There is a way to figure out the Activity life-cycle is properly used or not in your project.
In 4.X android version device you can see "Developer Settings" in Settings. In developer setting you have to enable the "Don't keep activities" which is destroyed all the activities in background as soon as possible.
In this case you app activity should not crashed, If its crashed your activity not follow the Android Activity life-cycle.
For your refernces here is the link : http://developer.android.com/training/basics/activity-lifecycle/index.html
I hope , this may help you little bit. :)