Y'know, I think you might be thinking too hard about this one. A test script is a test script. There are prerequisites that need to be in place prior to executing the test...there are steps that need to be completed to perform the test...and there are steps that need to be done at the end to clean things up.
And while it may have come across a little snarky above, it really is similar to a high-level test case. About the only difference between it and what I would do is that there would be a little more detail in regards to what data needs to be set up and where it needs to be set up...which batch I would need to run (pointers to the script to be executed)...and which tables I need to validate the end results in (along with some queries that will make the life of the tester a little easier.)
From my distant past, here is (from memory) a relatively simple batch test.
1. Identify (or setup) payment transactions in the payment table such that they would be sent to the biller tomorrow.
2. Run the ACH batch. (This generates the file that would be sent to ACH.)
3. Validate that the records identified in step 1 are included in the outbound file.
If you wanted to reverse the process (i.e., a load), then you would want to do something along the lines of the following:
1. Create/modify ACH response file (to fulfill whatever requirements you wanted to validate)
2. Run the ACH response file batch
3. Validate that the records included in step 1 are updated as expected in the database.
(There is a lot of detail that could be filled in here to make these mini-scripts more robust. But, depending on the tester and the requirements, there may not be a need for more of detail.)