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Observation as a source of truth

18 Aug

Seeing something with your own eyes does not necessarily make it true.

In one of my previous testing roles, I was testing a software application which produced
image output files using custom hardware input devices. While I was working with a
developer at his computer, he opened an image file which exhibited characteristics I
hadn’t seen before when testing this product. I went to discuss the abnormality with our
image processing expert (let’s call him Jon), and he requested a copy of the file to help
determine whether this was the result of a software bug or a hardware fault.

I returned to the developer with this request, and watched as he copied the correct file to
a shared network drive. However, when I retraced my steps back to Jon’s desk and he
opened the image file, he saw only random ASCII characters. Jon said that this was not
a valid image file, and for a while I insisted that it was…

Eventually I returned to the developer’s desk seeking support, only to find out that he
could no longer open the original file on his computer either. Why? It turned out that his
computer had malfunctioned, and the file had become corrupted sometime between us
viewing it and him copying it to the network.

At this point I wondered why I had been questioning one of the country’s leading experts
on digital image processing, over something so basic as whether or not an image file
was valid. I’d been totally biased by the fact that I had observed the image with my own
eyes, rather than thinking logically about what piece of the puzzle I was missing in this
scenario.

First published here.

 
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Posted by on August 18, 2013 in Software Testing

 

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