False flags errors from `nbqa isort`

When running nbqa isort on some notebooks which have already been fixed up previously with nbqa isort, false flag errors are being raised. Take a look at the terminal output below. I have a notebook, examples/custom-nodes.ipynb, which does not contain any isort formatting issues, as it was alrady run through nbqa isort. Running nbqa isort with --check-only indicates an error. Running nbqa isort again indicates that changes were made to the file. Running git diff shows that no changes were infact made. Running nbqa isort with --check-only again still reports that there are errors in the file.

$ nbqa isort --check-only examples/custom-nodes.ipynb 
ERROR: /made/up/path/to/examples/custom-nodes.ipynb Imports are incorrectly sorted and/or formatted.
$ nbqa isort examples/custom-nodes.ipynb 
Fixing /made/up/path/to/examples/custom-nodes.ipynb
$ git diff examples/custom-nodes.ipynb
$ nbqa isort --check-only examples/custom-nodes.ipynb 
ERROR: /made/up/path/to/examples/custom-nodes.ipynb Imports are incorrectly sorted and/or formatted.

[MarcoGorelli]

Sure, tomorrow I’ll post some outputs as I step through the code

Another solution could be to change the return code of nbqa-diff to be 1 if the tool would have modified the notebook and 0 otherwise. Then you could use that in CI in place of isort’s check-only

[MarcoGorelli]

Fixed in version 1.3.0 🚀