Ideas for stress testing GPS via GadgetBridge

I have tested a bit again with current stable firmware and GB (2v17 and 0.74) and the changes for android from https://github.com/espruino/BangleApps/p­ull/2534 since without them I can not get GBGPS to activate on GadgetBridge:

• Connect watch to GB and start GPS Info to get GPS updates -> works fine
  
  • Battery level available in GB
    
  • Connected shown in GB
    
  • Sending notification works
    
  • characteristic write messages in logcat
    
• Put watch into metal box
  
  • Battery level vanished from GB
    
  • Few ms of disconnected (grey) state, then connected state shown again
    
  • After "reconnect" still no battery level
    
  • GB still trying to send GPS, but not characteristic write messages
    
  • Debug notification does not work, just added to queue like GPS messages
    
• Take watch out of box
  
  • nothing changes, stays fake connected without battery level
    
• Reload watch (2 sec button press)
  
  • nothing changes again
    
• Disconnect and reconnect watch with GB menu
  
  • Everything returns to normal
    
    

It seems there is a problem in the GadgetBridge GPS handling code, not the GPS code on the watch. It is in the metal box when the problem starts, so no influence on GB at that point in time. Without triggering GBGPS on the watch the "fake" reconnect does not happen and the actual reconnect after the box is openend restores full functionality.
Somehow some state in GB seems to be not cleared as it should be when the GPS service is active.