Route taken to complete:

1 - first test for the first rule dealing with an empty string 2 - test for a single job passed in 3 - test for a different single job passed in Up to this point I realise I have been putting implementation straight into the method rather than solving in the test first. 4 - fourth test written and passed. Test was first passed in test then extracted 5 - Fifth test written, this was an interesting one. It has balooned my functional code by quite a lot. Breaking down was useful though.