When writing a test that needs to speak to an appengine endpoint, it's difficult to make the test wait for a response from a server. I've tried a bunch of permutations on waiting for "ready" on various elements, and triggering stuff. but I keep having to go back to writing a custom event and triggering it as below. Is there an easier way to wait…

api-test-needs-custom-event.html

<test-fixture id="basic">
  <template>
    <r-api path="api.widget.list"></r-api>
  </template>
</test-fixture>

<dom-module id="fake-google-api">
  <template>
    <iron-ajax id="widgetList"
               auto
               url="testdata/widget.list.json"
               handle-as="json"
               on-response="handleResponse"></iron-ajax>
    </template>
</dom-module>
<script>
  Polymer({
    is: 'fake-google-api',
    properties: {
      widgetListData: {
        type: Object,
        value: {}
      }
    },
    handleResponse: function(request) {
      if(this.id === 'widgetapi') {
        this.set('widgetListData', request.detail.response);
        this.fire('google-api-load');
      }
    },
    listeners: {
      'test': 'executeTests'  // I shouldn't need to create this listener.
    },
  });
  suite('r-api tests', function() {
    var element;

    setup(function() {
      replace('google-client-loader').with('fake-google-api');
      element = fixture('basic');
    });

    test('Gets a simple widget.list endpoint response', function(done) {
      element.$.widgetapi.executeTests = function() {  // I shouldn't have to write this custom event.
        flush( function() {
        assert.deepEqual(element.result, {widgets: ['1', '2']});
          done();
        });
      }.bind(this);
    });
  });
</script>