[mutter] test-runner: Wait before finding MetaWindow when showing

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 8d84449941b189f9fe5d4be0a50699d3c6e00ddc
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Jun 5 00:03:00 2020 +0200

    test-runner: Wait before finding MetaWindow when showing
    
    A "show" command calls gtk_window_show() and gdk_display_sync(), then
    returns. This means that the X11 window objects are guaranteed to have
    been created in the X11 server.
    
    After that, the test runner will look up the window's associated
    MetaWindow and wait for it to be shown.
    
    What this doesn't account for is if mutter didn't get enough CPU time to
    see the new window. When this happens, the 'default-size' stacking test
    sometimes failed after hiding and showing the X11 window.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1288

 src/tests/test-runner.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/src/tests/test-runner.c b/src/tests/test-runner.c
index f1c605ad6d..577c4dcae7 100644
--- a/src/tests/test-runner.c
+++ b/src/tests/test-runner.c
@@ -572,6 +572,9 @@ test_case_do (TestCase *test,
       if (!test_client_do (client, error, argv[0], window_id, NULL))
         return FALSE;
 
+      if (!test_case_wait (test, error))
+        return FALSE;
+
       MetaWindow *window = test_client_find_window (client, window_id, error);
       if (!window)
         return FALSE;