I'm not new to Python at all. I still have a copy of André Lessa's Python Developer's Handbook, which the receipt says I bought on 15th March 2001, and covers Python 1.6. Unfortunately in all the years since I've never used it much. My postgrad studies mostly used Verilog and my day job generally involves bash scripts and maintaining some really old PHP.
Still, it's a language I feel I want to use a lot, and I've attended the last two PyCon's in Ireland. At PyConIE 2013 I went to a tutorial on Test-Driven Development by Harry Percival, and at PyConIE 2014 I won a copy of his book Test-Driven Development in Python. I say won, but simply there were 40 books being given away (20 of these, and 20 of High Performance Python) and I was 40th in the queue. It feels like winning something, at least :)
Anyway, at the tutorial 2013 Harry made reference to the "Testing Goat", and I thought it was just a whimsical idea of his, but the goat was back in 2014 and it's on the cover of his book.
A bit of googling and it seems the Python Testing Goat is a thing.
As best as i can tell, the Testing Goat was a running joke at PyCon 2010 (see here) and it's become a mascot for Python Testing ever since. There was even a successful campaign to have O'Reilly put a goat on Harry's book instead of the expected snake.