[TNL-4029] Show error if server returns customised error message

lms/static/js/spec/edxnotes/plugins/store_error_handler_spec.js

@@ -0,0 +1,36 @@
+define([
+  'jquery', 'underscore', 'annotator_1.2.9',
+  'common/js/spec_helpers/ajax_helpers',
+  'js/spec/edxnotes/helpers',
+  'js/edxnotes/views/notes_factory'
+], function ($, _, Annotator, AjaxHelpers, Helpers, NotesFactory) {
+  'use strict';
+  describe('Store Error Handler Custom Message', function () {
+    beforeEach(function () {
+      spyOn(Annotator, 'showNotification');
+      loadFixtures('js/fixtures/edxnotes/edxnotes_wrapper.html');
+      this.wrapper = document.getElementById('edx-notes-wrapper-123');
+    });
+
+    afterEach(function () {
+      _.invoke(Annotator._instances, 'destroy');
+    });
+
+    it('can handle custom error if sent from server', function () {
+      var requests = AjaxHelpers.requests(this);
+      var token = Helpers.makeToken();
+      NotesFactory.factory(this.wrapper, {
+        endpoint: '/test_endpoint',
+        user: 'a user',
+        usageId: 'an usage',
+        courseId: 'a course',
+        token: token,
+        tokenUrl: '/test_token_url'
+      });
+
+      var errorMsg = 'can\'t create more notes';
+      AjaxHelpers.respondWithError(requests, 400, {error_msg: errorMsg});
+      expect(Annotator.showNotification).toHaveBeenCalledWith(errorMsg, Annotator.Notification.ERROR);
+    });
+  });
+});