Re: Caching test results separately?

["Ludovic Courtès" <ludo@gnu.org>]

Hello,

Josselin Poiret <dev@jpoiret.xyz> skribis:

> As it stands it's really not possible, as
>
> 1) testing is part of the build process itself and
> 2) we can't look-up any stateful info like this from the building
> process (of course!)
>
> But I would really like for tests to move out of build phases, the
> advantages would be twofold: less build time for a lot of packages, and
> better environment management for tests (we could rely on better
> interaction with other packages, more complicated mocking, use linux
> namespaces to their fullest extent, etc.).  That would require a huge
> change to Guix though, so it's more of a dream than anything concrete.

I don’t think that’s really possible in practice.

But… there’s another idea I’ve been willing to work on for some time:
recognizing build results that are identical modulo references, such
that we can replace full rebuilds by mere reference rewriting in some
cases.

Examples of derivations that lead the same result modulo references:
building a package with/without tests, building a package with various
test suite adjustments, building a package with different versions of
Bash or whatever interpreter is used by its build scripts, etc.

I’m kinda stuck by the fact I don’t want to add more C++ code though,
which means we first need to get that daemon in Scheme…

Ludo’.