System tests

[Ludovic Courtès]

Hello Guix!

I just pushed a couple of new modules to run system tests.  As done in
NixOS¹ (in Perl + Bash), the idea is to run the system under test in a
VM and to instrument the guest system with a backdoor so we can fiddle
with it from the outside.

Here, the backdoor is obviously a Guile REPL, which is pretty cool.  :-)

Currently there’s only one test series, in (gnu tests base).  You’re
welcome to look at it and comment!  The ‘marionette’ procedures used in
there are what allows us to execute code in the system under test.

In the system under test, we can of course call any system call that
Guile provides, we can use (gnu system herd) to query the Shepherd, etc.
The ‘marionette-type’ procedure allows us to simulate typing at the
keyboard, although that’s a bit harder to use due to lack of
synchronization.

Anyway, to run the test:

  make check-system

Feedback welcome!

Ludo’.

¹ https://github.com/NixOS/nixpkgs/blob/master/nixos/lib/test-driver/Machine.pm