use OS module

Author: lifeart

test/builder_test.js

@@ -17,7 +17,7 @@ import heimdall from 'heimdalljs';
 const multidepRequire = MultidepRequire('test/multidep.json');
 const Plugin = multidepRequire('broccoli-plugin', '1.3.0');
 const broccoliSource = multidepRequire('broccoli-source', '1.1.0');
-const isWin = process.platform === 'win32';
+const isWin = os.platform() === 'win32';
 
 const Builder = broccoli.Builder;
 const expect = chai.expect;