[gtk/matthiasc/for-master] Add a test for refcounts under reordering

[Matthias Clasen <matthiasc src gnome org>]

commit fc42a0696e9b71e4012bf43852facb6446c6cd77
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat May 9 19:23:29 2020 -0400

    Add a test for refcounts under reordering
    
    It turns out that we have a ref leak at the very
    core of our dom model :( gtk_widget_insert_before/after
    leak a reference if the widget was already under
    the same parent. This is something that GtkBox
    frequently does. It shows up e.g. when packing
    widgets at the end in a headerbar.

 testsuite/gtk/widgetorder.c | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)
---
diff --git a/testsuite/gtk/widgetorder.c b/testsuite/gtk/widgetorder.c
index 01a885a6df..c0ffafaeac 100644
--- a/testsuite/gtk/widgetorder.c
+++ b/testsuite/gtk/widgetorder.c
@@ -545,7 +545,45 @@ no_loop (void)
   g_assert (gtk_widget_get_next_sibling (l2) == NULL);
 }
 
-int main (int argc, char **argv)
+static void
+reorder_refcount (void)
+{
+  GtkWidget *p = gtk_label_new ("");
+  GtkWidget *l1 = gtk_label_new ("");
+  GtkWidget *l2 = gtk_label_new ("");
+
+  g_assert (g_object_is_floating (l1));
+  g_assert (G_OBJECT (l1)->ref_count == 1);
+
+  gtk_widget_set_parent (l1, p);
+
+  g_assert (!g_object_is_floating (l1));
+  g_assert (G_OBJECT (l1)->ref_count == 1);
+
+  g_assert (g_object_is_floating (l2));
+  g_assert (G_OBJECT (l2)->ref_count == 1);
+
+  gtk_widget_set_parent (l2, p);
+
+  g_assert (!g_object_is_floating (l2));
+  g_assert (G_OBJECT (l2)->ref_count == 1);
+
+  g_assert (gtk_widget_get_next_sibling (l1) == l2);
+
+  gtk_widget_insert_before (l2, p, l1);
+
+  g_assert (gtk_widget_get_prev_sibling (l1) == l2);
+
+  g_assert (G_OBJECT (l1)->ref_count == 1);
+  g_assert (G_OBJECT (l2)->ref_count == 1);
+
+  gtk_widget_unparent (l1);
+  gtk_widget_unparent (l2);
+  g_object_unref (g_object_ref_sink (p));
+}
+
+int
+main (int argc, char **argv)
 {
   gtk_init ();
   g_test_init (&argc, &argv, NULL);
@@ -565,6 +603,7 @@ int main (int argc, char **argv)
   g_test_add_func ("/widgetorder/same-after", same_after);
   g_test_add_func ("/widgetorder/same-before", same_before);
   g_test_add_func ("/widgetorder/no-loop", no_loop);
+  g_test_add_func ("/widgetorder/reorder-refcount", reorder_refcount);
 
   return g_test_run ();
 }