test(maint): add VM and nspawn remedy scenario harness

Nine break/fix/assert scenarios run the real maint fix inside the test VM. The runner batches non-conflicting scenarios into one VM boot, restores the snapshot only between groups, and leaves the base image pristine afterwards. A systemd-nspawn fast lane runs the pacman-level group against a cached pacstrap rootfs in seconds. The plan layer validates the scenario contract without a VM and carries a 19-test unit suite. make test-maint wires the VM lane in.

The zfs lane is filtered but unexercised: the FS_PROFILE=zfs base image fails to build (ZFS DKMS module not found on linux-lts 6.18). The failure is tracked in the todo.

1 files changed, 20 insertions, 0 deletions

diff --git a/scripts/testing/maint-scenarios/21-cache-uninstalled.sh b/scripts/testing/maint-scenarios/21-cache-uninstalled.sh
new file mode 100644
index 0000000..ea788e8
--- /dev/null
+++ b/scripts/testing/maint-scenarios/21-cache-uninstalled.sh
@@ -0,0 +1,20 @@
+# shellcheck shell=bash disable=SC2034  # sourced by run-maint-scenarios.sh
+# Scenario: paccache -ruk0 drops every cached version of uninstalled packages.
+#
+# Fake versions of a package that is NOT installed disappear entirely, while
+# an installed package's cached version survives the uninstalled-only pass.
+SCENARIO_DESC="cached versions of uninstalled packages dropped"
+SCENARIO_GROUP="packages"
+SCENARIO_PROFILES="any"
+
+scenario_break() {
+    mexec "touch /var/cache/pacman/pkg/maintghostpkg-2.1-1-x86_64.pkg.tar.zst /var/cache/pacman/pkg/maintghostpkg-2.2-1-x86_64.pkg.tar.zst /var/cache/pacman/pkg/bash-9.9-1-x86_64.pkg.tar.zst"
+}
+
+scenario_fix() {
+    mfix cache_clean_uninstalled
+}
+
+scenario_assert() {
+    mexec "test ! -e /var/cache/pacman/pkg/maintghostpkg-2.1-1-x86_64.pkg.tar.zst && test ! -e /var/cache/pacman/pkg/maintghostpkg-2.2-1-x86_64.pkg.tar.zst && test -e /var/cache/pacman/pkg/bash-9.9-1-x86_64.pkg.tar.zst"
+}