Going to take a stab at this.

From what it looks like the docstrings from submodules don't actually get pulled in anywhere. Should I just deprecate the entire np.testing module, since it looks mostly nose based? Or is there some other way I should document submodules of np.testing?

The rendered documentation does included the public functions from that module. that.This issue is about deprecating only the np.testing.dec functions, not the whole module. With that, the module structure could be simplified (but that is a different issue).

Ah, I see. So put it on the individual functions then?

The original ask was just to add a blurb in the docstring of the module to discourage the use of these functions. Deprecation warnings will be noisy, since the warning will be emitted during test collection. If you want to add the deprecations, please follow the pattern of

# Numpy 1.21.0, 2020-12-20
warnings.warn("msg" DeprecationWarning, stacklevel=2)

and make sure tests pass cleanly. The relevant tests of the deprecated functions should move to numpy/core/tests/test_deprecations

Now that the decorators are deprected we need to update the docs at https://numpy.org/devdocs/reference/routines.testing.html#decorators to make this clear.

Closing as the warnings are visible now.