improve version and mirror updating

tests/utils.bats

@@ -258,3 +258,50 @@ pacman_log() {
   run initramfs_build_failed
   [ "$status" -eq 0 ]
 }
+
+# --- mirrors ----------------------------------------------------------------
+
+setup_mirrors() {
+  export MIRRORLIST="$BATS_TEST_TMPDIR/mirrorlist"
+  cat > "$MIRRORLIST" << 'LIST'
+## Worldwide
+#Server = https://commented.example/archlinux/$repo/os/$arch
+Server = https://first.example/archlinux/$repo/os/$arch
+Server = https://second.example/$repo/os/$arch
+LIST
+  # lastsync is $SYNCED, a Unix time
+  stub curl 'echo "$SYNCED"; [ -n "$SYNCED" ]'
+  source "$REPO/utils.sh"
+}
+
+@test "first_mirror is the first Server line that isn't commented out" {
+  setup_mirrors
+  [ "$(first_mirror)" = "https://first.example/archlinux" ]
+}
+
+@test "mirror_age_hours reads the first mirror's lastsync" {
+  setup_mirrors
+  export SYNCED="$(( $(date +%s) - 30 * 3600 ))"
+  run mirror_age_hours
+  [ "$status" -eq 0 ]
+  [ "$output" = 30 ]
+  called curl -sf --max-time 10 https://first.example/archlinux/lastsync
+}
+
+@test "mirror_age_hours fails when the mirror can't be reached or has no lastsync" {
+  setup_mirrors
+  export SYNCED=""
+  run mirror_age_hours
+  [ "$status" -ne 0 ]
+  export SYNCED="<html>Not Found</html>"
+  run mirror_age_hours
+  [ "$status" -ne 0 ]
+}
+
+@test "mirror_age_hours fails without a mirrorlist" {
+  setup_mirrors
+  rm "$MIRRORLIST"
+  run mirror_age_hours
+  [ "$status" -ne 0 ]
+  not_called curl
+}