diff --git a/tests/drive_del-test.c b/tests/drive_del-test.c
index 673c10140f7f12bd35ddf0a2cff36351168cbeaa..4a1a0889c8de29eed9571d618a4cd9f3c538b8c3 100644
--- a/tests/drive_del-test.c
+++ b/tests/drive_del-test.c
@@ -67,7 +67,6 @@ static void test_after_failed_device_add(void)
 {
     char driver[32];
     QDict *response;
-    QDict *error;
 
     snprintf(driver, sizeof(driver), "virtio-blk-%s",
              qvirtio_get_dev_type());
@@ -83,9 +82,7 @@ static void test_after_failed_device_add(void)
                    "   'drive': 'drive0'"
                    "}}", driver);
     g_assert(response);
-    error = qdict_get_qdict(response, "error");
-    g_assert_cmpstr(qdict_get_try_str(error, "class"), ==, "GenericError");
-    qobject_unref(response);
+    qmp_assert_error_class(response, "GenericError");
 
     /* Delete the drive */
     drive_del();
diff --git a/tests/libqtest.c b/tests/libqtest.c
index d635c5bea0cb0f03778cd67448925515212d1c90..2cd573664228f6fd7ee1a64d608a5b331525e6aa 100644
--- a/tests/libqtest.c
+++ b/tests/libqtest.c
@@ -1194,3 +1194,14 @@ bool qmp_rsp_is_err(QDict *rsp)
     qobject_unref(rsp);
     return !!error;
 }
+
+void qmp_assert_error_class(QDict *rsp, const char *class)
+{
+    QDict *error = qdict_get_qdict(rsp, "error");
+
+    g_assert_cmpstr(qdict_get_try_str(error, "class"), ==, class);
+    g_assert_nonnull(qdict_get_try_str(error, "desc"));
+    g_assert(!qdict_haskey(rsp, "return"));
+
+    qobject_unref(rsp);
+}
diff --git a/tests/libqtest.h b/tests/libqtest.h
index 36d5caecd4524a0673f06899c19c3aaad3f5383a..ed88ff99d551a382f6eb244123a0206945ea79f6 100644
--- a/tests/libqtest.h
+++ b/tests/libqtest.h
@@ -1004,4 +1004,13 @@ void qtest_qmp_device_del(const char *id);
  */
 bool qmp_rsp_is_err(QDict *rsp);
 
+/**
+ * qmp_assert_error_class:
+ * @rsp: QMP response to check for error
+ * @class: an error class
+ *
+ * Assert the response has the given error class and discard @rsp.
+ */
+void qmp_assert_error_class(QDict *rsp, const char *class);
+
 #endif
diff --git a/tests/qmp-test.c b/tests/qmp-test.c
index 4ae22454844804dc85e97d6b58496cc50ff733ea..b3472281ae2c03bdf2732ec55668ae24b45c3982 100644
--- a/tests/qmp-test.c
+++ b/tests/qmp-test.c
@@ -21,15 +21,6 @@
 
 const char common_args[] = "-nodefaults -machine none";
 
-static const char *get_error_class(QDict *resp)
-{
-    QDict *error = qdict_get_qdict(resp, "error");
-    const char *desc = qdict_get_try_str(error, "desc");
-
-    g_assert(desc);
-    return error ? qdict_get_try_str(error, "class") : NULL;
-}
-
 static void test_version(QObject *version)
 {
     Visitor *v;
@@ -42,15 +33,12 @@ static void test_version(QObject *version)
     visit_free(v);
 }
 
-static bool recovered(QTestState *qts)
+static void assert_recovered(QTestState *qts)
 {
     QDict *resp;
-    bool ret;
 
     resp = qtest_qmp(qts, "{ 'execute': 'no-such-cmd' }");
-    ret = !strcmp(get_error_class(resp), "CommandNotFound");
-    qobject_unref(resp);
-    return ret;
+    qmp_assert_error_class(resp, "CommandNotFound");
 }
 
 static void test_malformed(QTestState *qts)
@@ -60,73 +48,61 @@ static void test_malformed(QTestState *qts)
     /* syntax error */
     qtest_qmp_send_raw(qts, "{]\n");
     resp = qtest_qmp_receive(qts);
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
-    qobject_unref(resp);
-    g_assert(recovered(qts));
+    qmp_assert_error_class(resp, "GenericError");
+    assert_recovered(qts);
 
     /* lexical error: impossible byte outside string */
     qtest_qmp_send_raw(qts, "{\xFF");
     resp = qtest_qmp_receive(qts);
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
-    qobject_unref(resp);
-    g_assert(recovered(qts));
+    qmp_assert_error_class(resp, "GenericError");
+    assert_recovered(qts);
 
     /* lexical error: funny control character outside string */
     qtest_qmp_send_raw(qts, "{\x01");
     resp = qtest_qmp_receive(qts);
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
-    qobject_unref(resp);
-    g_assert(recovered(qts));
+    qmp_assert_error_class(resp, "GenericError");
+    assert_recovered(qts);
 
     /* lexical error: impossible byte in string */
     qtest_qmp_send_raw(qts, "{'bad \xFF");
     resp = qtest_qmp_receive(qts);
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
-    qobject_unref(resp);
-    g_assert(recovered(qts));
+    qmp_assert_error_class(resp, "GenericError");
+    assert_recovered(qts);
 
     /* lexical error: control character in string */
     qtest_qmp_send_raw(qts, "{'execute': 'nonexistent', 'id':'\n");
     resp = qtest_qmp_receive(qts);
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
-    qobject_unref(resp);
-    g_assert(recovered(qts));
+    qmp_assert_error_class(resp, "GenericError");
+    assert_recovered(qts);
 
     /* lexical error: interpolation */
     qtest_qmp_send_raw(qts, "%%p\n");
     /* two errors, one for "%", one for "p" */
     resp = qtest_qmp_receive(qts);
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
-    qobject_unref(resp);
+    qmp_assert_error_class(resp, "GenericError");
     resp = qtest_qmp_receive(qts);
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
-    qobject_unref(resp);
-    g_assert(recovered(qts));
+    qmp_assert_error_class(resp, "GenericError");
+    assert_recovered(qts);
 
     /* Not even a dictionary */
     resp = qtest_qmp(qts, "null");
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
-    qobject_unref(resp);
+    qmp_assert_error_class(resp, "GenericError");
 
     /* No "execute" key */
     resp = qtest_qmp(qts, "{}");
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
-    qobject_unref(resp);
+    qmp_assert_error_class(resp, "GenericError");
 
     /* "execute" isn't a string */
     resp = qtest_qmp(qts, "{ 'execute': true }");
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
-    qobject_unref(resp);
+    qmp_assert_error_class(resp, "GenericError");
 
     /* "arguments" isn't a dictionary */
     resp = qtest_qmp(qts, "{ 'execute': 'no-such-cmd', 'arguments': [] }");
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
-    qobject_unref(resp);
+    qmp_assert_error_class(resp, "GenericError");
 
     /* extra key */
     resp = qtest_qmp(qts, "{ 'execute': 'no-such-cmd', 'extra': true }");
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
-    qobject_unref(resp);
+    qmp_assert_error_class(resp, "GenericError");
 }
 
 static void test_qmp_protocol(void)
@@ -148,8 +124,7 @@ static void test_qmp_protocol(void)
 
     /* Test valid command before handshake */
     resp = qtest_qmp(qts, "{ 'execute': 'query-version' }");
-    g_assert_cmpstr(get_error_class(resp), ==, "CommandNotFound");
-    qobject_unref(resp);
+    qmp_assert_error_class(resp, "CommandNotFound");
 
     /* Test malformed commands before handshake */
     test_malformed(qts);
@@ -162,8 +137,7 @@ static void test_qmp_protocol(void)
 
     /* Test repeated handshake */
     resp = qtest_qmp(qts, "{ 'execute': 'qmp_capabilities' }");
-    g_assert_cmpstr(get_error_class(resp), ==, "CommandNotFound");
-    qobject_unref(resp);
+    qmp_assert_error_class(resp, "CommandNotFound");
 
     /* Test valid command */
     resp = qtest_qmp(qts, "{ 'execute': 'query-version' }");
@@ -182,9 +156,8 @@ static void test_qmp_protocol(void)
 
     /* Test command failure with 'id' */
     resp = qtest_qmp(qts, "{ 'execute': 'human-monitor-command', 'id': 2 }");
-    g_assert_cmpstr(get_error_class(resp), ==, "GenericError");
     g_assert_cmpint(qdict_get_int(resp, "id"), ==, 2);
-    qobject_unref(resp);
+    qmp_assert_error_class(resp, "GenericError");
 
     qtest_quit(qts);
 }
diff --git a/tests/test-qga.c b/tests/test-qga.c
index f69cdf6c03f235797ca0e9980b2f3f67e39f0775..3d6377436a10f3e242a3e4d9c97a135d0164e7db 100644
--- a/tests/test-qga.c
+++ b/tests/test-qga.c
@@ -244,17 +244,12 @@ static void test_qga_invalid_id(gconstpointer fix)
 static void test_qga_invalid_oob(gconstpointer fix)
 {
     const TestFixture *fixture = fix;
-    QDict *ret, *error;
-    const char *class;
+    QDict *ret;
 
     ret = qmp_fd(fixture->fd, "{'exec-oob': 'guest-ping'}");
     g_assert_nonnull(ret);
 
-    error = qdict_get_qdict(ret, "error");
-    class = qdict_get_try_str(error, "class");
-    g_assert_cmpstr(class, ==, "GenericError");
-
-    qobject_unref(ret);
+    qmp_assert_error_class(ret, "GenericError");
 }
 
 static void test_qga_invalid_args(gconstpointer fix)