Allow fall backs for moderation actions.

The `moderation_action` for members and nonmember can now be ``None``
which signals falling back to the appropriate list default action,
e.g. `default_member_action` and `default_nonmember_action`.  Given by
Aurélien Bompard.

Closes #189

1 files changed, 26 insertions, 15 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