Add Notebooks Validation

[danielfeismann]

We use notebooks for documentation and other useful purposes. Testing / check if they are still valid would be very good.

This may can be done by nbval

• check if and how this can be done
• implement it for the existing notebooks

[sebastian-peter]

Interesting, was not aware of nbval. So what this would do is checking whether the developer has at least run the whole notebook (thus creating the right outputs which will be validated against), at which point he would've noticed any errors, right?

[danielfeismann]

I haven't checked this in detail, but my understanding is that it reruns the notebooks and can check the outputs against expected ones. Thus, one could notice that the changes affected the outputs within the docs.

[sebastian-peter]

Right, and the expected outputs are just whatever calculation output has been stored with the notebook beforehand. So effectively, in my opinion, we'd check that the developer has actually run the whole notebook before committing. Which does make sense to me though, because if one doesn't, there might easily be some errors in execution that one would miss.