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Decide what should we do with doctests in CI #111704

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@sobolevn

Bug report

Initial PR and discussion: #111682

So, here's the problem:

Example 1::

>>> 1 + 2
3

Example 2:

.. doctest::

>>> 1 + 2
3

We have two tools: doctest (builtin module) and sphinx (3rd party) that can run these samples as doctests. The problem is that they define "doctest" term differently:

  • doctest module says that both of these examples are doctests
  • sphinx says that only example with .. doctest:: directive is a doctest

This is problematic, because not all example are actually executed in CI, right now we have a CI job that uses Sphinx. So, in the result of this we have broken doctest (1st meaning) examples in the docs.

Examples:

What can we do?

Options:

  1. Add .. doctest:: directives everywhere, but I think it is too much work and people will forget to do this
  2. Try to use doctest_test_doctest_blocks, see docs https://www.sphinx-doc.org/en/master/usage/extensions/doctest.html This is what I plan to do locally and I will send a PR with the results. I fear that quite a lot of doctests might be broken
  3. Add doctests to test_* files using something like
def load_tests(loader, tests, pattern):
    tests.addTests(doctest.DocFileSuite(
        os.path.join(REPO_ROOT, 'Doc/library/LIBNAME.rst'),
        module_relative=False,
    ))
    return tests

The last option is also problematic, because right now we can only run doctests in CI, when PR only touches Doc/ folder, I am not sure that it will be easy with this setup.

CC @AlexWaygood @AA-Turner

Linked PRs

Activity

  1. added
    type-bugAn unexpected behavior, bug, or error
    testsTests in the Lib/test dir
    docsDocumentation in the Doc dir
    buildThe build process and cross-build
    on Nov 3, 2023
  2. self-assigned this
    on Nov 3, 2023
  3. changed the title [-]Decide what should we do with doctests[/-] [+]Decide what should we do with doctests in CI[/+] on Nov 3, 2023
  4. sobolevn commented on Nov 3, 2023

    @sobolevn
    MemberAuthor

    I hope that I will send the first PR today / tomorrow, but I am a bit sick :(

  5. AlexWaygood commented on Nov 3, 2023

    @AlexWaygood
    Member

    Option (2) is definitely attractive. Just two concerns from me:

    1. How long will this make the Doctest CI job? It already takes 10 minutes to run all CPython's doctests via Sphinx; I worry that this option could make it significantly slower, by dramatically increasing the number of doctests run in CI. This is hypothetical, though; I might be wrong!
    2. I agree with you that there'll probably be quite a few that fail at first. If we could figure out a way to tackle the errors incrementally, like what we've been doing with the Sphinx nitpicks, that would be ideal. Would it be possible to apply doctest_test_doctest_blocks only to certain files? (Cc. @AA-Turner again as the Sphinx expert here!)
  6. AlexWaygood commented on Nov 3, 2023

    @AlexWaygood
    Member

    Also, rest up and get well soon!

  7. hugovk commented on Nov 3, 2023

    @hugovk
    Member

    Option 4: Modify Sphinx to run both types?

    But I'm also concerned about the doctest taking longer. Of the three docs jobs, doctest is the longest at 10 minutes (= 3m setup/building + 7m doctest) compared to 2.5 minutes each for the other two:

    image

    Can we do them in parallel instead of sequential? Can the doctest module run them quicker?

  8. sobolevn commented on Nov 3, 2023

    @sobolevn
    MemberAuthor

    Modify Sphinx to run both types?

    This is option 2 :)

  9. added a commit that references this issue on Nov 4, 2023
  10. sobolevn commented on Nov 7, 2023

    @sobolevn
    MemberAuthor

    After working with make doctest for a while, here are my thoughts:

    1. It does not allow to even run a single file (or maybe I cannot find the docs about it). This causes a lot of problems when debugging tests
    2. It uses stuff that is fundamentally incompatible with -m doctest, like testsetup
    3. It is hard to clean things up after usage (see gh-111726: Explicitly close database connections in sqlite3 doctests #111730), because you have to separate cleanup from the test itself (to not show it to user):
    .. testcleanup::
    
       import os
       os.remove("tutorial.db")
    1. If you want to skip some file, you have to:

    I didn't like this tool at all.
    It might be useful for small projects, but not for big ones.

  11. AlexWaygood commented on Nov 7, 2023

    @AlexWaygood
    Member
    • Add :skipIf: TO ALL DOCTESTS in a file (see

    Can't you just not add .. doctest to the REPL snippets in the documentation that you don't want to be treated as doctests? (Though I know we'd need to change that if we were to switch to a system where sphinx automatically treated all REPL snippets as doctests, regardless of whether they have the .. doctest directive above them.)

  12. sobolevn commented on Nov 7, 2023

    @sobolevn
    MemberAuthor

    Can't you just not add .. doctest

    Turns out that the answer is "no".
    See #111735
    It is a bit of a mess.

  13. sobolevn commented on Jul 10, 2025

    @sobolevn
    MemberAuthor

    I propose adding more text files to doctests, we can start with important ones and move slowly to increase the coverage.

    There are two options:

    1. .. doctest:: directive in the file itself. This allows us to add only some parts of the file to the doctest. Like we do here:

      cpython/Doc/library/typing.rst

      Lines 1473 to 1481 in c176543

      .. doctest::
      >>> from typing import Annotated, get_type_hints
      >>> def func(x: Annotated[int, "metadata"]) -> None: pass
      ...
      >>> get_type_hints(func)
      {'x': <class 'int'>, 'return': <class 'NoneType'>}
      >>> get_type_hints(func, include_extras=True)
      {'x': typing.Annotated[int, 'metadata'], 'return': <class 'NoneType'>}
      This way we can also create test setups and teardowns
    2. Using def load_test in some related test file with passing filename to load. Like we do here:
      def load_tests(loader, tests, ignore):
      tests.addTests(doctest.DocTestSuite(enum))
      lib_tests = os.path.join(REPO_ROOT, 'Doc/library/enum.rst')
      if os.path.exists(lib_tests):
      tests.addTests(doctest.DocFileSuite(
      lib_tests,
      module_relative=False,
      optionflags=doctest.ELLIPSIS|doctest.NORMALIZE_WHITESPACE,
      ))
      howto_tests = os.path.join(REPO_ROOT, 'Doc/howto/enum.rst')
      if os.path.exists(howto_tests) and sys.float_repr_style == 'short':
      tests.addTests(doctest.DocFileSuite(
      howto_tests,
      module_relative=False,
      optionflags=doctest.ELLIPSIS|doctest.NORMALIZE_WHITESPACE,
      ))
      return tests

    Important things to keep in mind:

    • There are builds that do not have docs nearby
    • There are different float formatting options
    • There are different optional dependencies
    • There are different OSes
  14. added a commit that references this issue on Jul 10, 2025
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