The form did work as expected with Orbeon Forms but doesn’t happen to work with neither betterFORM not XSLTForms and I have sent reports accordingly on the Betterform-users and xsltforms-support mailing lists.
These issues are really blocking to pursue this idea which would allow to test control’s statuses. I don’t see what can be possibly wrong in the code that I have written and do hope that we’ll find a workaround or get fixes soon.
While doing these tests I have also noticed that betterFORM was not reacting like Orbeon Forms and XSLTForms when changing the selection in xf:select controls: with betterFORM the value is not updated in the instance until the focus leaves the control while it is immediately updated for Orebon Forms and XSLTForms.
Developing mostly for Orbeon Forms this behavior seemed natural to me but the W3C recommendation clearly states that betterFORM is right when there is no @incremental=”true” attribute. Here again I have reported the issues on Xsltforms-support and orbeon-forms.
This second issue is minor and doesn’t really impact XForms Unit but this clearly show what happens when you try to develop forms that should be inter-operable in the three main open source XForms implementation: even simple forms are a nightmare like here where I had to fill four reports!