We ask all candidates to complete a short coding exercise to solve a particular problem. The specification is left vague to allow the candidate to show their initiative in not just writing a solution but also demonstrate how they write tests, include documentation and package the project to run e.g. using a virtualenv. On this occasion, the supplied code had almost zero documentation and contained incomplete packaging to allow us to run the code (requirements.txt was incomplete). We used a virtualenv which installed the requirements.txt but virtualenv 3.4 creates a python2.7 environment. The code was also not tested against multiple Python versions because "I didn't think anyone would actually run it so didn't think it was necessary to do this". We offered the candidate a second opportunity and whilst the code was changed, the tests and documentation were not. There were also no instructions for using the server once it was running and we had to read the source to figure out how to use it. As a result, we decided not to proceed with the application due to lack of care shown in an interview situation, which we felt reflected poorly on how the candidate would work in the future.