FEATURE: Builtin pytest magic

[pylang]

There has been some discussion at pytest-dev on adding some way to run pytest in notebooks.

One proposal has been to invoke a magic similar to %matplotlib at the start of the notebook. This would a override the normal assertion output for any cell with pytest's detailed output (see example here).

Can we have a %pytest implemented as one of the builtin magics in jupyter notebooks?

[chmp]

Maybe of interest: I wrote a small package ipytest, which allows to run tests defined inside notebooks.

[pylang]

@chmp You should be commended on a brilliant attempt at tackling this. This is the best option I see so far.

In your README, you identify a few issues that are not obvious to most people and require attention, particularly with clearing the notebook globals when running tests. In the future, I hope there will be more dialog between the jupyter and pytest teams on making a idiomatic solution. Preferably, all the required boilerplate would be:

import pytest

%pytest

I am a bit hesitant to pepper additional magic throughout my notebooks to run tests. It is the only reason I still use nose. ))

[chmp]

@pylang Thanks a lot for the feedback. I understand your comment to have two parts:

• "global state handling is sup-optimal": I feel this issue is deeply tied to the notebook model and I don't see a simple way out. Deleting all old tests worked for me so far.
• "assertion rewriting via magics is cumbersome": I fully agree. The newest ipytest version (0.4.0b1) does not longer require magics to rewrite asserts.

Since I do not want to highjack the notebook issue tracker for ipytest issues, I collected my comments here. Feel free to comment and re-open the issue in case the changes do not work for you.