Modern C++ Programming with Test-Driven Development

9.11 Back to the GeoServer

Now that we’ve designed and implemented a ThreadPool, let’s take advantage of it. The first step is to change ​usersInBox​ to take a listener, or callback, as an argument. We update its code to return ​User​ objects to the client via the callback so that they can be asynchronously gathered.

The listener implementation in our test simply tracks users passed to its ​updated​ callback.

TEST(AGeoServer_UsersInBox, AnswersUsersInSpecifiedRange) {
   class GeoServerUserTrackingListener: public GeoServerListener {
   public:
      void updated(const User& user) { Users.push_back(user); }
      vector<User> Users;
   } trackingListener;

   server.updateLocation(
 bUser, Location{aUserLocation.go(Width ...