Software reliability is the probability of the failure free operation of software in a given period of time under some certain conditions. Software testing can be defined as the process to detect the faults in totality and worth of developed computer software. Testing is very much important in assuring the quality of the software by identifying faults in software, and also most possibly removing them to make the software more efficient. But testing of the software for a long time may not ensure a bug free software and high reliability. Optimum amount of code also needs to be covered to make sure that the software is of good quality.