#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 cdd6c26..cad03bd 100644
--- a/Doc/library/doctest.rst
+++ b/Doc/library/doctest.rst
@@ -1024,6 +1024,16 @@
This function uses the same search technique as :func:`testmod`.
+ .. 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)
+
Under the covers, :func:`DocTestSuite` creates a :class:`unittest.TestSuite` out
of :class:`doctest.DocTestCase` instances, and :class:`DocTestCase` is a