What Fax Machines can teach us about Performance Testing
A long time ago, a friend was giving me a quick tour of his small business. At the time, the internet wasn’t yet what we know it as today, so fax was still a very popular medium of B2B communication. His company sent out millions of faxes every week for things like mortgage rates, product information, travel reservations and many other things we now take for granted as a push notification or email. But at the time, fax was cool.
As we were walking around his offices and just talking about the business, he showed me their testing area, where they would send test faxes much like digital marketers will send out test email newsletters today. What was weird about this testing area was the fax machines. This company sent out faxes for a living. This guy – a former Bell Labs guy – knew everything there was to know about the transaction of a fax. But the fax machines they used for testing were ancient! The fax machines were old, faded beige plastic and used that hideous curly thermal paper.
He saw the look on my face, and he knew what I was thinking, but he remained silent, allowing me to form the question in my head. He had done this before. “Why do you test on these old piece-of-crap fax machines?!?” He had set me up on purpose, and he answered the question with three words that I’ll never forget. Three words that have shaped my perspective on testing just about anything: “Least common denominator.”
Huh? I didn’t get it yet. So he continued, “if the fax looks good on this piece of crap, it’ll look fantastic when it comes off any relatively new fax machine.” There was that “Ah ha!” moment, and I got it.
Jump ahead just a few years, and we’re at that same place when it comes to testing web apps and web pages. You don’t go out and buy the very latest, fastest, baddest, most awesome machines to test on. No, you get the oldest, slowest viable piece of junk on which your app or web site is supposed to function, and test everything on those devices. When we say “function” here, we mean its performance. Its speed.
If your web app runs fast on an iPhone 4, chances are it’ll be very slick on an iPhone 6 Plus. Test on the least common denominator to make sure your web apps work really well on the very latest devices.