I have returned to this book now that the book is out of beta.
I also started using a different repo: https://github.com/chriseyre2000/property_testing
The only difference between my code and the samples is that I am using the pipe syntax where possible. My Execism.IO background in Elixir is also forcing me to make style changes to keep the code in Elixir format.
Part 1 chapter 4 does use the erlang queue library. It would be good to be able to get Elixir documentation on erlang packages.
The part 2 sample code is broken but I am working on fixing in my repo.
It turned out to be easier to download the code from the pragprog site.