From f7b249a65baeeb8f48ebfc6ca98265f23cd26d57 Mon Sep 17 00:00:00 2001
From: pasinskim <marcin.pasinski@northern.tech>
Date: Thu, 2 Jul 2026 09:25:07 +0200
Subject: [PATCH] test: capture the QEMU client serial console on failure

The failure teardown only prints device output over SSH, which is empty when
the device is unreachable -- which is exactly the "Device never rebooted"
failure mode (a hung guest reset). Capture the client's serial console via
"docker compose logs" (which works without SSH) into the per-test logs, so the
guest's actual reboot behaviour (e.g. "reboot: machine restart" followed by
silence) is visible directly in CI artifacts.

Changelog: None
Signed-off-by: pasinskim <marcin.pasinski@northern.tech>
---
 tests/conftest.py | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/tests/conftest.py b/tests/conftest.py
index fcd00c2f4..c62c80a54 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -346,6 +346,49 @@ def pytest_exception_interact(node, call, report):
                         f"database snapshot captured; import using: mongorestore --archive={log.TEST_LOGS_PATH}/{node.name}.bson"
                     )
 
+                # Capture the QEMU client's serial console. "docker compose
+                # logs" of the client works even when the device is unreachable
+                # over SSH -- which is exactly the "Device never rebooted"
+                # failure mode -- so it is the only record of what the guest
+                # actually did on reboot (the SSH-based logs below are empty
+                # when the guest is dead).
+                for svc in ("mender-client", "mender-client-docker-addons"):
+                    try:
+                        console = subprocess.run(
+                            [
+                                "docker",
+                                "compose",
+                                "-p",
+                                env.name,
+                                "logs",
+                                "--no-color",
+                                "--no-log-prefix",
+                                svc,
+                            ],
+                            env=dict(
+                                **os.environ,
+                                COMPOSE_FILE=":".join(env.docker_compose_files),
+                            ),
+                            capture_output=True,
+                            text=True,
+                            timeout=120,
+                        ).stdout
+                    except Exception as ex:
+                        logger.warning("failed to capture %s console: %s", svc, ex)
+                        continue
+                    if console.strip():
+                        console_path = (
+                            f"{log.TEST_LOGS_PATH}/{node.name}_{svc}_console.log"
+                        )
+                        with open(console_path, "w") as fh:
+                            fh.write(console)
+                        logger.info(
+                            "captured %s serial console -> %s (%d bytes)",
+                            svc,
+                            console_path,
+                            len(console),
+                        )
+
         # If we have devices (or groups) try to print deployment and systemd logs
         if devices is []:
             logger.info("Could not find devices in test environment, no printing logs")