Clear features cache only when logged in user changes

Clear the features cache only when the logged-in user changes,
rather than on any change to session data.

h/static/scripts/features.js

@@ -33,10 +33,7 @@ function features ($document, $http, $log, $rootScope) {
   var featuresUrl = new URL('/app/features', $document.prop('baseURI')).href;
   var fetchOperation;
 
-  // FIXME - This should be changed to clear the feature flag cache
-  // only in response to the USER_CHANGED event once
-  // https://github.com/hypothesis/h/pull/2674 lands
-  $rootScope.$on(events.SESSION_CHANGED, function () {
+  $rootScope.$on(events.USER_CHANGED, function () {
     cache = null;
   });
 

h/static/scripts/test/features-test.js

-"use strict";
+'use strict';
 
 var mock = angular.mock;
 
+var events = require('../events');
+
 describe('h:features', function () {
   var $httpBackend;
+  var $rootScope;
   var features;
   var sandbox;
 
@@ -26,6 +29,7 @@ describe('h:features', function () {
 
   beforeEach(mock.inject(function ($injector) {
     $httpBackend = $injector.get('$httpBackend');
+    $rootScope = $injector.get('$rootScope');
     features = $injector.get('features');
   }));
 
@@ -122,5 +126,20 @@ describe('h:features', function () {
       features.flagEnabled('foo');
       $httpBackend.flush();
     });
+
+    it('should clear the features data when the user changes', function () {
+      // fetch features and check that the flag is set
+      defaultHandler();
+      features.fetch();
+      $httpBackend.flush();
+      assert.isTrue(features.flagEnabled('foo'));
+
+      // simulate a change of logged-in user which should clear
+      // the features cache
+      $rootScope.$broadcast(events.USER_CHANGED, {});
+      defaultHandler();
+      assert.isFalse(features.flagEnabled('foo'));
+      $httpBackend.flush();
+    });
   });
 });