Ignore trailing whitespace in cell comparison

[Iain-S]

Issue
If you have trailing whitespace in a Jupyter notebook cell, nb-black won't format it. For example (note the newline):

a=1

 

I have tested it with newlines and spaces.

Fix
It happens because nbb_unformatted_code (which comes from self.shell.user_ns["_i" + str(cell_id)]) is stripped of whitespace (not sure why but it is out of our control). Therefore, we should strip whitespace from nbb_cells[i].get_text() before we compare it to nbb_unformatted_code.

[dnanhkhoa]

Hi @Iain-S , thank you for the PR

Actually I haven't tested this yet. Do you have any problem so far with your fix?

[Iain-S]

Hi @dnanhkhoa , I haven't noticed any issues thus far.

A minor problem is that if the user has started to add new blank lines after submission but before completion of the cell, those new lines will be deleted. I suspect that this will be only a minor annoyance but an alternative solution would be to work out why the self.shell.user_ns[] code is stripped of whitespace.