Added: all missing functional tests

Beware, this PR adds a picture of a cute cat, along multiple functional tests.
So I have looked for a NPM module to that for me but I haven't found one. I'm all for doing things in Node JS since it's more portable but I find the code you suggest kinda hard to understand, whereas "dd" is pretty straightforward and documented everywhere on the internet. Do you want me to take the time to do the generation in Node or do you consider it's not a well-invested time?