It is not possible to perform 100% testing of any software or product. However, can do the following steps to come closer :
Setting a hard limit on :
* Percentage of test cases passed
* Number of bugs discovered
Setting a red flag in case :
* There is a depletion of test budged
* There is a breach of deadlines
Setting a green flag in case :
* The entire functionality is covered in test cases
* All critical and major bugs must have a ‘CLOSED’ status
