How to simulate service proxy on form?

On the form I have a service proxy that does not work in my environment. How can i mock it?

You can simulate a service proxy using tab ‘symulacja’ (1) which is in the details od external data source ‘źródło danych zewnętrznych’ (2).
You can add an already existing simulation script with ‘Wybierz skrypt’ (3) or create a new one ‘Generuj nowy skrypt’ (4)