I'm testing a registration system which involves a sender sending a daily update file to be processed to update the database systems. In this file there is a date field, and if populated, the date field for a particular record will change and the system will change the previous record's date to be the updated date - 1 calendar day. So if the updated file has a date of 31/3/14, the previous record will have a date of 30/3/14.
So how would I be able to test this properly apart from the obvious? The only one I can think of is around the beginning/end of year, so for eg, if the update file contained a date of 1/1/14, then the system should update the date of the previous record to 31/12/13.