Re: Treating tests as special case

[Ludovic Courtès]

Pjotr Prins <address@hidden> skribis:

> I am *not* suggesting we stop testing and stop writing tests. They are
> extremely important for integration (thought we could do with a lot
> less and more focussed integration tests - ref Hickey). What I am
> writing is that we don't have to rerun tests for everyone *once* they
> succeed *somewhere*. If you have a successful reproducible build and
> tests on a platform there is really no point in rerunning tests
> everywhere for the exact same setup. It is a nice property of our FP
> approach. Proof that it is not necessary is the fact that we
> distribute substitute binaries without running tests there. What I am
> proposing in essence is 'substitute tests'. 

Understood.

> If tests are so important to rerun: tell me why we are not running
> tests when substituting binaries?

Because you have a substitute if and only those tests already passed
somewhere.  This is exactly the property we’re interested in, right?

That is why I was suggesting putting effort in improving substitute
delivery rather than trying to come up with special mechanisms.

>> Ricardo Wurmus <address@hidden> skribis:
>> 
>> > An idea that came up on #guix several months ago was to separate the
>> > building of packages from testing.  Testing would be a continuation of
>> > the build, like grafts could be envisioned as a continuation of the
>> > build.
>> 
>> I agree it would be nice, but I think there’s a significant technical
>> issue: test suites usually expect to run from the build tree.
>
> What I understand is that Nix already does something like this. they
> have split testing out to allow for network access.

Do you have pointers to that?  All I’m aware of is the ‘doCheck’
variable that is unset (i.e., false) by default:

  
https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L1192

Ludo’.