Wycheproof testing harness example in Python # The following section will showcase how to write a simple testing harness to test a Python library implementing AES in GCM mode. We will use the cryptography package as an example of an AES-GCM implementation. For testing, we will use the pytest package, one of the most popular testing frameworks in Python. Prerequisites # Add the Wycheproof repository as a submodule to your existing repository.