This testing process to prove whether battery fixes will get the job done. Also for that testing FAA do limited test flights for two different aircraft. The prototype battery systems will be set on aircraft test. Battery changes itself covered redesigned internal battery components, improved insulation of the battery cells and create a new venting system.
However this is could be very good news for Boeing after very long and obstacle steps. As we know Boeing 787 Dreamliner was grounded since January 2012 after some battery issue and some fires on it. Comprehensive test of Boeing 787 Dreamliner will show us whether the proposed battery improvements will work as designed. The American authorities said in that the aircraft will not allow to return to service unless we are satisfied that new design ensures the safety of aircraft and its passengers.