Use overwrite_file context manager in test_ext_autodoc_configs

[marxin]

The tests modify source files (index.rst), that is not restored and thus another test can reach a modified source file and it leads to unexpected test results.

Related: #11285

@AA-Turner

[marxin]

Looking at:

sphinx/tests/test_docutilsconf.py

Lines 21 to 22 in 188b869

	docutilsconf=('[restructuredtext parser]\n'
	'trim_footnote_reference_space: true\n'))

there's a similar problem that docutils.conf is modified in srcdir:

sphinx/sphinx/testing/util.py

Lines 115 to 116 in 188b869

	if docutilsconf is not None:
	(srcdir / 'docutils.conf').write_text(docutilsconf)

and it's not restored later. Thus, we might want to use overwrite_file here. What do you think?

[AA-Turner]

Perhaps if docutilsconf is set we could also clean it up in SphinxTestApp.cleanup()?

A

[AA-Turner]

Thanks!

[marxin]

Perhaps if docutilsconf is set we could also clean it up in SphinxTestApp.cleanup()?

Sure, done in #11345.