If you're using an automated testing tool like winrunner and you are specifically performing regression testing then after the new test source is changed via a new build of software or web site then you won't change the winrunner script at all. This is because the nature of regression testing is to determine if the giving application has failed a test which it has successfully passed. So the test script must not be changed at all because it should be testing for the same thing every iteration. One last point is that in order to even use any automated software testing tool you have to have a stable application to test. If you don't have a stable application you'll be forced to change your test script with each build and that would be huge waste of time. So the process of regression testing using winrunner is the same as it would be for any testing tool, once the test script is created it should be re-run and not modified in order to prove that the bug that used to fail the test passes the script from then on.