pytest_doctest_docutils(fix[collect]): Backport autouse fixtures support

Backport: pytest commit 9cd14b4ff (2024-02-06)
Ref: pytest-dev/pytest@9cd14b4ff

why: Autouse fixtures were not being discovered for doctest files
what:
- Add parsefactories() call to DocTestDocutilsFile.collect()
- Ensures session fixture manager processes the doctest module
- Allows autouse fixtures from conftest.py to apply to doctests

Author: tony

src/pytest_doctest_docutils.py

@@ -306,6 +306,12 @@ def collect(self) -> Iterable[DoctestItem]:
         # Uses internal doctest module parsing mechanism.
         finder = DocutilsDocTestFinder()
 
+        # While doctests in .rst/.md files don't support fixtures directly,
+        # we still need to pick up autouse fixtures.
+        # Backported from pytest commit 9cd14b4ff (2024-02-06).
+        # https://github.com/pytest-dev/pytest/commit/9cd14b4ff
+        self.session._fixturemanager.parsefactories(self)
+
         optionflags = get_optionflags(self.config)
 
         runner = _get_runner(