The Pursuit of the Unreplicable Bug


ghostbusters.gifI’ve been recently testing a web-based application that produced a very interesting defect. It seemed that in one particular screen, a user (with the right combination key strokes and mouse clicks) could actually enter a supposedly uneditable error message field and enter text! At first i wasn’t able to repeat this behaviour but with the words from a James Bach article ringing in my ears about “…ignoring unreproducible bugs at your peril”, i logged it waiting for the right opportunity to attack it.

I had already spent time looking for this ‘bug’ but figured that i would put it to one side and come back to it with fresh eyes and clearer thoughts. Interestingly enough, the developers caught hold of this bug and attempt to replicate in their dev environments – i was even ‘challenged’ in a joking way that if i couldn’t reproduce the bug within 5 attempts then it didn’t exisit!! Oh, did the competitive urges come out then! (This was done in good spirits – we have a tremendous rapport between developers, testers and BA’s). However, it was another developer that found the key/mouse strokes that generated the bug and we discovered that it was a validation error on that web page!

So what were the lessons learnt?

  1. Exploratory testing found this bug – some may say that discovery was a ‘fluke’ but scripted testing would never have picked this bug up.
  2. Fresh eyes and a clearer head can aid tremendously in trying to replicate a bug (especially one discovered late in the day!)
  3. Having a rapport with developers helps in solving bugs – personal agendas and politics are put to one side for the greater good of the ‘team’
  4. Working alongside developers generally breaks down communication barriers (percieved and physical)
  5. Unreproducable bugs ARE best ignored at ones own peril – in this case finding this bug lead to a tightening of field validation for the application
  6. Bugs are bugs are bugs…testers find them, developers fix them, buisness decide what they want done with them – never give up on trying to replicate bugs that are difficult to reproduce!
  7. Teamwork – i honestly believe the power of many can be greater than the power of one
  8. It’s tremendously satisfying finding a bug that is difficult to find and reproduce – the testing equilivant of a three-pointer!
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Author: bjosman

Principal Consultant at OsmanIT brian.osman@osmanit.com

2 thoughts on “The Pursuit of the Unreplicable Bug”

  1. Hi Brian – good to see you sharing your excellent software testing knowledge in the blogosphere. Keep pursuing those unreplicable bugs. Best wishes.

    Brendon

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