Provide some guidance on specifying test dependencies

[nchammas]

The packaging guide could use a brief blurb providing guidance on how to specify test dependencies for your project.

Some background:

• There is this question on Stack Overflow on how to use the tests_require option of setuptools.setup(). The question has 25K views.
• The setuptools docs for tests_require explain that the option is used for the test command, but also that the test command was deprecated in version 41.5.0.

Would it make sense to add something to the setuptools guide on specifying test dependencies, and specifically on whether or not to use tests_require?

What would the guidance be?

[smheidrich]

I agree that this should be covered.

AFAIK the current "recommended way" of doing this in setuptools is to add an optional dependency ("extra") for it, named something like tests or test.

[abravalheri]

Hi @smheidrich I think testing is also common, it is used in setuptools itself and I also think in virtualenv.

testing might have became popular because it is one of the examples in the tox docs.