currently file feeds (around 4 or 5 files) are happening from System A to System B via Secure File Transfer.
Both these systems belong to two different vendors and are geographically separated.
The existing file feeds will now also be sent to System C. There is no change expected to the current file feeds in terms of elements and fields. No additional file feeds are getting added. Please note that System - B and System - C both belong to same vendor.
Can you please suggest any test strategy for performing this tests to ensure that the file are transmitted correctly to the new System-c and
also to system-B asusual without any issues.
The obvious answer is to grab a copy of all files that were transfered then do a diff on them. Is that out of the question? If the files were posted as-is onto a web site, the diff could be run from a single location I believe.
In case if you can't access all the files from the same location, consider generating hash values of the files using md5 or similar method. There are many md5/crc calculators you can download.
When testing, create a text file with the hash values of all the files (probably you can transfer this file too with the others). Then you can generate hash values again in each site and compare to see if anything has changed.