2 files changed, 60 insertions, 1 deletions
diff --git a/src/mailman/rules/no_subject.py b/src/mailman/rules/no_subject.py
index 4b53067a5..e6a3be6ed 100644
--- a/src/mailman/rules/no_subject.py
+++ b/src/mailman/rules/no_subject.py
@@ -34,5 +34,7 @@ class NoSubject:
 
     def check(self, mlist, msg, msgdata):
         """See `IRule`."""
-        subject = msg.get('subject', '').strip()
+        # Convert the header value to string because it may be an
+        # email.header.Header instance.
+        subject = str(msg.get('subject', '')).strip()
         return subject == ''
diff --git a/src/mailman/rules/tests/test_no_subject.py b/src/mailman/rules/tests/test_no_subject.py
new file mode 100644
index 000000000..1647f96d5
--- /dev/null
+++ b/src/mailman/rules/tests/test_no_subject.py
@@ -0,0 +1,57 @@
+# Copyright (C) 2015 by the Free Software Foundation, Inc.
+#
+# This file is part of GNU Mailman.
+#
+# GNU Mailman is free software: you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free
+# Software Foundation, either version 3 of the License, or (at your option)
+# any later version.
+#
+# GNU Mailman is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# GNU Mailman.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Test the `no_subject` header rule."""
+
+__all__ = [
+    'TestNoSubject',
+    ]
+
+
+import os
+import unittest
+from email.header import Header
+
+from mailman.app.lifecycle import create_list
+from mailman.email.message import Message
+from mailman.rules import no_subject
+from mailman.testing.layers import ConfigLayer
+
+
+
+class TestNoSubject(unittest.TestCase):
+    """Test the no_subject rule."""
+
+    layer = ConfigLayer
+
+    def setUp(self):
+        self._mlist = create_list('test@example.com')
+        self._rule = no_subject.NoSubject()
+
+    def test_header_instance_empty(self):
+        # Check the case where the subject is a Header instance
+        msg = Message()
+        msg["Subject"] = Header("")
+        result = self._rule.check(self._mlist, msg, {})
+        self.assertTrue(result)
+
+    def test_header_instance_not_empty(self):
+        # Check the case where the subject is a Header instance
+        msg = Message()
+        msg["Subject"] = Header("Test subject")
+        result = self._rule.check(self._mlist, msg, {})
+        self.assertFalse(result)