Start unit tests

[drphilmarshall]

Now we have some class methods, we should write some unit tests for them.

[drphilmarshall]

Although, this only really makes sense once we have moved the PDF class into its own file - so let's leave this until we've done that.

[drphilmarshall]

PS. @aimalz you can crib from SLTimer, here.

[drphilmarshall]

Punting to the future - but this is important, we should not neglect it.

[aimalz]

In light of inconsistencies in the implementation of irregular data, I'm reviving this issue. I need to rigorously screen for those before an official code release!