The perfect Test and QA interview question

coffeemachine The perfect Test and QA interview question
If you’ve done quite a bit of hiring, you might have your favorite interview scheme, questions and dynamics which help you assess the skills of the testers in front you. I’ve done a lot of hiring the past 3 years for all position within my organization and I was thinking about the one question always coming back and which help me the most to get a feel about the person experience and pure test skills. I have a whole bunch of question around technical design for automation framework, pure technical questions (One of my favorite was a simple reverse of a linked list but I quickly realized that a lot of fresh graduates have never heard about linked list. I’m getting old icon smile The perfect Test and QA interview question ), I have simple technical question to get a feel on how fast they can work, evaluate a piece of work etc. But the one question I like the most is:

“You’re in charge to test our brand new coffee vending machine. Tell me how you would do it.”. I have variant with washing machine, vacuum cleaner etc icon smile The perfect Test and QA interview question

First of all, it tells you how the candidate think outside the box. It’s testing but nothing he has experienced or thought about in the past. I had candidates going completely blank because they could not adapt to something new and it’s never a good sign (you have to take into consideration stress coming from the interview. But still, it’s never a good sign when a candidate goes mute on a particular question, especially this one)

Testing of  a coffee machine covers all regular testing you would find in a software. It helps you understand in which area the candidate is the most comfortable and how he or she approaches testing:

  • Unit testing: I had candidate going really deep in the circuitry of the machine, testing each individual transistors. Most go to a higher level and test each individual functional component.
  • Functional testing: Some candidate approach functional testing through the actual mechanics of the machine (buttons, display etc.) while some other approach it from a software angle, leaving aside the mechanics. The best tester covers both.
  • White box/Black box: Again, your mileage may vary and you really see where your candidate is the most comfortable.
  • Performance/reliability testing: How fast can I get my coffee? How many coffee can I deliver in rush hours, MTBF etc. You can have a lot of fun in this area.
  • Usability: So much to do in the area but most candidate forget about it.
  • Localization testing: Again, most candidate don’t think about this one.
  • Security testing: Most candidate don’t go there but it’s always a good sign if they do. I had candidate forcing the door to get money, throwing water on it to see how far they can go until a power surge, sending 300v in the thing to understand how it would react etc.

Since I ask the candidate to use the white board, I can assess a bit their presentation skills, how they present informations etc. It’s definitely not a silver bullet to assess completely a candidate. But it’s definitely a good one to have in your toolbox !