Addons default to the root app's generateScopedName config

Author: dfreeman

README.md

@@ -440,6 +440,8 @@ new EmberApp(defaults, {
 });
 ```
 
+Note that addons may specify their own `generateScopedName` function, but otherwise they will fall back to using the one (if any) specified by the host application.
+
 ### Source Maps
 
 Ember CLI allows you to [specify source map settings](https://ember-cli.com/user-guide/#source-maps) for your entire build process, and ember-css-modules will honor that configuration. For instance, to enable source maps in all environments for both JS and CSS files, you could put the following in your `ember-cli-build.js`:

packages/ember-css-modules/index.js

@@ -115,7 +115,14 @@ module.exports = {
   },
 
   getScopedNameGenerator() {
-    return this.cssModulesOptions.generateScopedName || require('./lib/generate-scoped-name');
+    if (!this._scopedNameGenerator) {
+      let rootOptions = this._findRootApp().options.cssModules || {};
+      this._scopedNameGenerator = this.cssModulesOptions.generateScopedName
+        || rootOptions.generateScopedName
+        || require('./lib/generate-scoped-name');
+    }
+
+    return this._scopedNameGenerator;
   },
 
   getModuleRelativePath(fullPath) {