Process of making sure that older programming still works with the new changes is called Regression testing.
Any time you modify an implementation within a program, Regression software testing should be performed. This can be done by rerunning the existing test cases against the modified code to check whether the code change breaks the existing functionality. Regression testing is a normal part of the program development process and, in larger companies, is done by code testing specialists. Test department coders develop code test scenarios and exercises that will test new units of code after they have been written. One should try to spend as little time as possible doing regression testing without reducing the probability that you will detect new failures in old, already tested code.
Some strategies and factors to consider during this Regression Testing process include the following:
- Make changes (small and large) to data and find any resulting corruption.
- Identify tests that the program consistently passes and archive them.
- Watch for side effects of fixes. The bug itself might be fixed but the fix might create other bugs.
- Test fixed bugs promptly. The programmer might have handled the symptoms but not have gotten to the underlying cause.
- Focus on functional issues, not those related to design.
- Trace the effects of the changes on program memory.
- Write a regression test for each bug fixed.
- If two or more tests are similar, determine which is less effective and get rid of it.