Optional import hypotheses doesn't install hypothesis

[rmetcalfe-msp]

Location of the documentation

https://pandera.readthedocs.io/en/stable/data_synthesis_strategies.html#usage-in-unit-tests
https://pandera.readthedocs.io/en/stable/index.html#extras

Documentation problem

When reading about how to create example dataframes from schemas on this page it mentions that you need hypothesis library.
Skipping to the index page/README to understand if that's an optional dependency seems to indicate it is, though there's some confusion over spelling hypothesis vs hypotheses.

This lead me to get ModuleNotFoundError: No module named 'hypothesis' errors until I dug further and discovered that
calling pip install pandera[hypotheses] only actually installs scipy, and you have to install pandera[strategies] to get hypothesis.

Suggested fix for documentation

I would suggest including hypothesis library with the pandera[hypotheses] optional install and fixing the discrepancy in spelling, or specifying in the strategy page that you need to install pandera[strategies] for this functionality.

[cosmicBboy]

This is an unfortunate naming collision.

When I added Hypothesis checks to the codebase I didn't anticipate ever using the hypothesis library for data synthesis.

pip install pandera[hypotheses] unlocks hypothesis checks.

pip install pandera[strategies] unlocks data synthesis strategies, which uses hypothesis.

To clarify this it would make sense to add the appropriate pip install commands in the corresponding pages:

• https://pandera.readthedocs.io/en/stable/data_synthesis_strategies.html#usage-in-unit-tests: pip install pandera[strategies]
• https://pandera.readthedocs.io/en/stable/hypothesis.html: pip install pandera[hypotheses]

Would you be able to make a PR for the docs updates?

[cosmicBboy]

@rmetcalfe-msp any thoughts on the docs solution to clarify this behavior?

[rmetcalfe-msp]

@cosmicBboy thanks for the explanation, sounds reasonable.
I'll try address in a PR when I have some time.