test: add test for GetUnitByPID() D-Bus method

For issue #34104.

diff --git a/test/units/TEST-07-PID1.issue-34104.sh b/test/units/TEST-07-PID1.issue-34104.sh
new file mode 100755 (executable)
index 0000000..777065c
--- /dev/null
+++ b/test/units/TEST-07-PID1.issue-34104.sh
@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: LGPL-2.1-or-later
+set -eux
+set -o pipefail
+
+# shellcheck source=test/units/util.sh
+. "$(dirname "$0")"/util.sh
+
+systemd-run -u test-sleep.service sleep 1h
+SLEEP_PID=$(systemctl show test-sleep.service -p ExecMainPID --value)
+SLEEP_OBJECT=$(busctl call org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager GetUnitByPID "u" "$SLEEP_PID")
+assert_eq "$SLEEP_OBJECT" "o \"/org/freedesktop/systemd1/unit/test_2dsleep_2eservice\""
+systemctl stop test-sleep.service
+
+# For https://github.com/systemd/systemd/issues/34104
+for ((i = 10000; i < 11000; i++)); do
+    busctl call org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager GetUnitByPID "u" "$i" || :
+done
+
+exit 0