qom-test: Test QOM properties

Recursively walk all properties under /machine and try to retrieve their
value. This is a regression test for link<> properties and the
DeviceState::hotpluggable property.

Cf. be2f78b6b0 and
    1a37eca107

Signed-off-by: Andreas Färber <afaerber@suse.de>

tests/qom-test.c

@@ -10,6 +10,7 @@
 #include <glib.h>
 #include <string.h>
 
+#include "qemu-common.h"
 #include "libqtest.h"
 #include "qemu/osdep.h"
 #include "qapi/qmp/types.h"
@@ -43,6 +44,40 @@ static bool is_blacklisted(const char *arch, const char *mach)
     return false;
 }
 
+static void test_properties(const char *path)
+{
+    char *child_path;
+    QDict *response, *tuple;
+    QList *list;
+    QListEntry *entry;
+
+    g_test_message("Obtaining properties of %s", path);
+    response = qmp("{ 'execute': 'qom-list',"
+                   "  'arguments': { 'path': '%s' } }", path);
+    g_assert(response);
+
+    g_assert(qdict_haskey(response, "return"));
+    list = qobject_to_qlist(qdict_get(response, "return"));
+    QLIST_FOREACH_ENTRY(list, entry) {
+        tuple = qobject_to_qdict(qlist_entry_obj(entry));
+        if (strstart(qdict_get_str(tuple, "type"), "child<", NULL)) {
+            child_path = g_strdup_printf("%s/%s",
+                                         path, qdict_get_str(tuple, "name"));
+            test_properties(child_path);
+            g_free(child_path);
+        } else {
+            const char *prop = qdict_get_str(tuple, "name");
+            g_test_message("Testing property %s.%s", path, prop);
+            response = qmp("{ 'execute': 'qom-get',"
+                           "  'arguments': { 'path': '%s',"
+                           "                 'property': '%s' } }",
+                           path, prop);
+            /* qom-get may fail but should not, e.g., segfault. */
+            g_assert(response);
+        }
+    }
+}
+
 static void test_machine(gconstpointer data)
 {
     const char *machine = data;
@@ -51,8 +86,12 @@ static void test_machine(gconstpointer data)
 
     args = g_strdup_printf("-machine %s", machine);
     qtest_start(args);
+
+    test_properties("/machine");
+
     response = qmp("{ 'execute': 'quit' }");
     g_assert(qdict_haskey(response, "return"));
+
     qtest_end();
     g_free(args);
 }