code: function bobSendsReplyMessage() {
      return Promise.all([
          sendMessage(bobTestClient.client),
          expectBobQueryKeys()
              .then(expectBobSendMessageRequest),
      ]).spread(function(_, ciphertext) {
          return ciphertext;
      });
  }
docs: Bob sends a message, first querying (but not claiming) e2e keys. Set the
  expectations and check the results.
  
  @return {promise} which resolves to the ciphertext for Ali's device.