#310: support exception messages in the `testoutput blocks of the doctest` extension.

Also add minimal test cases for the doctest extension.

tests/test_doctest.py

@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+"""
+    test_doctest
+    ~~~~~~~~~~~~
+
+    Test the doctest extension.
+
+    :copyright: Copyright 2007-2010 by the Sphinx team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+import sys
+import StringIO
+
+from util import *
+
+status = StringIO.StringIO()
+
+@with_app(buildername='doctest', status=status)
+def test_build(app):
+    app.builder.build_all()
+    if app.statuscode != 0:
+        print >>sys.stderr, status.getvalue()
+        assert False, 'failures in doctests'