how to do regression testing code example

Example 1: what is regression testing

Regression testing is testing existing 
software applications to make sure that
a change or addition hasn’t broken any 
existing functionality. Its purpose is 
to catch bugs that may have been accidentally
introduced into a new build or release candidate, 
and to ensure that previously eradicated 
bugs continue to stay dead.

Example 2: which regression testing should be automated

Tests which are stable
• Repeated frequently
• Simple and require no tester input are good
candidates for automation