[skip changelog] Update client_example with proxy testing

[silvanocerza]

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• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
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• What kind of change does this PR introduce?

Adds some examples to the client_example project used to "test" gRPC comunication.

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[per1234]

The purpose of client_example is not testing. The purpose is documentation.

[rsora]

As we discussed internally, the original purpose of the client_example core was to provide code and a bit of documentation on how to use the CLI gRPC interface, but we would like to leverage it in the future as a component of our integration tests suite, this PR is a step in that direction.

[per1234]

I really don't understand why there is this trend of trying to use client_example for a purpose it was never intended for. This already happened once last year and it made it much less useful for the sake of documentation (#353). I don't see why we can't just write dedicated integration tests and leave the client example as an example.

I'd like to get input on this from the creator of the example: @cmaglie

[silvanocerza]

My main concern with the client_example is that it's practically never run but to verify that the gRPC has not been broken. Also it's not run automatically so it's often broken without anyone noticing.

Ideally well written tests can, and should, act as documentation for developers. I think right now the client_example fails on both since it's not run automatically and it doesn't cover all cases.

My goal is to remove it or adapt it in favour of integration testing, make it run automatically so we know if the gRPC interface has been broken, and also cover more cases.

[per1234]

Running client_example automatically is utterly trivial. It would be less work to add it to the workflow than it has been to talk about it.

[per1234]

I'm simply not convinced by the test as documentation argument. When writing tests, the sole goal should be to test. When writing documentation the sole goal should be to document. If you try to do both at the same time, you're going to end up needing to make compromises.

[cmaglie]

I'd like to get input on this from the creator of the example: @cmaglie

Heh, it started as a testing program to try out the grpc interface in the very early times but, once the gRPC API has been bootstrapped, to not waste it we transformed this test program into an example of how to use the grpc interface, something like a minimal client stub to tinker or to develop on.

I'm simply not convinced by the test as documentation argument. When writing tests, the sole goal should be to test. When writing documentation the sole goal should be to document. If you try to do both at the same time, you're going to end up needing to make compromises.

I agree, we have the integration test framework, we should add tests there.

Also, right now we have a single example_client that runs a bunch of random actions, IMHO it would make more sense to split it into smaller examples that show one feature at a time... but I don't know if it will ever happen, I guess this is a very low priority.