Use doctest to execute examples in the docstring

📚 Documentation

Example snippets are inserted into the docstring to show usage. However, these pieces of code might be deprecated, or might not work. The module doctest aims to execute the tests written in docstring and it works fine with sphinx. It could help to detect earlier doc issues and provide a better doc.

Useful links

• https://docs.python.org/3/library/doctest.html
• https://www.sphinx-doc.org/en/master/usage/extensions/doctest.html

Note that some tests was written according to doctest https://github.com/pytorch/ignite/blob/b3d9849c2243be6068a64b5d1cf9c0ede727a2ea/ignite/handlers/timing.py#L30

The main point is the refactoring of every test to pass the validation. It means have consistent pieces of code (define training fn, engines, etc.) to provide reproducible examples.

[sdesrozis]

It’s done !

[vfdev-5]

@sdesrozis can we close this issue as solved or still there is something to be done ?