diff --git a/tests/libqos/pci.c b/tests/libqos/pci.c
index 2dcdead..df1f98e 100644
--- a/tests/libqos/pci.c
+++ b/tests/libqos/pci.c
@@ -394,21 +394,6 @@ QPCIBar qpci_legacy_iomap(QPCIDevice *dev, uint16_t addr)
 void qpci_plug_device_test(const char *driver, const char *id,
                            uint8_t slot, const char *opts)
 {
-    QDict *response;
-    char *cmd;
-
-    cmd = g_strdup_printf("{'execute': 'device_add',"
-                          " 'arguments': {"
-                          "   'driver': '%s',"
-                          "   'addr': '%d',"
-                          "   %s%s"
-                          "   'id': '%s'"
-                          "}}", driver, slot,
-                          opts ? opts : "", opts ? "," : "",
-                          id);
-    response = qmp(cmd);
-    g_free(cmd);
-    g_assert(response);
-    g_assert(!qdict_haskey(response, "error"));
-    QDECREF(response);
+    qtest_qmp_device_add(driver, id, "'addr': '%d'%s%s", slot,
+                         opts ? ", " : "", opts ? opts : "");
 }
diff --git a/tests/libqos/usb.c b/tests/libqos/usb.c
index 0cdfaec..2a47604 100644
--- a/tests/libqos/usb.c
+++ b/tests/libqos/usb.c
@@ -40,34 +40,16 @@ void uhci_port_test(struct qhc *hc, int port, uint16_t expect)
 void usb_test_hotplug(const char *hcd_id, const int port,
                       void (*port_check)(void))
 {
-    QDict *response;
-    char  *cmd;
+    char  *id = g_strdup_printf("usbdev%d", port);
 
-    cmd = g_strdup_printf("{'execute': 'device_add',"
-                          " 'arguments': {"
-                          "   'driver': 'usb-tablet',"
-                          "   'port': '%d',"
-                          "   'bus': '%s.0',"
-                          "   'id': 'usbdev%d'"
-                          "}}", port, hcd_id, port);
-    response = qmp(cmd);
-    g_free(cmd);
-    g_assert(response);
-    g_assert(!qdict_haskey(response, "error"));
-    QDECREF(response);
+    qtest_qmp_device_add("usb-tablet", id, "'port': '%d', 'bus': '%s.0'",
+                         port, hcd_id);
 
     if (port_check) {
         port_check();
     }
 
-    cmd = g_strdup_printf("{'execute': 'device_del',"
-                           " 'arguments': {"
-                           "   'id': 'usbdev%d'"
-                           "}}", port);
-    response = qmp(cmd);
-    g_free(cmd);
-    g_assert(response);
-    g_assert(qdict_haskey(response, "event"));
-    g_assert(!strcmp(qdict_get_str(response, "event"), "DEVICE_DELETED"));
-    QDECREF(response);
+    qtest_qmp_device_del(id);
+
+    g_free(id);
 }
diff --git a/tests/libqtest.c b/tests/libqtest.c
index b9a1f18..0c12b38 100644
--- a/tests/libqtest.c
+++ b/tests/libqtest.c
@@ -987,3 +987,78 @@ void qtest_cb_for_every_machine(void (*cb)(const char *machine))
     qtest_end();
     QDECREF(response);
 }
+
+/*
+ * Generic hot-plugging test via the device_add QMP command.
+ */
+void qtest_qmp_device_add(const char *driver, const char *id, const char *fmt,
+                          ...)
+{
+    QDict *response;
+    char *cmd, *opts = NULL;
+    va_list va;
+
+    if (fmt) {
+        va_start(va, fmt);
+        opts = g_strdup_vprintf(fmt, va);
+        va_end(va);
+    }
+
+    cmd = g_strdup_printf("{'execute': 'device_add',"
+                          " 'arguments': { 'driver': '%s', 'id': '%s'%s%s }}",
+                          driver, id, opts ? ", " : "", opts ? opts : "");
+    g_free(opts);
+
+    response = qmp(cmd);
+    g_free(cmd);
+    g_assert(response);
+    g_assert(!qdict_haskey(response, "event")); /* We don't expect any events */
+    g_assert(!qdict_haskey(response, "error"));
+    QDECREF(response);
+}
+
+/*
+ * Generic hot-unplugging test via the device_del QMP command.
+ * Device deletion will get one response and one event. For example:
+ *
+ * {'execute': 'device_del','arguments': { 'id': 'scsi-hd'}}
+ *
+ * will get this one:
+ *
+ * {"timestamp": {"seconds": 1505289667, "microseconds": 569862},
+ *  "event": "DEVICE_DELETED", "data": {"device": "scsi-hd",
+ *  "path": "/machine/peripheral/scsi-hd"}}
+ *
+ * and this one:
+ *
+ * {"return": {}}
+ *
+ * But the order of arrival may vary - so we've got to detect both.
+ */
+void qtest_qmp_device_del(const char *id)
+{
+    QDict *response1, *response2, *event = NULL;
+    char *cmd;
+
+    cmd = g_strdup_printf("{'execute': 'device_del',"
+                          " 'arguments': { 'id': '%s' }}", id);
+    response1 = qmp(cmd);
+    g_free(cmd);
+    g_assert(response1);
+    g_assert(!qdict_haskey(response1, "error"));
+
+    response2 = qmp("");
+    g_assert(response2);
+    g_assert(!qdict_haskey(response2, "error"));
+
+    if (qdict_haskey(response1, "event")) {
+        event = response1;
+    } else if (qdict_haskey(response2, "event")) {
+        event = response2;
+    }
+    g_assert(event);
+    g_assert_cmpstr(qdict_get_str(event, "event"), ==, "DEVICE_DELETED");
+
+    QDECREF(response1);
+    QDECREF(response2);
+}
diff --git a/tests/libqtest.h b/tests/libqtest.h
index 3ae5709..44803d7 100644
--- a/tests/libqtest.h
+++ b/tests/libqtest.h
@@ -927,4 +927,23 @@ QDict *qmp_fd(int fd, const char *fmt, ...);
  */
 void qtest_cb_for_every_machine(void (*cb)(const char *machine));
 
+/**
+ * qtest_qmp_device_add:
+ * @driver: Name of the device that should be added
+ * @id: Identification string
+ * @fmt: printf-like format string for further options to device_add
+ *
+ * Generic hot-plugging test via the device_add QMP command.
+ */
+void qtest_qmp_device_add(const char *driver, const char *id, const char *fmt,
+                          ...) GCC_FMT_ATTR(3, 4);
+
+/**
+ * qtest_qmp_device_del:
+ * @id: Identification string
+ *
+ * Generic hot-unplugging test via the device_del QMP command.
+ */
+void qtest_qmp_device_del(const char *id);
+
 #endif
diff --git a/tests/usb-hcd-uhci-test.c b/tests/usb-hcd-uhci-test.c
index 5b500fe..62e0c78 100644
--- a/tests/usb-hcd-uhci-test.c
+++ b/tests/usb-hcd-uhci-test.c
@@ -48,31 +48,9 @@ static void test_uhci_hotplug(void)
 
 static void test_usb_storage_hotplug(void)
 {
-    QDict *response;
+    qtest_qmp_device_add("usb-storage", "usbdev0", "'drive': 'drive0'");
 
-    response = qmp("{'execute': 'device_add',"
-                   " 'arguments': {"
-                   "   'driver': 'usb-storage',"
-                   "   'drive': 'drive0',"
-                   "   'id': 'usbdev0'"
-                   "}}");
-    g_assert(response);
-    g_assert(!qdict_haskey(response, "error"));
-    QDECREF(response);
-
-    response = qmp("{'execute': 'device_del',"
-                           " 'arguments': {"
-                           "   'id': 'usbdev0'"
-                           "}}");
-    g_assert(response);
-    g_assert(!qdict_haskey(response, "error"));
-    QDECREF(response);
-
-    response = qmp("");
-    g_assert(response);
-    g_assert(qdict_haskey(response, "event"));
-    g_assert(!strcmp(qdict_get_str(response, "event"), "DEVICE_DELETED"));
-    QDECREF(response);
+    qtest_qmp_device_del("usbdev0");
 }
 
 int main(int argc, char **argv)
diff --git a/tests/usb-hcd-xhci-test.c b/tests/usb-hcd-xhci-test.c
index 031764d..9c14e30 100644
--- a/tests/usb-hcd-xhci-test.c
+++ b/tests/usb-hcd-xhci-test.c
@@ -23,59 +23,16 @@ static void test_xhci_hotplug(void)
 
 static void test_usb_uas_hotplug(void)
 {
-    QDict *response;
-
-    response = qmp("{'execute': 'device_add',"
-                   " 'arguments': {"
-                   "   'driver': 'usb-uas',"
-                   "   'id': 'uas'"
-                   "}}");
-    g_assert(response);
-    g_assert(!qdict_haskey(response, "error"));
-    QDECREF(response);
-
-    response = qmp("{'execute': 'device_add',"
-                   " 'arguments': {"
-                   "   'driver': 'scsi-hd',"
-                   "   'drive': 'drive0',"
-                   "   'id': 'scsi-hd'"
-                   "}}");
-    g_assert(response);
-    g_assert(!qdict_haskey(response, "error"));
-    QDECREF(response);
+    qtest_qmp_device_add("usb-uas", "uas", NULL);
+    qtest_qmp_device_add("scsi-hd", "scsihd", "'drive': 'drive0'");
 
     /* TODO:
         UAS HBA driver in libqos, to check that
         added disk is visible after BUS rescan
     */
 
-    response = qmp("{'execute': 'device_del',"
-                           " 'arguments': {"
-                           "   'id': 'scsi-hd'"
-                           "}}");
-    g_assert(response);
-    g_assert(!qdict_haskey(response, "error"));
-    QDECREF(response);
-
-    response = qmp("");
-    g_assert(qdict_haskey(response, "event"));
-    g_assert(!strcmp(qdict_get_str(response, "event"), "DEVICE_DELETED"));
-    QDECREF(response);
-
-
-    response = qmp("{'execute': 'device_del',"
-                           " 'arguments': {"
-                           "   'id': 'uas'"
-                           "}}");
-    g_assert(response);
-    g_assert(!qdict_haskey(response, "error"));
-    QDECREF(response);
-
-    response = qmp("");
-    g_assert(response);
-    g_assert(qdict_haskey(response, "event"));
-    g_assert(!strcmp(qdict_get_str(response, "event"), "DEVICE_DELETED"));
-    QDECREF(response);
+    qtest_qmp_device_del("scsihd");
+    qtest_qmp_device_del("uas");
 }
 
 int main(int argc, char **argv)
diff --git a/tests/virtio-scsi-test.c b/tests/virtio-scsi-test.c
index 87a3b6e..d148512 100644
--- a/tests/virtio-scsi-test.c
+++ b/tests/virtio-scsi-test.c
@@ -192,32 +192,12 @@ static void pci_nop(void)
 
 static void hotplug(void)
 {
-    QDict *response;
     QOSState *qs;
 
     qs = qvirtio_scsi_start(
             "-drive id=drv1,if=none,file=null-co://,format=raw");
-    response = qmp("{\"execute\": \"device_add\","
-                   " \"arguments\": {"
-                   "   \"driver\": \"scsi-hd\","
-                   "   \"id\": \"scsi-hd\","
-                   "   \"drive\": \"drv1\""
-                   "}}");
-
-    g_assert(response);
-    g_assert(!qdict_haskey(response, "error"));
-    QDECREF(response);
-
-    response = qmp("{\"execute\": \"device_del\","
-                   " \"arguments\": {"
-                   "   \"id\": \"scsi-hd\""
-                   "}}");
-
-    g_assert(response);
-    g_assert(!qdict_haskey(response, "error"));
-    g_assert(qdict_haskey(response, "event"));
-    g_assert(!strcmp(qdict_get_str(response, "event"), "DEVICE_DELETED"));
-    QDECREF(response);
+    qtest_qmp_device_add("scsi-hd", "scsihd", "'drive': 'drv1'");
+    qtest_qmp_device_del("scsihd");
     qvirtio_scsi_stop(qs);
 }
 
diff --git a/tests/virtio-serial-test.c b/tests/virtio-serial-test.c
index b14d943..7d1517d 100644
--- a/tests/virtio-serial-test.c
+++ b/tests/virtio-serial-test.c
@@ -17,28 +17,9 @@ static void pci_nop(void)
 
 static void hotplug(void)
 {
-    QDict *response;
-
-    response = qmp("{\"execute\": \"device_add\","
-                   " \"arguments\": {"
-                   "   \"driver\": \"virtserialport\","
-                   "   \"id\": \"hp-port\""
-                   "}}");
-
-    g_assert(response);
-    g_assert(!qdict_haskey(response, "error"));
-    QDECREF(response);
-
-    response = qmp("{\"execute\": \"device_del\","
-                   " \"arguments\": {"
-                   "   \"id\": \"hp-port\""
-                   "}}");
-
-    g_assert(response);
-    g_assert(!qdict_haskey(response, "error"));
-    g_assert(qdict_haskey(response, "event"));
-    g_assert(!strcmp(qdict_get_str(response, "event"), "DEVICE_DELETED"));
-    QDECREF(response);
+    qtest_qmp_device_add("virtserialport", "hp-port", NULL);
+
+    qtest_qmp_device_del("hp-port");
 }
 
 int main(int argc, char **argv)
