Why should we install master? What made it suddenly fail?

@jnothman

Why should we install master?

We always install master/nightly builds in cron job? We install stable version in other jobs.

What made it suddenly fail?

#12819 adds an example.

IMO pillow should not be a mandatory dependency for doctests. Is there a way to conditionally skip doctests ?

IMO pillow should not be a mandatory dependency for doctests. Is there a way to conditionally skip doctests ?

Some tests also rely on pillow, installing pillow in cron job will help us discover possible bugs earlier.

Hmm, also I don't understand how CI passed in #12819 if pillow was missing and it added an example that required it...

I don't understand how CI passed in #12819 if pillow was missing and it added an example that required it...

Nevermind, I see it's installed in all CI.

Some tests also rely on pillow

Agreed, my point is that checking if pillow is installed and then running those tests sounds fine. Having some test fail if pillow is not installed is IMO not great. I mean a mandatory test dependency is not as bad as a runtime dependency, but it also comes with some of the same constraints and costs.

Also, for instance, we are not requiring pandas for tests (which is an incresingly important part of our API tests) so I'm not sure why should we should require pillow that is only used in a few marginal tests.

Depends what others think about this, but I would be +1 to merge this, but then not install pillow in one of the other Travis CI jobs (in some other PR).

I guess there's consensus to merge?