gistfile1.html

<polymer-test name="my-widget-tests">
  <template>
    <my-widget object="{{ object }}"></my-widget>
  </template>
  <script>
    PolymerTest("my-widget-tests", {
      setup: function(data) {
        // Setup data binding for each test.
        data.object = {someValue: 2};
      },
      "should load data": function(widget) {
        assert.equal(widget.computedProperty, 2);
        assert.equal(widget.shadowRoot.firstChild.textContent, "My value is 2");
      }
      "should handle dynamic changes": function(widget, data, done) {
        data.object = {someValue: 5};
        endOfMicrotask(function() {
          assert.equal(widget.computedProperty, 5);
          assert.equal(widget.shadowRoot.firstChild.textContent, "My value is 5");
          done();
        });
      }
    })
  </script>
</polymer-test>