is true while the last one is loading', function() {
          expect(echoAjax.loading).to.be.equal(true);

          respondToEchoRequest(server.requests[0]);
          return requests[0].completes.then(function() {
            // We're still loading because requests[2] is the most recently
            // made request.
            expect(echoAjax.loading).to.be.equal(true);

            respondToEchoRequest(server.requests[2]);
            return requests[2].completes;
          }).then(function() {
      