First, I would create a Boolean Argument in your Main xaml for ‘TestMode’, so you can easily set that to True or False in Studio or Orchestrator (after it’s deployed).
Then, use that Boolean in your code to set your input and output filepath locations, which would be read in from your config xlsx. So, IF True then assign test filepaths, else assign prod filepaths. You can also assign it in the dictionary.
IF activity condition: in_TestMode
Assign config("TestMode") = True
Assign config("Input_FilePath") = config("Input_FilePath_Test").ToString
Assign config("Output_FilePath") = config("Output_FilePath_Test").ToString
Assign config("Portal_URL") = config("Portal_URL_Test").ToString
Assign config("TestMode") = False
(although using Library projects, the URL would likely be integrated in the Library package and therefore a test argument would need to be implemented in its own arguments)
You can also set other variables based on the Boolean argument if needed.
Finally, place copies of data if needed in the Test location.
You can also use Assets if it’s something shared between multiple projects.
This is just an idea, but hope it helps.