fix: keep online update recovery available

scripts/test-update-fixture.sh

@@ -92,6 +92,7 @@ SH
   cat > "$mock_bin/systemctl" <<'SH'
 #!/bin/sh
 printf '%s\n' "$*" >> "$MOCK_SYSTEMCTL_LOG"
+[ "${MOCK_UPDATE_PATH_START:-success}:$*" != 'fail:start kaidi-update.path' ] || exit 1
 exit 0
 SH
 
@@ -170,6 +171,7 @@ SH
 build_release() {
   local fixture=$1
   local version=$2
+  local unit_prefix=${3:-new}
   local stage="$fixture/stage"
   mkdir -p "$fixture/release" "$stage/public" "$stage/ops"
   printf 'new application\n' > "$stage/app.jar"
@@ -178,7 +180,7 @@ build_release() {
   printf '#!/bin/sh\nprintf "new updater\\n"\n' > "$stage/ops/update.sh"
   chmod 0755 "$stage/ops/update.sh"
   for name in kaidi-finance.service kaidi-update.service kaidi-update.path; do
-    printf 'new %s\n' "$name" > "$stage/ops/$name"
+    printf '%s %s\n' "$unit_prefix" "$name" > "$stage/ops/$name"
   done
 
   local artifact="kaidi-finance-$version.tar.gz"
@@ -272,6 +274,7 @@ run_update() {
     MOCK_RELEASE_ORIGIN="${FIXTURE_RELEASE_ORIGIN:-https://release.fixture.invalid}" \
     MOCK_EXPECT_RELEASE_TOKEN="${FIXTURE_RELEASE_TOKEN-}" \
     MOCK_SYSTEMCTL_LOG="$fixture/systemctl.log" \
+    MOCK_UPDATE_PATH_START="${MOCK_UPDATE_PATH_START:-success}" \
     KAIDI_SERVICE_USER="$(id -un)" \
     KAIDI_SERVICE_GROUP="$(id -gn)" \
     KAIDI_APP_ROOT="$fixture/app" \
@@ -368,6 +371,41 @@ assert_success_case() {
   [ "$(mode_of "$fixture/app/current/ops/update.sh")" = 750 ] || fail 'release updater mode is not 0750'
 }
 
+assert_identical_systemd_operations_case() {
+  local fixture="$WORK/identical-systemd"
+  local version='1.0.0-preview.2'
+  mkdir -p "$fixture"
+  write_mock_commands "$fixture/mock-bin"
+  build_release "$fixture" "$version" old
+  prepare_installation "$fixture" "$version"
+
+  download_and_prepare_install "$fixture" "$version"
+  : > "$fixture/systemctl.log"
+  run_update "$fixture" success
+  [ "$(readlink "$fixture/app/current")" = "$fixture/app/releases/$version" ] \
+    || fail 'identical systemd case did not activate the new application'
+  ! grep -qx 'daemon-reload' "$fixture/systemctl.log" \
+    || fail 'identical systemd units triggered an unnecessary daemon reload'
+}
+
+assert_update_path_failure_keeps_application_case() {
+  local fixture="$WORK/path-watcher-failure"
+  local version='1.0.0-preview.2'
+  mkdir -p "$fixture"
+  write_mock_commands "$fixture/mock-bin"
+  build_release "$fixture" "$version"
+  prepare_installation "$fixture" "$version"
+
+  download_and_prepare_install "$fixture" "$version"
+  MOCK_UPDATE_PATH_START=fail run_update "$fixture" success
+  [ "$(readlink "$fixture/app/current")" = "$fixture/app/releases/$version" ] \
+    || fail 'path watcher failure rolled back a healthy application'
+  [ "$(jq -r '.state' "$fixture/state/status.json")" = SUCCEEDED ] \
+    || fail 'path watcher failure did not preserve successful application state'
+  grep -Fq 'automatic update watcher could not be started' "$fixture/state/status.json" \
+    || fail 'path watcher failure did not preserve its diagnostic'
+}
+
 assert_rollback_case() {
   local fixture="$WORK/rollback"
   local version='1.0.0-preview.2'
@@ -480,6 +518,8 @@ assert_install_without_verified_cache_rejected() {
 }
 
 assert_success_case
+assert_identical_systemd_operations_case
+assert_update_path_failure_keeps_application_case
 assert_rollback_case
 assert_download_failure_case
 assert_database_failure_case