tests: Test QOM interface casting

Add basic regression testing for QOM Interface usage.
Test checks casting to interface type/class for following cases:
  - interface implementation in leaf class
  - interface implementation in intermediate (parent) class

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>

tests/check-qom-interface.c

@@ -0,0 +1,105 @@
+/*
+ * QOM interface test.
+ *
+ * Copyright (C) 2013 Red Hat Inc.
+ *
+ * Authors:
+ *  Igor Mammedov <imammedo@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ */
+#include <glib.h>
+
+#include "qom/object.h"
+#include "qemu/module.h"
+
+
+#define TYPE_TEST_IF "test-interface"
+#define TEST_IF_CLASS(klass) \
+     OBJECT_CLASS_CHECK(TestIfClass, (klass), TYPE_TEST_IF)
+#define TEST_IF_GET_CLASS(obj) \
+     OBJECT_GET_CLASS(TestIfClass, (obj), TYPE_TEST_IF)
+#define TEST_IF(obj) \
+     INTERFACE_CHECK(TestIf, (obj), TYPE_TEST_IF)
+
+typedef struct TestIf {
+    Object parent_obj;
+} TestIf;
+
+typedef struct TestIfClass {
+    InterfaceClass parent_class;
+
+    uint32_t test;
+} TestIfClass;
+
+static const TypeInfo test_if_info = {
+    .name          = TYPE_TEST_IF,
+    .parent        = TYPE_INTERFACE,
+    .class_size = sizeof(TestIfClass),
+};
+
+#define PATTERN 0xFAFBFCFD
+
+static void test_class_init(ObjectClass *oc, void *data)
+{
+    TestIfClass *tc = TEST_IF_CLASS(oc);
+
+    g_assert(tc);
+    tc->test = PATTERN;
+}
+
+#define TYPE_DIRECT_IMPL "direct-impl"
+
+static const TypeInfo direct_impl_info = {
+    .name = TYPE_DIRECT_IMPL,
+    .parent = TYPE_OBJECT,
+    .class_init = test_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_TEST_IF },
+        { }
+    }
+};
+
+#define TYPE_INTERMEDIATE_IMPL "intermediate-impl"
+
+static const TypeInfo intermediate_impl_info = {
+    .name = TYPE_INTERMEDIATE_IMPL,
+    .parent = TYPE_DIRECT_IMPL,
+};
+
+static void test_interface_impl(const char *type)
+{
+    Object *obj = object_new(type);
+    TestIf *iobj = TEST_IF(obj);
+    TestIfClass *ioc = TEST_IF_GET_CLASS(iobj);
+
+    g_assert(iobj);
+    g_assert(ioc->test == PATTERN);
+}
+
+static void interface_direct_test(void)
+{
+    test_interface_impl(TYPE_DIRECT_IMPL);
+}
+
+static void interface_intermediate_test(void)
+{
+    test_interface_impl(TYPE_INTERMEDIATE_IMPL);
+}
+
+int main(int argc, char **argv)
+{
+    g_test_init(&argc, &argv, NULL);
+
+    module_call_init(MODULE_INIT_QOM);
+    type_register_static(&test_if_info);
+    type_register_static(&direct_impl_info);
+    type_register_static(&intermediate_impl_info);
+
+    g_test_add_func("/qom/interface/direct_impl", interface_direct_test);
+    g_test_add_func("/qom/interface/intermediate_impl",
+                    interface_intermediate_test);
+
+    return g_test_run();
+}