Selenium is a testing framework for web applications. I wanted to write specific tests for joomlacomment since a long time, but I've never managed to find time for this.
Now I'm reading selenium documentation and I'm trying to make some tests to automate the process of adding new features and testing if they at all work :) If you wish to help, you are welcome to make some tests and I will add them to the future test suite.
How to write a test? Well it is super easy: just spend few minutes reading the documentation:
http://seleniumhq.org/docs/01_introducing_selenium.html
What is this good for? Well if we have more tests that we can run, we can save time, we can be sure that new releases have fewer bugs - you as an end user will benefit most of it.