Thursday, June 18, 2020

Billion Bubbles Challenge

Conor Fitzgerald tweeted the picture at the top the other day along with these words:

Testing some new hardware.. It has Turbo Bubble Technology

I smiled at the picture because it's sweet, but also because the idea of testing the bubble machine is fun. The "Billion Bubbles" label in particular put me in mind of those interview questions you hear about, how would you test a pen? and the like. 

So, how would you test whether Conor's new hardware could support the apparent claim of a billion bubbles?

I time-boxed myself at 10 minutes and put some thoughts down in a mind map:

Feel free to do the same and dump your thoughts into the comments.


  1. Hi James,

    that for the testing exercise!

    I think that we do not need to test a billion bubbles claim.

    Who are persons that matter in this context?
    2-5 year old children.
    Do they care if this claim is not true?
    Would they still persuade their parents to buy them this machine?
    Would parents check for this claim to be true?
    Would parents request their money back?

    My only test would be duration test, if that machine could produce bubbles for 10 minutes without failing.

    Regards, Karlo.

    1. Cheers Karlo. Thinking about who matters is a good line. I'm interested to know why you chose 10 minutes for your duration test.

    2. I choose 10 minutes based on following heuristic:

      "If a toy keeps child attention for period of 10 minutes, then it passed children playability test."

      This is based on my experience, when I observed children first contact with a new toy.

      With your follow up question, I realized that each hardcoded value should always be accompanied with explanation or heuristic.

      Regards, Karlo.