test: Add integration test for signal handling warnings/errors

tests/integration_tests/modules/test_power_state_change.py

@@ -12,7 +12,10 @@
 from tests.integration_tests.instances import IntegrationInstance
 from tests.integration_tests.integration_settings import PLATFORM
 from tests.integration_tests.releases import IS_UBUNTU
-from tests.integration_tests.util import verify_ordered_items_in_text
+from tests.integration_tests.util import (
+    verify_clean_boot,
+    verify_ordered_items_in_text,
+)
 
 USER_DATA = """\
 #cloud-config
@@ -83,6 +86,7 @@ def test_poweroff(
                 instance.instance.start(wait=True)
             log = instance.read_from_file("/var/log/cloud-init.log")
             assert _can_connect(instance)
+            verify_clean_boot(instance)
         lines_to_check = [
             "Running module power_state_change",
             expected,

tests/integration_tests/test_signal_handler.py

@@ -0,0 +1,21 @@
+import pytest
+
+from tests.integration_tests.instances import IntegrationInstance
+from tests.integration_tests.util import verify_clean_boot
+
+USER_DATA = """\
+#cloud-config
+runcmd:
+ - reboot
+"""
+
+
+@pytest.mark.user_data(USER_DATA)
+def test_no_warnings(client: IntegrationInstance):
+    """Test that the signal handler does not log errors on reboot.
+
+    Note that for single process boots, `Conflicts=shutdown.target` will
+    prevent the shutdown from happening before the cloud-init process has
+    exited.
+    """
+    verify_clean_boot(client)