code: function expectBobQueryKeys() {
      // can't query keys before ali has uploaded them
      expect(aliTestClient.deviceKeys).toBeTruthy();
  
      const aliKeys = {};
      aliKeys[aliDeviceId] = aliTestClient.deviceKeys;
      console.log("query result will be", aliKeys);
  
      bobTestClient.httpBackend.when(
          "POST", "/keys/query",
      ).respond(200, function(path, content) {
          expect(content.device_keys[aliUserId]).toEqual(
              {},
              "Expected Bob to key query for " + aliUserId + ", got " +
              Object.keys(content.device_keys),
          );
          const result = {};
          result[aliUserId] = aliKeys;
          return {device_keys: result};
      });
      return bobTestClient.httpBackend.flush("/keys/query", 1);
  }
docs: Set an expectation that bob will query alis keys; then flush the http request.
  
  @return {promise} which resolves once the http request has completed.