#14649: clarify DocTestSuite error when there are no docstrings.
Also adds tests to verify the documented behavior (which is probably a bug, as
indicated in the added comments).
Patch by Chris Jerdonek.
diff --git a/Doc/library/doctest.rst b/Doc/library/doctest.rst
index b6d1756..b07663c 100644
--- a/Doc/library/doctest.rst
+++ b/Doc/library/doctest.rst
@@ -1060,6 +1060,16 @@
.. versionchanged:: 2.5
The parameter *encoding* was added.
+ .. note::
+ Unlike :func:`testmod` and :class:`DocTestFinder`, this function raises
+ a :exc:`ValueError` if *module* contains no docstrings. You can prevent
+ this error by passing a :class:`DocTestFinder` instance as the
+ *test_finder* argument with its *exclude_empty* keyword argument set
+ to ``False``::
+
+ >>> finder = doctest.DocTestFinder(exclude_empty=False)
+ >>> suite = doctest.DocTestSuite(test_finder=finder)
+
.. function:: DocTestSuite([module][, globs][, extraglobs][, test_finder][, setUp][, tearDown][, checker])