Re: Treating tests as special case

[Ricardo Wurmus <rekado@elephly.net>]

Hi Pjotr,

> And this hooks in with my main peeve about building from source. The
> building takes long enough. Testing takes incredibly long with many
> packages (especially language related) and are usually single core
> (unlike the build).

I share the sentiment.  Waiting for tests to complete can be quite
annoying.

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.

Packages with tests would then become leaf nodes in the graph — nothing
would depend on the packages with tests, only on the packages without
tests.  Building the test continuation would thus be optional and could
be something that’s done by the build farm but not by users who need to
compile a package for lack of substitutes.

The implementation details are tricky: can it be a proper continuation
from the time after the build phase but before the install phase?  Would
this involve reverting to a snapshot of the build container?  There are
packages that force “make check” before “make install” — do we patch
them or ignore them?  Will every package then produce one extra
derivation for tests?

--
Ricardo

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