test: make the pacman hook-order test measure the source

The ordering asserts compared two string literals to each other ("05..." < "60..."), which is constant-true and never read the file. The invariant it claims to guard is boot-critical: pacman runs hooks in filename order, and a guard hook renamed past 60-mkinitcpio-remove would let a blocked transaction remove the current initramfs with this test still green.

The test now extracts the hook filenames the installer actually writes and compares those against the stock mkinitcpio hook name, so a rename flows into the assertion. Verified by mutation: renaming 05-zfs-snapshot to 70- in a source copy fails the new extraction compare where the old literal compare stayed true. Also added: every written hook must carry a two-digit ordering prefix.

1 files changed, 62 insertions, 10 deletions

diff --git a/tests/installer-steps/test_pacman_hook_order.py b/tests/installer-steps/test_pacman_hook_order.py
index 49acdbe..45058dd 100644
--- a/tests/installer-steps/test_pacman_hook_order.py
+++ b/tests/installer-steps/test_pacman_hook_order.py
@@ -1,26 +1,78 @@
-"""Regression tests for the pacman hook ordering safety invariant."""
+"""Regression tests for the pacman hook ordering safety invariant.
+
+pacman runs hooks in filename sort order, so the safety hooks archsetup
+installs (the pre-pacman ZFS snapshot and the live-update guard, both
+PreTransaction) must carry names that sort before mkinitcpio's stock
+60-mkinitcpio-remove.hook. Otherwise a blocked transaction can remove the
+current initramfs before the guard aborts, or after the snapshot window.
+
+The earlier version of this test asserted the ordering by comparing two string
+literals to each other, which is constant-true and never looked at the source.
+These tests extract the hook filenames the installer actually writes and
+compare those, so a rename in the source flows into the assertion.
+"""
 
 import os
+import re
 import unittest
 
 
 REPO_ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", ".."))
 ARCHSETUP = os.path.join(REPO_ROOT, "archsetup")
 
+MKINITCPIO_REMOVE = "60-mkinitcpio-remove.hook"  # stock mkinitcpio hook name
+
+WRITE_RE = re.compile(r">\s*/etc/pacman\.d/hooks/(\S+\.hook)\b")
+
+
+def written_hooks(text):
+    """Hook filenames the source writes (redirections into the hooks dir)."""
+    names = []
+    for line in text.splitlines():
+        if "rm -f" in line:
+            continue
+        m = WRITE_RE.search(line)
+        if m:
+            names.append(m.group(1))
+    return names
+
 
 class PacmanHookOrderTests(unittest.TestCase):
-    def test_safety_hooks_precede_mkinitcpio_removal(self):
+    @classmethod
+    def setUpClass(cls):
         with open(ARCHSETUP, encoding="utf-8") as source:
-            text = source.read()
+            cls.text = source.read()
+        cls.hooks = written_hooks(cls.text)
 
+    def hook_named(self, suffix):
+        matches = [h for h in self.hooks if h.endswith(suffix)]
+        self.assertEqual(
+            len(matches), 1,
+            f"expected exactly one written hook ending {suffix}, got {matches}")
+        return matches[0]
+
+    def test_safety_hooks_sort_before_mkinitcpio_removal(self):
+        # The invariant pacman actually enforces: filename sort order.
+        for suffix in ("zfs-snapshot.hook", "hypr-live-update-guard.hook"):
+            name = self.hook_named(suffix)
+            self.assertLess(
+                name, MKINITCPIO_REMOVE,
+                f"{name} must sort before {MKINITCPIO_REMOVE} or the guard "
+                "runs after the initramfs removal")
+
+    def test_every_written_hook_has_an_ordering_prefix(self):
+        # Ordering is deliberate; a hook without a numeric prefix sorts by
+        # accident of its first letter.
+        self.assertTrue(self.hooks, "extraction found no written hooks")
+        for name in self.hooks:
+            self.assertRegex(name, r"^\d{2}-",
+                             f"{name} lacks the two-digit ordering prefix")
+
+    def test_stale_unprefixed_hooks_are_cleaned_up(self):
+        # Migration from installs made before the numeric prefixes.
+        self.assertIn("rm -f /etc/pacman.d/hooks/zfs-snapshot.hook", self.text)
         self.assertIn(
-            "cat << 'EOF' > /etc/pacman.d/hooks/05-zfs-snapshot.hook", text)
-        self.assertIn(
-            "cat > /etc/pacman.d/hooks/10-hypr-live-update-guard.hook", text)
-        self.assertLess("05-zfs-snapshot.hook", "60-mkinitcpio-remove.hook")
-        self.assertLess("10-hypr-live-update-guard.hook", "60-mkinitcpio-remove.hook")
-        self.assertIn("rm -f /etc/pacman.d/hooks/zfs-snapshot.hook", text)
-        self.assertIn("rm -f /etc/pacman.d/hooks/hypr-live-update-guard.hook", text)
+            "rm -f /etc/pacman.d/hooks/hypr-live-update-guard.hook", self.text)
 
 
 if __name__ == "__main__":