This can be difficult to determine. Many modern software applications are so complex,and run in such an interdependent environment, that complete testing can never be done. Common factors in deciding when to stop are:
What are Agile practices?
What are Agile Methods?
What are the Advantages of Agile Methodology?
What is Agile software development ?
Why Agile?
What is the difference between build and release?
What's the role of CMM Level in Testing?
What is the difference in writing the test cases for Integration testing and system testing?
What methodologies have you used to develop test cases?
What are the roles of glass-box and black-box testing tools?