Ed25519 is a high speed public key signature system. ed25519.py is the reference implementation that has been optimized for a faster runtime. It does not include protections against side channel attacks. The original reference implementation can be found on the authors website.
This code is almost never what you want. It is hopefully useful in cases where you absolutely cannot have any C code dependencies. Unless you absolutely cannot have C code dependencies you would be better off using something like PyNaCl.
ed25519.py uses tox to run the test suite. You can run all the tests by using:
$ tox- IRC (#cryptography-dev - irc.freenode.net)