regression test is 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: how many test case in your regression

It depends on the project.
In my current project out of 1200 test cases 
in regression suite around %70 is automation.
We use 6 vm to perform parallelexecution it takes
3 hours to execute depends on the test data.