] Whitelisting module path '" + whitelistedModule + "' will not be supported after fastboot#2.0.0 and it should be removed from the whitelist.");
+
+        if (whitelist.indexOf(packageName) === -1) {
+          console.error("Package '" + packageName +  "' is required to be in the whitelist.");
+        }
+      }
     });
 
     return function(moduleName) {
-      if (whitelist.indexOf(moduleName) > -1) {
-        let nodeModulesPath = path.join(distPath, 'node_modules', moduleName);
+      let packageName = getPackageName(moduleName);
+      let isWhitelisted = whitelist.indexOf(packageName) > -1;
 
-        if (fs.existsSync(nodeModulesPath)) {
-          return require(nodeModulesPath);
-        } else {
-          // If it's not on disk, assume it's a built-in node package
-          return require(moduleName);
-        }
-      } else {
-        throw new Error("Unable to require module '" + moduleName + "' because it was not in the whitelist.");
+      if (isWhitelisted) {
+        let resolvedModulePath = resolve.sync(moduleName, { basedir: distPath });
+        return require(resolvedModulePath);
+      }
+
+      // Remove after 2.0.0
+      if (whitelist.indexOf(moduleName) > -1) {
+        return require(moduleName);
       }
+
+      throw new Error("Unable to require module '" + moduleName + "' because its package '" + packageName + "' was not in the whitelist.");
     };
   }
 

src/utils/get-package-name.js

@@ -0,0 +1,12 @@
+'use strict';
+
+function getPackageName(modulePath) {
+  let parts = modulePath.split('/');
+
+  if (modulePath[0] === '@') {
+    return parts[0] + '/' + parts[1];
+  }
+  return parts[0];
+}
+
+module.exports = getPackageName;

test/get-package-name-test.js

@@ -0,0 +1,12 @@
+'use strict';
+const expect = require('chai').expect;
+const getPackageName = require('../src/utils/get-package-name');
+
+describe('utils/get-package-name', function() {
+  it('gets package name from module path', function() {
+    expect(getPackageName('foo')).to.equal('foo');
+    expect(getPackageName('foo/bar')).to.equal('foo');
+    expect(getPackageName('@foo/baz')).to.equal('@foo/baz');
+    expect(getPackageName('@foo/baz/bar')).to.equal('@foo/baz');
+  });
+});