Description
  This test validates that all of the BatteryManager attributes exist and are set to their correct values when battery is discharging.
Preconditions
  - 
    The device is unplugged from the charger before this test is run.
  
- 
    The battery must neither be empty or full, nor reach empty or full capacity during the test.
  
- 
    Waiting for battery level change to fire levelchange event, maybe need a long time