qemuagenttest: Check invalid response in shutdown test

The shutdown test utilizes waiting for condition to exit the test. This
addition will return an error for the shutdown command to see if the
condition waiting code will not hang.

tests/qemuagenttest.c

@@ -324,6 +324,29 @@ testQemuAgentShutdown(const void *data)
                           QEMU_AGENT_SHUTDOWN_REBOOT) < 0)
         goto cleanup;
 
+    /* check negative response, so that we can verify that the agent breaks
+     * out from sleep */
+
+    if (qemuMonitorTestAddAgentSyncResponse(test) < 0)
+        goto cleanup;
+
+    if (qemuMonitorTestAddItem(test, "guest-shutdown",
+                               "{\"error\":"
+                               "    {\"class\":\"CommandDisabled\","
+                               "     \"desc\":\"The command guest-shutdown has "
+                                               "been disabled for this instance\","
+                               "     \"data\":{\"name\":\"guest-shutdown\"}"
+                               "    }"
+                               "}") < 0)
+        goto cleanup;
+
+    if (qemuAgentShutdown(qemuMonitorTestGetAgent(test),
+                          QEMU_AGENT_SHUTDOWN_REBOOT) != -1) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       "agent shutdown command should have failed");
+        goto cleanup;
+    }
+
     ret = 0;
 
 cleanup: