Hey @yonran. Sorry this has sat around so long.

I would largely base the tests on the tests for the RSA versions of the classes you're adding. You can find these in jwk_test.py and util_test.py.

As for how to run tests, you can install josepy and it's dependencies in a virtual environment by running commands like the following from the root of the repo:

virtualenv venv
source venv/bin/activate
pip install -e .[dev,tests]

After that, you can run tests with tox by running:

tox -e py27

You can replace 27 whichever Python version you want to test against as long as that version of Python is installed on your system.

I would love to see this and #45 implemented, as ES256 is a MUST requirement for ACME.

Quoting RFC 8555 Section 6.2 here:

An ACME server MUST implement the "ES256" signature algorithm
[RFC7518] and SHOULD implement the "EdDSA" signature algorithm using
the "Ed25519" variant (indicated by "crv") [RFC8037].

Indeed it is a MUST for an ACME server.

While the small Certbot team would also love to see this implemented, we probably won't be able to get to it for a little while. If you'd like to see it sooner, we'd accept well written PRs for these features.