Ruby on Rails

 This is something I realized is that if you try to write more bullet proof code, it may have alot of extra checks in it. That may make it harder to test because there are more conditions. In theory your code is trying to cover cases that may or may not occur but it is trying to be more robust ... However, then when you run something like the simplecov gem - https://github.com/colszowka/simplecov If your code has various checks in it that are not tested because they are not typical, your code module will get a bad percentage mark for not being fully tested.