Giovanni Mascellani (@giomasce) commented about dlls/xactengine3_7/tests/xact3.c:
- notification_desc.flags = 0;
 - notification_desc.pvContext = &prepared_data;
 - hr = IXACT3Engine_RegisterNotification(engine, ¬ification_desc);
 - ok(hr == E_INVALIDARG, "got hr %#lx\n", hr);
 - hr = IXACT3Engine_RegisterNotification(engine, ¬ification_desc);
 - ok(hr == E_INVALIDARG, "got hr %#lx\n", hr);
 - notification_desc.type = 0;
 - notification_desc.flags = 0;
 - notification_desc.pvContext = &prepared_data;
 - hr = IXACT3Engine_RegisterNotification(engine, ¬ification_desc);
 - ok(hr == E_INVALIDARG, "got hr %#lx\n", hr);
 - hr = IXACT3Engine_RegisterNotification(engine, ¬ification_desc);
 - ok(hr == E_INVALIDARG, "got hr %#lx\n", hr);
 
Isn't this the same call just repeated four times? I don't get what it is useful for (beside the first time).