Handling Captchas with a LoadRunner script

A question that regularly comes up in the Mercury Support forum is how to get a LoadRunner script to handle websites that require you to type in the characters from a picture of a funny-looking piece of text before you can perform an action such as creating a new account. “Surely someone has come across this before, and has figured out how to correlate these values?”

Well…uh…no they haven’t. These are Captchas – they are used to prevent bots from doing nasty things like signing up for thousands of Hotmail accounts or leaving comment spam. If it was possible to write a LoadRunner script that could handle these automatically, then they wouldn’t be very effective.

Automated solutions used by spammers revolve around text recognition software and are ineffective. A spammer might be happy with a 0.01% success rate when signing up for webmail accounts, but it is hardly useful to a load tester who wants a 100% success rate. Boing Boing’s solution is also not very useful for load testing.

If you need to load test a website that uses captchas, then the only practical solution is for the developers to include the captcha value somewhere in the web page that is presented to the user. You can then correlate the value the same way you would normally. Just make sure that the code that does this is removed before the website goes live.