Use Parsec Mock for testing

[hug-dev]

This commit changes the CI script to start Parsec Mock there. Moves the
ping test from the already existing mock interface to Parsec Mock.

In the future the tests in src/core/testing can be added in the Parsec Mock repo and used from the mock_service.rs test file. That way the test cases can benefit all clients.

[ionut-arm]

I've investigated a bit, it seems the failures are pretty much random, couldn't rat out the exact cause. Most of my testing so far has been around whether the socket exists, as the client seems to get a connection error and I was expecting it to be due to a delay in the mock service. But even when I made sure to wait until the socket exists (and then some more), failures still occured. I can't tell what exactly is happening, as locally I've not been able to reproduce the error. My only idea for now is to just move the testing into a container and hope that solves it.

[ionut-arm]

Ok, the problem here seems to be in the mock service - because of the way recv works in Python on Unix Domain Sockets, it simply returns as soon as it gets something from the connection. If the client isn't fast enough, the service reads the first few bytes of the request and tries to work with that as a full request, which it isn't, so it closes the connection.

The fix, therefore, needs to make sure the mock service keeps polling the connection until it gets no bytes and hits a timeout. Will update this PR once I get that merged.

[hug-dev]

Wow, nice find!

I am wondering why the logs of the service do not show the following line though?

print("Received unexpected request {}".format(b64_received_data))

[ionut-arm]

I am wondering why the logs of the service do not show the following line though?

print("Received unexpected request {}".format(b64_received_data))

It's because when it runs in a non-interactive shell the flushes seem to occur much less frequently.

[hug-dev]

Can't approve my own PR but this looks good 👌 Thanks for debugging this out.

[anta5010]

I would got for 1sec, but it's not important