Idea: using quickcheck for strong tests at the token channel code

[realcr]

Quickcheck is a rust crate: https://github.com/BurntSushi/quickcheck
It allows to test various predicates by automatically generating input, possibly in a smart way.
I am not fully sure how it works internally, but it looks very promising.

We might be able to use quickcheck to test some critical parts like the token channel state machine for the Networker and the Funder. I have no idea if this will increase the amount of time the tests run, but we might be able to separate the quickcheck tests from the rest of the tests.

This is an idea for the future, I wanted to make sure that I don't forget.

[A4Vision]

Thumbs up. I think that TokenChannelCredit (the wallet itself) will also benefit from it.
A note for the future: the predicates might be non-trivial, because the tester must issue correct hash values.

[realcr]

Oh the hashes! I hope we can find a workaround there (: