COMPAT: numpy test warning

[nschloe]

I'm currently testing a numpy deprecation to assess its impact on the ecosystem (numpy/numpy#10615). To this end, I'd like to run pandas tests with -Werror. Doing that, I see that pandas throws a bunch of warnings at other places. Are those intentional? Perhaps pandas should test warning-free out of the box.

[TomAugspurger]

We raise on warnings from NumPy in our numpydev build, which uses the environment from ci/deps/azure-37-numpydev.yaml.

I'm not sure how feasible it would be to fail on warnings for all our builds, given the number of optional dependencies we have.

[TomAugspurger]

That's configured at https://github.com/pandas-dev/pandas/blob/master/ci/azure/posix.yml#L47-L53.

[jbrockmendel]

I'm not sure how feasible it would be to fail on warnings for all our builds, given the number of optional dependencies we have.

This would fail in a bunch of places we don't have control over. The biggest one is imports from collections that need to be updated to import from collections.abc. We could try silencing those in the pytest config and see if whats left is manageable.

[nschloe]

I'm playing around with it atm and will submit a PR shortly. We can look at the diff then.