nixos/test-driver: highlight driver log lines

There is a whole lot of noise in a NixOS test log due to journal,
commands, and test driver messages all being mixing together.
With this commit the test driver messages are highlighted so you don't
have to squint too much to see where a subtest starts and ends or what
was the last command being run.

Here's an excerpt from a highlighted log:

    machine # [    6.647826] dhcpcd[668]: eth0: adding default route via 10.0.2.2
    machine # I've had a great day!
    (finished: must succeed: curl -sfL https://example.com/how-are-you? | tee /dev/stderr, in 0.19 seconds)
    (finished: subtest: Privoxy can filter https requests, in 0.22 seconds)
    subtest: Blocks are working
    machine: waiting for TCP port 443
    machine # Connection to localhost (::1) 443 port [tcp/https] succeeded!
    (finished: waiting for TCP port 443, in 0.03 seconds)
    machine: must fail: curl -f https://example.com/ads 1>&2
    machine # [    6.730608] nscd[742]: 742 monitored file `/etc/resolv.conf` was written to
    machine # [    6.733071] privoxy[814]: 2022-04-14 09:41:01.695 7fa995c39640 Actions: +block{Fake ads} ...
    machine # curl: (22) The requested URL returned error: 403
    machine # [    6.753098] systemd[1]: Stopping Name Service Cache Daemon...
    machine # [    6.755632] systemd[1]: nscd.service: Deactivated successfully.
    machine # [    6.757069] systemd[1]: Stopped Name Service Cache Daemon.
    (finished: must fail: curl -f https://example.com/ads 1>&2, in 0.07 seconds)
    machine: must succeed: curl -f https://example.com/PRIVOXY-FORCE/ads 1>&2
    machine # [    6.765099] systemd[1]: Starting Name Service Cache Daemon...
    machine # [    6.781519] nscd[925]: 925 monitoring file `/etc/passwd` (1)
    machine # [    6.844105] systemd[1]: Reached target Network is Online.
    machine # [    6.848860] privoxy[814]: 2022-04-14 09:41:01.805 7fa995c39640 Actions: +block{Fake ads} ...
    machine # [    6.856068] nscd[925]: 925 monitoring file `/etc/nsswitch.conf` (8)
    machine # [    6.858229] systemd[1]: Reached target Multi-User System.
    machine # [    6.858934] nscd[925]: 925 monitoring directory `/etc` (2)
    machine # [    6.861315] systemd[1]: Startup finished in 2.374s (kernel) + 4.451s (userspace) = 6.826s.
    machine # Hot Nixpkgs PRs in your area. Click here!
    machine # [    6.873055] nscd[925]: 925 monitoring directory `/etc` (2)
    machine # [    6.874489] nscd[925]: 925 monitoring file `/etc/nsswitch.conf` (8)
    machine # [    6.875599] nscd[925]: 925 monitoring directory `/etc` (2)
    (finished: must succeed: curl -f https://example.com/PRIVOXY-FORCE/ads 1>&2, in 0.12 seconds)
    (finished: subtest: Blocks are working, in 0.22 seconds)
    subtest: Temporary certificates are cleaned
    machine: must succeed: test $(ls /run/privoxy/certs | wc -l) -gt 0
    (finished: must succeed: test $(ls /run/privoxy/certs | wc -l) -gt 0, in 0.02 seconds)
    machine: must succeed: date -s "$(date --date '12 days')"
    (finished: must succeed: date -s "$(date --date '12 days')", in 0.02 seconds)
    machine # [    6.959589] systemd[1]: Started Logrotate Service.
    machine # [    6.966685] systemd[1]: Starting Cleanup of Temporary Directories...
    machine # [    6.974783] systemd[1]: logrotate.service: Deactivated successfully.
    machine # [    7.004493] systemd[1]: systemd-tmpfiles-clean.service: Deactivated successfully.
    machine # [    7.005457] systemd[1]: Finished Cleanup of Temporary Directories.
    machine: must succeed: test $(ls /run/privoxy/certs | wc -l) -eq 0
    (finished: must succeed: test $(ls /run/privoxy/certs | wc -l) -eq 0, in 0.01 seconds)
    (finished: subtest: Temporary certificates are cleaned, in 0.15 seconds)
    (finished: run the VM test script, in 7.44 seconds)
    test script finished in 7.48s
    cleanup
    kill machine (pid 8)

0 files changed, 0 insertions, 0 deletions