Issue #6195: fix doctest to no longer try to read 'source' data from
binary files.
diff --git a/Lib/test/test_doctest.py b/Lib/test/test_doctest.py
index 9a128fb..8dcc8a4 100644
--- a/Lib/test/test_doctest.py
+++ b/Lib/test/test_doctest.py
@@ -2288,6 +2288,17 @@
>>> doctest.master = None # Reset master.
"""
+def test_testmod(): r"""
+Tests for the testmod function. More might be useful, but for now we're just
+testing the case raised by Issue 6195, where trying to doctest a C module would
+fail with a UnicodeDecodeError because doctest tried to read the "source" lines
+out of the binary module.
+
+ >>> import unicodedata
+ >>> doctest.testmod(unicodedata)
+ TestResults(failed=0, attempted=0)
+"""
+
######################################################################
## Main
######################################################################