Add tup2 to tup9 for Gen

[vch9]

Alternative (and easy) solution for #108.

Nothing smart happening there.

[jmid]

I think these are fine. What do you think @c-cube?

Even if they are so straightforward, it would be nice to include tests of them.
Doing so, will require Printers - which should be included for the generators to be generally useful.

For uniformity it would be nice to add t2-t9 to QCheck as well with both generators and printers - and ideally also shrinkers...

[c-cube]

can we get the same in QCheck.Gen?

[vch9]

Yes I will add these in QCheck.

When I did this PR I thought QCheck2 would replace QCheck. However, I started the migration in our project where we have a lot of QCheck tests and the execution's time has raised a lot. I now believe QCheck is still relevant in many cases.

[c-cube]

Indeed, it might be that they both have their use :-).

[vch9]

It is ready again for a review @c-cube and @jmid. I added printers, shrinkers, generators and arbitraries? for QCheck and printer for QCheck2. I also added a lot of tests aswell. It's a lot of boiler-plate code thought.

[c-cube]

Looks good I think. Thanks for the patience on such boilerplat-y code :D

[jmid]

However, I started the migration in our project where we have a lot of QCheck tests and the execution's time has raised a lot.

It would be great if you could extract a representable test case and share it here 🙏‍🙂

QCheck2 is a great effort! In the long run, I still hope for it to replace QCheck.
It will require some more engineering, testing, and fine-tuning evidently.
A real-world example test that takes too long w/QCheck2 would be a good starting point though (in comparison, the shrinker benchmarking in #177 is mostly based on artificial tests).

[vch9]

A real-world example test that takes too long w/QCheck2 would be a good starting point though (in comparison, the shrinker benchmarking in #177 is mostly based on artificial tests).

It's a test in the Tezos code base, there is a lot of dependencies going on there. I don't know if it can be easily extracted for our testing purpose.