[New-bugs-announce] [issue43681] doctest forgets previous imports

[Ethan Furman]

New submission from Ethan Furman <ethan at stoneleaf.us>:

In the Python 3.10 Doc/library/enum.rst file was the following:

.. class:: FlagBoundary

   *FlagBoundary* controls how out-of-range values are handled in *Flag* and its
   subclasses.

   .. attribute:: STRICT

      Out-of-range values cause a :exc:`ValueError` to be raised.  This is the
      default for :class:`Flag`::

         >>> from enum import STRICT
         >>> class StrictFlag(Flag, boundary=STRICT):
         ...     RED = auto()
         ...     GREEN = auto()
         ...     BLUE = auto()
         >>> StrictFlag(2**2 + 2**4)
         Traceback (most recent call last):
         ...
         ValueError: StrictFlag: invalid value: 20
             given 0b0 10100
           allowed 0b0 00111

   .. attribute:: CONFORM

      Out-of-range values have invalid values removed, leaving a valid *Flag*
      value::

         >>> from enum import CONFORM
         >>> class ConformFlag(Flag, boundary=CONFORM):
         ...     RED = auto()
         ...     GREEN = auto()
         ...     BLUE = auto()
         >>> ConformFlag(2**2 + 2**4)
         ConformFlag.BLUE

   .. attribute:: EJECT

      Out-of-range values lose their *Flag* membership and revert to :class:`int`.
      This is the default for :class:`IntFlag`::

         >>> from enum import EJECT
         >>> class EjectFlag(Flag, boundary=EJECT):
         ...     RED = auto()
         ...     GREEN = auto()
         ...     BLUE = auto()
         >>> EjectFlag(2**2 + 2**4)
         20

   .. attribute:: KEEP

      Out-of-range values are kept, and the *Flag* membership is kept.  This is
      used for some stdlib flags:

         >>> from enum import KEEP
         >>> class KeepFlag(Flag, boundary=KEEP):
         ...     RED = auto()
         ...     GREEN = auto()
         ...     BLUE = auto()
         >>> KeepFlag(2**2 + 2**4)
         KeepFlag.BLUE|0x10


All four tests are relying on a previous `from enum import Flag`, but only the three tests pass -- the fourth raises:

    Traceback (most recent call last):
      File "/home/runner/work/cpython/cpython/Lib/doctest.py", line 1337, in __run
        exec(compile(example.source, filename, "single",
      File "<doctest default[1]>", line 1, in <module>
        class KeepFlag(Flag, boundary=KEEP):
    NameError: name 'Flag' is not defined

----------
components: Library (Lib)
messages: 389903
nosy: ethan.furman
priority: normal
severity: normal
stage: test needed
status: open
title: doctest forgets previous imports
type: behavior
versions: Python 3.10

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue43681>
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