Testing is my Profession

I admire the complexity which can emerge from elementary designs. Especially in the problem space. One example speaks for itself, the 'On/off app' : - an webapp consisting only from one button which can either turn 'things' on or off ( 'Picture 1 ' is an aproximate illustration of both visual states of the app) - 'things' are marketing campaigns, some more complex processes to send particular marketing messages under particular conditions to particular customers (details of such don't matter in this context) Picture 1 source: https://www.vecteezy.com/vector-art/88994-on-and-off-chrome-buttons Even when my team was highly qualified in software development, under the fog of communication  and implicit expectations that we missed, we discovered the following problems with the implementation:  Wrong template The template which we used in the test environment was not meant for production, the impact was low - only a few business