ajax.url = null;
            ajax.handleAs = 'text';

            Polymer.Base.async(function() {
              resolve();
            }, 1);
          });
        });

        test('deduplicates multiple changes to a single request', function() {
          return new Promise(function(resolve, reject) {
            ajax.addEventListener('request', function() {
              server.respond();
            });

            ajax.addEventListener('response', function() {
              try {
                expec