### Question:
LostClientManager implements ClientManager { @Override public void addLocationCallback(LostApiClient client, LocationRequest request, LocationCallback callback, Looper looper) { throwIfClientNotAdded(client); clients.get(client).locationCallbacks().add(callback); clients.get(client).looperMap().put(callback, looper); callbackToReports.put(callback, new LocationRequestReport(request)); } LostClientManager(Clock clock, HandlerFactory handlerFactory); static LostClientManager shared(); @Override void addClient(LostApiClient client); @Override void removeClient(LostApiClient client); @Override boolean containsClient(LostApiClient client); @Override int numberOfClients(); @Override void addListener(LostApiClient client, LocationRequest request,
      LocationListener listener); @Override void addPendingIntent(LostApiClient client, LocationRequest request,
      PendingIntent callbackIntent); @Override void addLocationCallback(LostApiClient client, LocationRequest request,
      LocationCallback callback, Looper looper); @Override boolean removeListener(LostApiClient client, LocationListener listener); @Override boolean removePendingIntent(LostApiClient client, PendingIntent callbackIntent); @Override boolean removeLocationCallback(LostApiClient client, LocationCallback callback); @Override void reportLocationChanged(final Location location); @Override void sendPendingIntent(final Context context,
      final Location location, final LocationAvailability availability,
      final LocationResult result); @Override void reportLocationResult(Location location,
      final LocationResult result); @Override void notifyLocationAvailability(final LocationAvailability availability); @Override boolean hasNoListeners(); @Override Map<LostApiClient, Set<LocationListener>> getLocationListeners(); @Override Map<LostApiClient, Set<PendingIntent>> getPendingIntents(); @Override Map<LostApiClient, Set<LocationCallback>> getLocationCallbacks();  }### Answer:
@Test(expected = IllegalArgumentException.class) public void addLocationCallback_shouldThrowExceptionIfClientWasNotAdded() throws Exception { manager.addLocationCallback(client, LocationRequest.create(), new TestLocationCallback(), mock(Looper.class)); }