3 files changed, 48 insertions, 29 deletions

diff --git a/src/mailman/rules/docs/moderation.rst b/src/mailman/rules/docs/moderation.rst
index 56602189b..d1cc5fd67 100644
--- a/src/mailman/rules/docs/moderation.rst
+++ b/src/mailman/rules/docs/moderation.rst
@@ -3,9 +3,9 @@ Moderation
 ==========
 
 All members and nonmembers have a moderation action, which defaults to the
-list's default action.  When the action is not `defer`, the `moderation` rule
-flags the message as needing moderation.  This might be to automatically
-accept, discard, reject, or hold the message.
+appropriate list's default action.  When the action is not `defer`, the
+`moderation` rule flags the message as needing moderation.  This might be to
+automatically accept, discard, reject, or hold the message.
 
 Two separate rules check for member and nonmember moderation.  Member
 moderation happens early in the built-in chain, while nonmember moderation
@@ -22,15 +22,19 @@ Member moderation
     member-moderation
 
 Anne, a mailing list member, sends a message to the mailing list.  Her
-postings are not moderated.
-::
+moderation action is not set.
 
     >>> from mailman.testing.helpers import subscribe
-    >>> subscribe(mlist, 'Anne')
+    >>> member = subscribe(mlist, 'Anne')
+    >>> member
     <Member: Anne Person <aperson@example.com> on test@example.com
              as MemberRole.member>
+    >>> print(member.moderation_action)
+    None
+
+Because the list's default member action is set to `defer`, Anne's posting is
+not moderated.
 
-    >>> member = mlist.members.get_member('aperson@example.com')
     >>> print(mlist.default_member_action)
     Action.defer
 
@@ -46,8 +50,9 @@ Because Anne is not moderated, the member moderation rule does not match.
     False
 
 Once the member's moderation action is set to something other than `defer` or
-``None``, the rule matches.  Also, the message metadata has a few extra pieces
-of information for the eventual moderation chain.
+``None`` (given the list's current default member moderation action), the rule
+matches.  Also, the message metadata has a few extra pieces of information for
+the eventual moderation chain.
 
     >>> from mailman.interfaces.action import Action
     >>> member.moderation_action = Action.hold
@@ -71,20 +76,26 @@ postings are held for moderator approval.
     nonmember-moderation
 
 Bart, who is not a member of the mailing list, sends a message to the list.
-::
+He has no explicit nonmember moderation action.
 
     >>> from mailman.interfaces.member import MemberRole
-    >>> subscribe(mlist, 'Bart', MemberRole.nonmember)
+    >>> nonmember = subscribe(mlist, 'Bart', MemberRole.nonmember)
+    >>> nonmember
     <Member: Bart Person <bperson@example.com> on test@example.com
              as MemberRole.nonmember>
+    >>> print(nonmember.moderation_action)
+    None
+
+The list's default nonmember moderation action is to hold postings by
+nonmembers.
 
-    >>> nonmember = mlist.nonmembers.get_member('bperson@example.com')
     >>> print(mlist.default_nonmember_action)
     Action.hold
 
-When Bart is registered as a nonmember of the list, his moderation action is
-set to hold by default.  Thus the rule matches and the message metadata again
-carries some useful information.
+Since Bart is registered as a nonmember of the list, and his moderation action
+is set to None, the action falls back to the list's default nonmember
+moderation action, which is to hold the post for moderator approval.  Thus the
+rule matches and the message metadata again carries some useful information.
 
     >>> nonmember_msg = message_from_string("""\
     ... From: bperson@example.com
diff --git a/src/mailman/rules/moderation.py b/src/mailman/rules/moderation.py
index 9c89cf0b2..d3dc07a8f 100644
--- a/src/mailman/rules/moderation.py
+++ b/src/mailman/rules/moderation.py
@@ -44,8 +44,9 @@ class MemberModeration:
             member = mlist.members.get_member(sender)
             if member is None:
                 return False
-            action = (member.moderation_action
-                      or mlist.default_member_action)
+            action = (mlist.default_member_action
+                      if member.moderation_action is None
+                      else member.moderation_action)
             if action is Action.defer:
                 # The regular moderation rules apply.
                 return False
@@ -114,8 +115,9 @@ class NonmemberModeration:
                         _record_action(msgdata, action, sender,
                                        reason.format(action))
                         return True
-            action = (nonmember.moderation_action
-                      or mlist.default_nonmember_action)
+            action = (mlist.default_nonmember_action
+                      if nonmember.moderation_action is None
+                      else nonmember.moderation_action)
             if action is Action.defer:
                 # The regular moderation rules apply.
                 return False
diff --git a/src/mailman/rules/tests/test_moderation.py b/src/mailman/rules/tests/test_moderation.py
index 3e80aeeb5..05bae5e1b 100644
--- a/src/mailman/rules/tests/test_moderation.py
+++ b/src/mailman/rules/tests/test_moderation.py
@@ -160,15 +160,19 @@ MIME-Version: 1.0
 
 A message body.
 """)
-        # First, the message should get held
+        # First, the message should get held.
         msgdata = {}
         result = rule.check(self._mlist, msg, msgdata)
         self.assertTrue(result)
-        self.assertEqual(msgdata.get('moderation_action'), 'hold')
-        # Then the list's default nonmember action is changed
+        self.assertEqual(msgdata['moderation_action'], 'hold')
+        # As a side-effect, Anne has been added as a nonmember with a
+        # moderation action that falls back to the list's default.
+        anne = self._mlist.nonmembers.get_member('anne@example.com')
+        self.assertIsNone(anne.moderation_action)
+        # Then the list's default nonmember action is changed.
         self._mlist.default_nonmember_action = Action.discard
-        msg.replace_header('Message-ID', '<ant2>')
-        # This time, the message should be discarded
+        msg.replace_header('Message-ID', '<bee>')
+        # This time, the message should be discarded.
         result = rule.check(self._mlist, msg, msgdata)
         self.assertTrue(result)
         self.assertEqual(msgdata.get('moderation_action'), 'discard')
@@ -178,7 +182,9 @@ A message body.
         self._mlist.default_member_action = Action.accept
         user_manager = getUtility(IUserManager)
         anne = user_manager.create_address('anne@example.com')
-        self._mlist.subscribe(anne, MemberRole.member)
+        member = self._mlist.subscribe(anne, MemberRole.member)
+        # Anne's moderation rule falls back to the list default.
+        self.assertIsNone(member.moderation_action)
         rule = moderation.MemberModeration()
         msg = mfs("""\
 From: anne@example.com
@@ -189,15 +195,15 @@ MIME-Version: 1.0
 
 A message body.
 """)
-        # First, the message should get held
+        # First, the message gets accepted.
         msgdata = {}
         result = rule.check(self._mlist, msg, msgdata)
         self.assertTrue(result)
         self.assertEqual(msgdata.get('moderation_action'), 'accept')
-        # Then the list's default nonmember action is changed
+        # Then the list's default member action is changed.
         self._mlist.default_member_action = Action.hold
-        msg.replace_header('Message-ID', '<ant2>')
-        # This time, the message should be discarded
+        msg.replace_header('Message-ID', '<bee>')
+        # This time, the message is held.
         result = rule.check(self._mlist, msg, msgdata)
         self.assertTrue(result)
         self.assertEqual(msgdata.get('moderation_action'), 'hold')