The intent: a general-purpose framework to test a CLI project needing numerous input files, and where all tests are only small variations upon a set of base input files.

On the one side: a folder with the set of base input files.
On the other side: a folder with tests specification files.

In every spec file, a sequence of numerous tests are listed in the dedicated testing language. Chunks in spec files define the base input files to work with, the CLI command to run, the slight modifications to be patched against the setup, and the output expectations.

When run, every test gets a temporary folder with a copy of all the base input files, and successively applies the patches / run the command / compare actual vs. expected outputs to eventually gather all tests results.