From Longman Dictionary of Contemporary Englishdummy runˌdummy ˈrun noun [countable] PRACTISE/PRACTICEan occasion when you practise doing something in complete detail to see if it works SYN dry run Do a dummy run to see how long it will take.
Examples from the Corpus
dummy run• Maybe everyone was out in force as a dummy run for the Countryside march on 18 March.• In a recent dummy run, the 4th Marine Brigade stormed a beach on Catalina Island. 