Experiments related to tuf-conformance testing

Rough design:

test runner is given a specific client wrapper as argument
The client wrapper is an executable that implements a client-under-test CLI (to be defined) -- each tested client will need a wrapper. That wrapper is responsible for doing the requested TUF client operations and also for making the client metadata cache available in the given location
test runner runs a single web server that individual tests can attach a simulated TUF repository to
each test sets up a simulated repository, attaches it to the server, runs the client-under-test against that repository. It can then modify the repository state and run the client-under-test again
the testrunner and web server run in the same thread: when a client-under-test process is started the web server request handler is manually pumped until the client-under-test finishes
the idea is that a test can run the client multiple times while modifying the repository state. After each client execution the test can verify
1. client success/failure
2. clients internal metadata state (what it considers currently valid metadata) and
3. that the requests client made were the expected ones
There should be helpers to make these verifications simple in the tests but these helpers are still largely unimplemented.

Install

Setting up the virtual environment (recommended):

pip install -e .

How to run the test rig against each client.

make test-python-tuf

make test-go-tuf