nixos/restic: test that initialize = false works correctly

This is a test that was proposed in #264849, which was not merged in favour of #264882.

Based-on-patch-by: "Patrick Steinhardt" <[email protected]>

nixos/tests/restic.nix

@@ -120,8 +120,15 @@ import ./make-test-python.nix (
           "cp -rT ${testDir} /opt",
           "touch /opt/excluded_file_1 /opt/excluded_file_2",
           "mkdir -p /root/restic-rclone-backup",
-          "restic-remote-noinit-backup init",
+      )
+
+      server.fail(
+          # test that noinit backup in fact does not initialize the repository
+          # and thus fails without a pre-initialized repository
+          "systemctl start restic-backups-remote-noinit-backup.service",
+      )
 
+      server.succeed(
           # test that remotebackup runs custom commands and produces a snapshot
           "timedatectl set-time '2016-12-13 13:45'",
           "systemctl start restic-backups-remotebackup.service",
@@ -137,7 +144,8 @@ import ./make-test-python.nix (
           "systemctl start restic-backups-remote-from-file-backup.service",
           'restic-remote-from-file-backup snapshots --json | ${pkgs.jq}/bin/jq "length | . == 1"',
 
-          # test that remote-noinit-backup produces a snapshot
+          # test that remote-noinit-backup produces a snapshot once initialized
+          "restic-remote-noinit-backup init",
           "systemctl start restic-backups-remote-noinit-backup.service",
           'restic-remote-noinit-backup snapshots --json | ${pkgs.jq}/bin/jq "length | . == 1"',