subroutine modification and testing

I'm trying to modify one of the subroutines that is used to decipher a particular type of csv file out of an entire project of vba macro subroutines. I may be a bit vague here, but I'm not too sure how to test my modified subroutine while keeping the rest of the project's codes relatively intact as the code that I'm working on involves instantiating a class object defined in the original class module code in the project. Should I be coding the subroutine that reads the csv file independently on a separate excel workbook macro?

Hello Stanigator,

That's a good strategy. Isolate and build the code to read the CSV file first. Once you know this works correctly, you can move on to the next step of integration. Isolate and test each part if you can. Makes troubleshooting much easier.

Sincerely,
Leith Ross