Consider adding `doctest.skip_if` decorator about cpython

[serhiy-storchaka]

There is a problem with applying this to non-test functions. We do not want to replace docstrings of library functions if doctests are skipped.

Also, what is the solution for conditional skipping of module-level doctests?

[sobolevn]

Or instead of patching the string, we can go with .__doctest_skip__ attribute for a function.

[sobolevn]

There is a problem with applying this to non-test functions. We do not want to replace docstrings of library functions if doctests are skipped.

Hm, indeed. This might be a bit more complex: we can add # doctest: +SKIP to all >>> lines dynamically.

Does not seem too hard, but it will be harder for sure.

Also, what is the solution for conditional skipping of module-level doctests?

This can be adjusted to include doctest.skip_if(condition, module=True).

[serhiy-storchaka]

This was my idea too. I thought about making it more general and also setting other options for the whole test, but I don't see a use case for other options for now.

Alternative ideas:

• Introduce a special exception doctest.SkipTest, so that raising it will skip all following examples.
• Introduce a syntax for conditional skipping, e.g. +SKIP if varname. It is enough to support only simple variable names, not complex expressions. It would be nice to also add syntax to apply options to all subsequent examples instead of just one example.

They are more complex changes of doctest machinery.