25 files changed, 162 insertions, 389 deletions

diff --git a/src/mailman/runners/archive.py b/src/mailman/runners/archive.py
index 240d991f6..cfa0b1a12 100644
--- a/src/mailman/runners/archive.py
+++ b/src/mailman/runners/archive.py
@@ -17,17 +17,13 @@
 
 """Archive runner."""
 
-__all__ = [
-    'ArchiveRunner',
-    ]
-
-
 import copy
 import logging
 
 from email.utils import parsedate_tz, mktime_tz
 from datetime import datetime
 from lazr.config import as_timedelta
+from mailman import public
 from mailman.config import config
 from mailman.core.runner import Runner
 from mailman.interfaces.archiver import ClobberDate
@@ -38,7 +34,6 @@ from mailman.interfaces.mailinglist import IListArchiverSet
 log = logging.getLogger('mailman.archiver')
 
 
-
 def _should_clobber(msg, msgdata, archiver):
     """Should the Date header in the original message get clobbered?"""
     # Calculate the Date header of the message as a datetime.  What if there
@@ -49,12 +44,12 @@ def _should_clobber(msg, msgdata, archiver):
         return True
     section = getattr(config.archiver, archiver, None)
     if section is None:
-        log.error('No archiver config section found: {0}'.format(archiver))
+        log.error('No archiver config section found: {}'.format(archiver))
         return False
     try:
         clobber = ClobberDate[section.clobber_date]
     except ValueError:
-        log.error('Invalid clobber_date for "{0}": {1}'.format(
+        log.error('Invalid clobber_date for "{}": {}'.format(
             archiver, section.clobber_date))
         return False
     if clobber is ClobberDate.always:
@@ -81,7 +76,7 @@ def _should_clobber(msg, msgdata, archiver):
     return (abs(now() - claimed_date) > skew)
 
 
-
+@public
 class ArchiveRunner(Runner):
     """The archive runner."""
 
diff --git a/src/mailman/runners/bounce.py b/src/mailman/runners/bounce.py
index ba05b400d..4150dc9b5 100644
--- a/src/mailman/runners/bounce.py
+++ b/src/mailman/runners/bounce.py
@@ -20,6 +20,7 @@
 import logging
 
 from flufl.bounce import all_failures, scan_message
+from mailman import public
 from mailman.app.bounces import ProbeVERP, StandardVERP, maybe_forward
 from mailman.core.runner import Runner
 from mailman.interfaces.bounce import BounceContext, IBounceProcessor
@@ -32,7 +33,7 @@ log = logging.getLogger('mailman.bounce')
 elog = logging.getLogger('mailman.error')
 
 
-
+@public
 class BounceRunner(Runner):
     """The bounce runner."""
 
@@ -79,7 +80,7 @@ class BounceRunner(Runner):
                         address = address.decode('utf-8')
                     except UnicodeError:
                         log.exception('Ignoring non-UTF-8 encoded '
-                                      'address: {0}'.format(address))
+                                      'address: {}'.format(address))
                         continue
                 self._processor.register(mlist, address, msg, context)
         else:
diff --git a/src/mailman/runners/command.py b/src/mailman/runners/command.py
index 59d437469..15ccca438 100644
--- a/src/mailman/runners/command.py
+++ b/src/mailman/runners/command.py
@@ -17,11 +17,6 @@
 
 """-request robot command runner."""
 
-__all__ = [
-    'CommandRunner',
-    'Results',
-    ]
-
 # See the delivery diagram in IncomingRunner.py.  This module handles all
 # email destined for mylist-request, -join, and -leave.  It no longer handles
 # bounce messages (i.e. -admin or -bounces), nor does it handle mail to
@@ -34,6 +29,7 @@ from email.errors import HeaderParseError
 from email.header import decode_header, make_header
 from email.iterators import typed_subpart_iterator
 from io import StringIO
+from mailman import public
 from mailman.config import config
 from mailman.core.i18n import _
 from mailman.core.runner import Runner
@@ -48,7 +44,6 @@ NL = '\n'
 log = logging.getLogger('mailman.vette')
 
 
-
 class CommandFinder:
     """Generate commands from the content of a message."""
 
@@ -120,7 +115,7 @@ class CommandFinder:
             yield parts
 
 
-
+@public
 @implementer(IEmailResults)
 class Results:
     """The email command results."""
@@ -143,7 +138,7 @@ The results of your email command are provided below.
         return value
 
 
-
+@public
 class CommandRunner(Runner):
     """The email command runner."""
 
@@ -173,9 +168,9 @@ class CommandRunner(Runner):
         # Include just a few key pieces of information from the original: the
         # sender, date, and message id.
         print(_('- Original message details:'), file=results)
-        subject = msg.get('subject', 'n/a')
-        date = msg.get('date', 'n/a')
-        from_ = msg.get('from', 'n/a')
+        subject = msg.get('subject', 'n/a')         # flake8: noqa
+        date = msg.get('date', 'n/a')               # flake8: noqa
+        from_ = msg.get('from', 'n/a')              # flake8: noqa
         print(_('    From: $from_'), file=results)
         print(_('    Subject: $subject'), file=results)
         print(_('    Date: $date'), file=results)
diff --git a/src/mailman/runners/digest.py b/src/mailman/runners/digest.py
index 3d540d73f..f35b42b9a 100644
--- a/src/mailman/runners/digest.py
+++ b/src/mailman/runners/digest.py
@@ -17,11 +17,6 @@
 
 """Digest runner."""
 
-__all__ = [
-    'DigestRunner',
-    ]
-
-
 import re
 import logging
 
@@ -31,6 +26,7 @@ from email.mime.message import MIMEMessage
 from email.mime.text import MIMEText
 from email.utils import formatdate, getaddresses, make_msgid
 from io import StringIO
+from mailman import public
 from mailman.config import config
 from mailman.core.i18n import _
 from mailman.core.runner import Runner
@@ -46,7 +42,6 @@ from urllib.error import URLError
 log = logging.getLogger('mailman.error')
 
 
-
 class Digester:
     """Base digester class."""
 
@@ -85,7 +80,7 @@ class Digester:
                 self._header = decorate(mlist, mlist.digest_header_uri)
             except URLError:
                 log.exception(
-                    'Digest header decorator URI not found ({0}): {1}'.format(
+                    'Digest header decorator URI not found ({}): {}'.format(
                         mlist.fqdn_listname, mlist.digest_header_uri))
                 self._header = ''
         self._toc = StringIO()
@@ -110,8 +105,8 @@ class Digester:
             if not username:
                 username = addresses[0][1]
         if username:
-            username = ' ({0})'.format(username)
-        lines = wrap('{0:2}. {1}'. format(count, subject), 65).split('\n')
+            username = ' ({})'.format(username)
+        lines = wrap('{:2}. {}'. format(count, subject), 65).split('\n')
         # See if the user's name can fit on the last line
         if len(lines[-1]) + len(username) > 70:
             lines.append(username)
@@ -145,8 +140,6 @@ class Digester:
         msg['Message'] = count.decode('utf-8')
 
 
-
-
 class MIMEDigester(Digester):
     """A MIME digester."""
 
@@ -176,7 +169,8 @@ class MIMEDigester(Digester):
                                 _charset=self._charset)
         except UnicodeError:
             toc_part = MIMEText(toc_text.encode('utf-8'), _charset='utf-8')
-        toc_part['Content-Description']= _("Today's Topics ($count messages)")
+        toc_part['Content-Description'] = _(
+            "Today's Topics ($count messages)")
         self._message.attach(toc_part)
 
     def add_message(self, msg, count):
@@ -210,7 +204,6 @@ class MIMEDigester(Digester):
         return self._message
 
 
-
 class RFC1153Digester(Digester):
     """A digester of the format specified by RFC 1153."""
 
@@ -247,7 +240,7 @@ class RFC1153Digester(Digester):
         for header in config.digests.plain_digest_keep_headers.split():
             if header in msg:
                 value = oneline(msg[header], in_unicode=True)
-                value = wrap('{0}: {1}'.format(header, value))
+                value = wrap('{}: {}'.format(header, value))
                 value = '\n\t'.join(value.split('\n'))
                 print(value, file=self._text)
         print(file=self._text)
@@ -277,7 +270,7 @@ class RFC1153Digester(Digester):
                     self._mlist, self._mlist.digest_footer_uri)
             except URLError:
                 log.exception(
-                    'Digest footer decorator URI not found ({0}): {1}'.format(
+                    'Digest footer decorator URI not found ({}): {}'.format(
                         self._mlist.fqdn_listname,
                         self._mlist.digest_footer_uri))
                 footer_text = ''
@@ -307,7 +300,7 @@ class RFC1153Digester(Digester):
         return self._message
 
 
-
+@public
 class DigestRunner(Runner):
     """The digest runner."""
 
@@ -364,7 +357,7 @@ class DigestRunner(Runner):
                 mime_recipients.add(email_address)
             else:
                 raise AssertionError(
-                    'Digest member "{0}" unexpected delivery mode: {1}'.format(
+                    'Digest member "{}" unexpected delivery mode: {}'.format(
                         email_address, member.delivery_mode))
         # Add also the folks who are receiving one last digest.
         for address, delivery_mode in mlist.last_digest_recipients:
@@ -376,7 +369,7 @@ class DigestRunner(Runner):
                 mime_recipients.add(address.original_email)
             else:
                 raise AssertionError(
-                    'OLD recipient "{0}" unexpected delivery mode: {1}'.format(
+                    'OLD recipient "{}" unexpected delivery mode: {}'.format(
                         address, delivery_mode))
         # Send the digests to the virgin queue for final delivery.
         queue = config.switchboards['virgin']
diff --git a/src/mailman/runners/incoming.py b/src/mailman/runners/incoming.py
index 6d576cb50..dd9254194 100644
--- a/src/mailman/runners/incoming.py
+++ b/src/mailman/runners/incoming.py
@@ -26,11 +26,7 @@ prepared for delivery.  Rejections, discards, and holds are processed
 immediately.
 """
 
-__all__ = [
-    'IncomingRunner',
-    ]
-
-
+from mailman import public
 from mailman.core.chains import process
 from mailman.core.runner import Runner
 from mailman.database.transaction import transaction
@@ -39,7 +35,7 @@ from mailman.interfaces.usermanager import IUserManager
 from zope.component import getUtility
 
 
-
+@public
 class IncomingRunner(Runner):
     """The incoming runner."""
 
diff --git a/src/mailman/runners/lmtp.py b/src/mailman/runners/lmtp.py
index 3ec9e37c2..35cff4c94 100644
--- a/src/mailman/runners/lmtp.py
+++ b/src/mailman/runners/lmtp.py
@@ -34,17 +34,13 @@ so that the peer mail server can provide better diagnostics.
     http://www.faqs.org/rfcs/rfc2033.html
 """
 
-__all__ = [
-    'LMTPRunner',
-    ]
-
-
 import sys
 import email
 import logging
 import asyncore
 
 from email.utils import parseaddr
+from mailman import public
 from mailman.config import config
 from mailman.core.runner import Runner
 from mailman.database.transaction import transactional
@@ -94,8 +90,8 @@ SUBADDRESS_QUEUES = dict(
     request='command',
     )
 
-DASH    = '-'
-CRLF    = '\r\n'
+DASH = '-'
+CRLF = '\r\n'
 ERR_451 = '451 Requested action aborted: error in processing'
 ERR_501 = '501 Message has defects'
 ERR_502 = '502 Error: command HELO not implemented'
@@ -106,7 +102,6 @@ ERR_550_MID = '550 No Message-ID header provided'
 smtpd.__version__ = 'GNU Mailman LMTP runner 1.1'
 
 
-
 def split_recipient(address):
     """Split an address into listname, subaddress and domain parts.
 
@@ -134,7 +129,6 @@ def split_recipient(address):
     return listname, subaddress, domain
 
 
-
 class Channel(smtpd.SMTPChannel):
     """An LMTP channel."""
 
@@ -151,13 +145,12 @@ class Channel(smtpd.SMTPChannel):
         """HELO is not a valid LMTP command."""
         self.push(ERR_502)
 
-    ## def push(self, arg):
-    ##     import pdb; pdb.set_trace()
-    ##     return super().push(arg)
-
+    # def push(self, arg):
+    #     import pdb; pdb.set_trace()
+    #     return super().push(arg)
 
 
-
+@public
 class LMTPRunner(Runner, smtpd.SMTPServer):
     # Only __init__ is called on startup. Asyncore is responsible for later
     # connections from the MTA.  slice and numslices are ignored and are
diff --git a/src/mailman/runners/nntp.py b/src/mailman/runners/nntp.py
index 710f326b0..b125fe4f9 100644
--- a/src/mailman/runners/nntp.py
+++ b/src/mailman/runners/nntp.py
@@ -17,11 +17,6 @@
 
 """NNTP runner."""
 
-__all__ = [
-    'NNTPRunner',
-    ]
-
-
 import re
 import email
 import socket
@@ -29,6 +24,7 @@ import logging
 import nntplib
 
 from io import StringIO
+from mailman import public
 from mailman.config import config
 from mailman.core.runner import Runner
 from mailman.interfaces.nntp import NewsgroupModeration
@@ -53,7 +49,7 @@ mcre = re.compile(r"""
     """, re.VERBOSE)
 
 
-
+@public
 class NNTPRunner(Runner):
     def _dispose(self, mlist, msg, msgdata):
         # Get NNTP server connection information.
@@ -65,7 +61,7 @@ class NNTPRunner(Runner):
             try:
                 port = int(port)
             except (TypeError, ValueError):
-                log.exception('Bad [nntp]port value: {0}'.format(port))
+                log.exception('Bad [nntp]port value: {}'.format(port))
                 port = 119
         # Make sure we have the most up-to-date state
         if not msgdata.get('prepped'):
@@ -80,15 +76,15 @@ class NNTPRunner(Runner):
                                 password=config.nntp.password)
             conn.post(fp)
         except nntplib.NNTPTemporaryError:
-            log.exception('{0} NNTP error for {1}'.format(
+            log.exception('{} NNTP error for {}'.format(
                 msg.get('message-id', 'n/a'), mlist.fqdn_listname))
         except socket.error:
-            log.exception('{0} NNTP socket error for {1}'.format(
+            log.exception('{} NNTP socket error for {}'.format(
                 msg.get('message-id', 'n/a'), mlist.fqdn_listname))
         except Exception:
             # Some other exception occurred, which we definitely did not
             # expect, so set this message up for requeuing.
-            log.exception('{0} NNTP unexpected exception for {1}'.format(
+            log.exception('{} NNTP unexpected exception for {}'.format(
                 msg.get('message-id', 'n/a'), mlist.fqdn_listname))
             return True
         finally:
@@ -97,7 +93,6 @@ class NNTPRunner(Runner):
         return False
 
 
-
 def prepare_message(mlist, msg, msgdata):
     # If the newsgroup is moderated, we need to add this header for the Usenet
     # software to accept the posting, and not forward it on to the n.g.'s
@@ -170,7 +165,7 @@ def prepare_message(mlist, msg, msgdata):
     if len(dup_headers) % 2 != 0:
         # There are an odd number of headers; ignore the last one.
         bad_header = dup_headers.pop()
-        log.error('Ignoring odd [nntp]rewrite_duplicate_headers: {0}'.format(
+        log.error('Ignoring odd [nntp]rewrite_duplicate_headers: {}'.format(
             bad_header))
     dup_headers.reverse()
     while dup_headers:
diff --git a/src/mailman/runners/outgoing.py b/src/mailman/runners/outgoing.py
index 98c484e3f..3f21e3813 100644
--- a/src/mailman/runners/outgoing.py
+++ b/src/mailman/runners/outgoing.py
@@ -17,16 +17,12 @@
 
 """Outgoing runner."""
 
-__all__ = [
-    'OutgoingRunner',
-    ]
-
-
 import socket
 import logging
 
 from datetime import datetime
 from lazr.config import as_boolean, as_timedelta
+from mailman import public
 from mailman.config import config
 from mailman.core.runner import Runner
 from mailman.interfaces.bounce import BounceContext, IBounceProcessor
@@ -49,7 +45,7 @@ smtp_log = logging.getLogger('mailman.smtp')
 debug_log = logging.getLogger('mailman.debug')
 
 
-
+@public
 class OutgoingRunner(Runner):
     """The outgoing runner."""
 
@@ -92,7 +88,7 @@ class OutgoingRunner(Runner):
             # VERP every 'interval' number of times.
             msgdata['verp'] = (mlist.post_id % interval == 0)
         try:
-            debug_log.debug('[outgoing] {0}: {1}'.format(
+            debug_log.debug('[outgoing] {}: {}'.format(
                 self._func, msg.get('message-id', 'n/a')))
             self._func(mlist, msg, msgdata)
             self._logged = False
@@ -154,7 +150,7 @@ class OutgoingRunner(Runner):
                         if current_time > deliver_until:
                             smtp_log.error('Discarding message with '
                                            'persistent temporary failures: '
-                                           '{0}'.format(msg['message-id']))
+                                           '{}'.format(msg['message-id']))
                             return False
                     else:
                         # We made some progress, so keep trying to delivery
diff --git a/src/mailman/runners/pipeline.py b/src/mailman/runners/pipeline.py
index b7ea7fa34..3ec7499f2 100644
--- a/src/mailman/runners/pipeline.py
+++ b/src/mailman/runners/pipeline.py
@@ -22,16 +22,12 @@ through the 'preparation pipeline'.  This pipeline adds, deletes and modifies
 headers, calculates message recipients, and more.
 """
 
-__all__ = [
-    'PipelineRunner',
-    ]
-
-
+from mailman import public
 from mailman.core.pipelines import process
 from mailman.core.runner import Runner
 
 
-
+@public
 class PipelineRunner(Runner):
     def _dispose(self, mlist, msg, msgdata):
         # Process the message through the mailing list's pipeline.
diff --git a/src/mailman/runners/rest.py b/src/mailman/runners/rest.py
index 831f99997..5a76d22c1 100644
--- a/src/mailman/runners/rest.py
+++ b/src/mailman/runners/rest.py
@@ -17,15 +17,11 @@
 
 """Start the administrative HTTP server."""
 
-__all__ = [
-    'RESTRunner',
-    ]
-
-
 import signal
 import logging
 import threading
 
+from mailman import public
 from mailman.core.runner import Runner
 from mailman.rest.wsgiapp import make_server
 
@@ -33,7 +29,7 @@ from mailman.rest.wsgiapp import make_server
 log = logging.getLogger('mailman.http')
 
 
-
+@public
 class RESTRunner(Runner):
     # Don't install the standard signal handlers because as defined, they
     # won't actually stop the TCPServer started by .serve_forever().
@@ -54,7 +50,7 @@ class RESTRunner(Runner):
         # server.
         self._server = make_server()
         self._event = threading.Event()
-        def stopper(event, server):
+        def stopper(event, server):                 # flake8: noqa
             event.wait()
             server.shutdown()
         self._thread = threading.Thread(
diff --git a/src/mailman/runners/retry.py b/src/mailman/runners/retry.py
index 25743a5bd..f1af4f73c 100644
--- a/src/mailman/runners/retry.py
+++ b/src/mailman/runners/retry.py
@@ -17,18 +17,14 @@
 
 """Retry delivery."""
 
-__all__ = [
-    'RetryRunner',
-    ]
-
-
 import time
 
+from mailman import public
 from mailman.config import config
 from mailman.core.runner import Runner
 
 
-
+@public
 class RetryRunner(Runner):
     """Retry delivery."""
 
diff --git a/src/mailman/runners/tests/test_archiver.py b/src/mailman/runners/tests/test_archiver.py
index 8aaaec86e..79f04c236 100644
--- a/src/mailman/runners/tests/test_archiver.py
+++ b/src/mailman/runners/tests/test_archiver.py
@@ -17,11 +17,6 @@
 
 """Test the archive runner."""
 
-__all__ = [
-    'TestArchiveRunner',
-    ]
-
-
 import os
 import unittest
 
@@ -39,7 +34,6 @@ from mailman.utilities.datetime import RFC822_DATE_FMT, factory, now
 from zope.interface import implementer
 
 
-
 @implementer(IArchiver)
 class DummyArchiver:
     name = 'dummy'
@@ -80,7 +74,6 @@ class BrokenArchiver:
         raise RuntimeError('Cannot archive message')
 
 
-
 class TestArchiveRunner(unittest.TestCase):
     """Test the archive runner."""
 
@@ -282,4 +275,4 @@ First post!
         log_messages = mark.read()
         self.assertIn('Exception in "broken" archiver', log_messages)
         self.assertIn('RuntimeError: Cannot archive message', log_messages)
-        self.assertEqual(len(get_queue_messages('shunt')), 0)
+        get_queue_messages('shunt', expected_count=0)
diff --git a/src/mailman/runners/tests/test_bounce.py b/src/mailman/runners/tests/test_bounce.py
index 2fab646e4..e33ad9de2 100644
--- a/src/mailman/runners/tests/test_bounce.py
+++ b/src/mailman/runners/tests/test_bounce.py
@@ -17,13 +17,6 @@
 
 """Test the bounce runner."""
 
-__all__ = [
-    'TestBounceRunner',
-    'TestBounceRunnerBug876774',
-    'TestStyle',
-    ]
-
-
 import unittest
 
 from mailman.app.bounces import send_probe
@@ -43,7 +36,6 @@ from zope.component import getUtility
 from zope.interface import implementer
 
 
-
 class TestBounceRunner(unittest.TestCase):
     """Test the bounce runner."""
 
@@ -69,9 +61,7 @@ Message-Id: <first>
         [mailman]
         site_owner: postmaster@example.com
         """)
-
-    def tearDown(self):
-        config.pop('site owner')
+        self.addCleanup(config.pop, 'site owner')
 
     def test_does_no_processing(self):
         # If the mailing list does no bounce processing, the messages are
@@ -79,7 +69,7 @@ Message-Id: <first>
         self._mlist.process_bounces = False
         self._bounceq.enqueue(self._msg, self._msgdata)
         self._runner.run()
-        self.assertEqual(len(get_queue_messages('bounces')), 0)
+        get_queue_messages('bounces', expected_count=0)
         self.assertEqual(len(list(self._processor.events)), 0)
 
     def test_verp_detection(self):
@@ -87,7 +77,7 @@ Message-Id: <first>
         # event will be registered.
         self._bounceq.enqueue(self._msg, self._msgdata)
         self._runner.run()
-        self.assertEqual(len(get_queue_messages('bounces')), 0)
+        get_queue_messages('bounces', expected_count=0)
         events = list(self._processor.events)
         self.assertEqual(len(events), 1)
         self.assertEqual(events[0].email, 'anne@example.com')
@@ -115,7 +105,7 @@ Original-Recipient: rfc822; somebody@example.com
 """)
         self._bounceq.enqueue(nonfatal, self._msgdata)
         self._runner.run()
-        self.assertEqual(len(get_queue_messages('bounces')), 0)
+        get_queue_messages('bounces', expected_count=0)
         events = list(self._processor.events)
         self.assertEqual(len(events), 0)
 
@@ -127,7 +117,8 @@ Original-Recipient: rfc822; somebody@example.com
         #
         # Start be simulating a probe bounce.
         send_probe(self._member, self._msg)
-        message = get_queue_messages('virgin')[0].msg
+        items = get_queue_messages('virgin', expected_count=1)
+        message = items[0].msg
         bounce = message_from_string("""\
 To: {0}
 From: mail-daemon@example.com
@@ -136,7 +127,7 @@ Message-Id: <second>
 """.format(message['From']))
         self._bounceq.enqueue(bounce, self._msgdata)
         self._runner.run()
-        self.assertEqual(len(get_queue_messages('bounces')), 0)
+        get_queue_messages('bounces', expected_count=0)
         events = list(self._processor.events)
         self.assertEqual(len(events), 1)
         self.assertEqual(events[0].email, 'anne@example.com')
@@ -166,7 +157,7 @@ Original-Recipient: rfc822; bart@example.com
 """)
         self._bounceq.enqueue(dsn, self._msgdata)
         self._runner.run()
-        self.assertEqual(len(get_queue_messages('bounces')), 0)
+        get_queue_messages('bounces', expected_count=0)
         events = list(self._processor.events)
         self.assertEqual(len(events), 1)
         self.assertEqual(events[0].email, 'bart@example.com')
@@ -196,7 +187,7 @@ Original-Recipient: rfc822; bart@example.com
 """)
         self._bounceq.enqueue(dsn, self._msgdata)
         self._runner.run()
-        self.assertEqual(len(get_queue_messages('bounces')), 0)
+        get_queue_messages('bounces', expected_count=0)
         events = list(self._processor.events)
         self.assertEqual(len(events), 0)
 
@@ -215,7 +206,7 @@ Message-Id: <third>
         self._bounceq.enqueue(bogus, self._msgdata)
         mark = LogFileMark('mailman.bounce')
         self._runner.run()
-        self.assertEqual(len(get_queue_messages('bounces')), 0)
+        get_queue_messages('bounces', expected_count=0)
         events = list(self._processor.events)
         self.assertEqual(len(events), 0)
         line = mark.readline()
@@ -223,12 +214,10 @@ Message-Id: <third>
             line[-51:-1],
             'Bounce message w/no discernable addresses: <third>')
         # Here's the forwarded message to the site owners.
-        forwards = get_queue_messages('virgin')
-        self.assertEqual(len(forwards), 1)
-        self.assertEqual(forwards[0].msg['to'], 'postmaster@example.com')
+        items = get_queue_messages('virgin', expected_count=1)
+        self.assertEqual(items[0].msg['to'], 'postmaster@example.com')
 
 
-
 # Create a style for the mailing list which sets the absolute minimum
 # attributes.  In particular, this will not set the bogus `bounce_processing`
 # attribute which the default style set (before LP: #876774 was fixed).
@@ -244,7 +233,6 @@ class TestStyle:
         mailing_list.preferred_language = 'en'
 
 
-
 class TestBounceRunnerBug876774(unittest.TestCase):
     """Test LP: #876774.
 
@@ -261,15 +249,13 @@ class TestBounceRunnerBug876774(unittest.TestCase):
         self._style = TestStyle()
         self._style_manager = getUtility(IStyleManager)
         self._style_manager.register(self._style)
+        self.addCleanup(self._style_manager.unregister, self._style)
         # Now we can create the mailing list.
         self._mlist = create_list('test@example.com', style_name='test')
         self._bounceq = config.switchboards['bounces']
         self._processor = getUtility(IBounceProcessor)
         self._runner = make_testable_runner(BounceRunner, 'bounces')
 
-    def tearDown(self):
-        self._style_manager.unregister(self._style)
-
     def test_bug876774(self):
         # LP: #876774, see above.
         bounce = message_from_string("""\
@@ -281,6 +267,6 @@ Message-Id: <first>
         self._bounceq.enqueue(bounce, dict(listid='test.example.com'))
         self.assertEqual(len(self._bounceq.files), 1)
         self._runner.run()
-        self.assertEqual(len(get_queue_messages('bounces')), 0)
+        get_queue_messages('bounces', expected_count=0)
         events = list(self._processor.events)
         self.assertEqual(len(events), 0)
diff --git a/src/mailman/runners/tests/test_confirm.py b/src/mailman/runners/tests/test_confirm.py
index 39cf85387..7dc2403fc 100644
--- a/src/mailman/runners/tests/test_confirm.py
+++ b/src/mailman/runners/tests/test_confirm.py
@@ -17,11 +17,6 @@
 
 """Test the `confirm` command."""
 
-__all__ = [
-    'TestConfirm',
-    ]
-
-
 import unittest
 
 from datetime import datetime
@@ -39,7 +34,6 @@ from mailman.testing.layers import ConfigLayer
 from zope.component import getUtility
 
 
-
 class TestConfirm(unittest.TestCase):
     """Test confirmations."""
 
@@ -57,7 +51,7 @@ class TestConfirm(unittest.TestCase):
             self._token, token_owner, member = registrar.register(anne)
 
     def test_confirm_with_re_prefix(self):
-        subject = 'Re: confirm {0}'.format(self._token)
+        subject = 'Re: confirm {}'.format(self._token)
         msg = mfs("""\
 From: anne@example.org
 To: test-confirm@example.com
@@ -77,7 +71,7 @@ To: test-confirm@example.com
         self.assertEqual(address.email, 'anne@example.org')
 
     def test_confirm_with_random_ascii_prefix(self):
-        subject = '\x99AW: confirm {0}'.format(self._token)
+        subject = '\x99AW: confirm {}'.format(self._token)
         msg = mfs("""\
 From: anne@example.org
 To: test-confirm@example.com
@@ -100,8 +94,8 @@ To: test-confirm@example.com
         # Clear out the virgin queue so that the test below only sees the
         # reply to the confirmation message.
         get_queue_messages('virgin')
-        subject = 'Re: confirm {0}'.format(self._token)
-        to = 'test-confirm+{0}@example.com'.format(self._token)
+        subject = 'Re: confirm {}'.format(self._token)
+        to = 'test-confirm+{}@example.com'.format(self._token)
         msg = mfs("""\
 From: Anne Person <anne@example.org>
 MIME-Version: 1.0
@@ -151,17 +145,16 @@ Franziskanerstra=C3=9Fe
         self.assertEqual(address.verified_on, datetime(2005, 8, 1, 7, 49, 23))
         address = manager.get_address('anne@example.org')
         self.assertEqual(address.email, 'anne@example.org')
-        messages = get_queue_messages('virgin')
-        self.assertEqual(len(messages), 1)
-        self.assertEqual(messages[0].msgdata['recipients'],
+        items = get_queue_messages('virgin', expected_count=1)
+        self.assertEqual(items[0].msgdata['recipients'],
                          set(['anne@example.org']))
 
     def test_confirm_with_no_command_in_utf8_body(self):
         # Clear out the virgin queue so that the test below only sees the
         # reply to the confirmation message.
         get_queue_messages('virgin')
-        subject = 'Re: confirm {0}'.format(self._token)
-        to = 'test-confirm+{0}@example.com'.format(self._token)
+        subject = 'Re: confirm {}'.format(self._token)
+        to = 'test-confirm+{}@example.com'.format(self._token)
         msg = mfs("""\
 From: Anne Person <anne@example.org>
 MIME-Version: 1.0
@@ -184,9 +177,8 @@ Franziskanerstra=C3=9Fe
         self.assertEqual(address.verified_on, datetime(2005, 8, 1, 7, 49, 23))
         address = manager.get_address('anne@example.org')
         self.assertEqual(address.email, 'anne@example.org')
-        messages = get_queue_messages('virgin')
-        self.assertEqual(len(messages), 1)
-        self.assertEqual(messages[0].msgdata['recipients'],
+        items = get_queue_messages('virgin', expected_count=1)
+        self.assertEqual(items[0].msgdata['recipients'],
                          set(['anne@example.org']))
 
     def test_double_confirmation(self):
@@ -196,8 +188,8 @@ Franziskanerstra=C3=9Fe
         # Clear out the virgin queue so that the test below only sees the
         # reply to the confirmation message.
         get_queue_messages('virgin')
-        subject = 'Re: confirm {0}'.format(self._token)
-        to = 'test-confirm+{0}@example.com'.format(self._token)
+        subject = 'Re: confirm {}'.format(self._token)
+        to = 'test-confirm+{}@example.com'.format(self._token)
         msg = mfs("""\
 From: Anne Person <anne@example.org>
 
@@ -213,13 +205,12 @@ From: Anne Person <anne@example.org>
         user = manager.get_user('anne@example.org')
         self.assertEqual(list(user.addresses)[0].email, 'anne@example.org')
         # Make sure that the confirmation was not attempted twice.
-        messages = get_queue_messages('virgin')
-        self.assertEqual(len(messages), 1)
+        items = get_queue_messages('virgin', expected_count=1)
         # Search the contents of the results message.  There should be just
         # one 'Confirmation email' line.
         confirmation_lines = []
         in_results = False
-        for line in body_line_iterator(messages[0].msg):
+        for line in body_line_iterator(items[0].msg):
             line = line.strip()
             if in_results:
                 if line.startswith('- Done'):
@@ -229,7 +220,7 @@ From: Anne Person <anne@example.org>
             if line.strip() == '- Results:':
                 in_results = True
         self.assertEqual(len(confirmation_lines), 1)
-        self.assertFalse('did not match' in confirmation_lines[0])
+        self.assertNotIn('did not match', confirmation_lines[0])
 
     def test_welcome_message_after_confirmation(self):
         # Confirmations with a welcome message set.
@@ -241,8 +232,8 @@ From: Anne Person <anne@example.org>
         # Clear out the virgin queue so that the test below only sees the
         # reply to the confirmation message.
         get_queue_messages('virgin')
-        subject = 'Re: confirm {0}'.format(self._token)
-        to = 'test-confirm+{0}@example.com'.format(self._token)
+        subject = 'Re: confirm {}'.format(self._token)
+        to = 'test-confirm+{}@example.com'.format(self._token)
         msg = mfs("""\
 From: Anne Person <anne@example.org>
 
@@ -254,8 +245,7 @@ From: Anne Person <anne@example.org>
         self._runner.run()
         # Now there's a email command notification and a welcome message.  All
         # we care about for this test is the welcome message.
-        messages = get_queue_messages('virgin', sort_on='subject')
-        self.assertEqual(len(messages), 2)
-        message = messages[1].msg
-        self.assertEqual(str(message['subject']),
+        items = get_queue_messages('virgin', sort_on='subject',
+                                   expected_count=2)
+        self.assertEqual(str(items[1].msg['subject']),
                          'Welcome to the "Test" mailing list')
diff --git a/src/mailman/runners/tests/test_digest.py b/src/mailman/runners/tests/test_digest.py
index 279ae36d8..f767f78d4 100644
--- a/src/mailman/runners/tests/test_digest.py
+++ b/src/mailman/runners/tests/test_digest.py
@@ -17,12 +17,6 @@
 
 """Test the digest runner."""
 
-__all__ = [
-    'TestDigest',
-    'TestI18nDigest',
-    ]
-
-
 import unittest
 
 from email.iterators import _structure as structure
@@ -42,7 +36,6 @@ from mailman.testing.layers import ConfigLayer
 from string import Template
 
 
-
 class TestDigest(unittest.TestCase):
     """Test the digest runner."""
 
@@ -62,12 +55,11 @@ class TestDigest(unittest.TestCase):
     def _check_virgin_queue(self):
         # There should be two messages in the virgin queue: the digest as
         # plain-text and as multipart.
-        messages = get_queue_messages('virgin')
-        self.assertEqual(len(messages), 2)
+        items = get_queue_messages('virgin', expected_count=2)
         self.assertEqual(
-            sorted(item.msg.get_content_type() for item in messages),
+            sorted(item.msg.get_content_type() for item in items),
             ['multipart/mixed', 'text/plain'])
-        for item in messages:
+        for item in items:
             self.assertEqual(item.msg['subject'],
                              'Test Digest, Vol 1, Issue 1')
 
@@ -132,8 +124,7 @@ Here is message $i
         # Run the digest runner to create the MIME and RFC 1153 digests.
         runner = make_testable_runner(DigestRunner)
         runner.run()
-        items = get_queue_messages('virgin')
-        self.assertEqual(len(items), 2)
+        items = get_queue_messages('virgin', expected_count=2)
         # Find the MIME one.
         mime_digest = None
         for item in items:
@@ -166,8 +157,7 @@ multipart/mixed
         make_digest_messages(self._mlist)
         # There should be one message in the outgoing queue, destined for
         # Bart, formatted as a MIME digest.
-        items = get_queue_messages('virgin')
-        self.assertEqual(len(items), 1)
+        items = get_queue_messages('virgin', expected_count=1)
         # Bart is the only recipient.
         self.assertEqual(items[0].msgdata['recipients'],
                          set(['bperson@example.com']))
@@ -192,8 +182,7 @@ multipart/mixed
         make_digest_messages(self._mlist)
         # There should be one message in the outgoing queue, destined for
         # Bart, formatted as a MIME digest.
-        items = get_queue_messages('virgin')
-        self.assertEqual(len(items), 1)
+        items = get_queue_messages('virgin', expected_count=1)
         # Bart is the only recipient.
         self.assertEqual(items[0].msgdata['recipients'],
                          set(['bperson@example.com']))
@@ -210,7 +199,6 @@ multipart/mixed
 """)
 
 
-
 class TestI18nDigest(unittest.TestCase):
     layer = ConfigLayer
     maxDiff = None
@@ -252,12 +240,11 @@ Content-Transfer-Encoding: 7bit
         self._runner.run()
         # There are two digests in the virgin queue; one is the MIME digest
         # and the other is the RFC 1153 digest.
-        messages = get_queue_messages('virgin')
-        self.assertEqual(len(messages), 2)
-        if messages[0].msg.is_multipart():
-            mime, rfc1153 = messages[0].msg, messages[1].msg
+        items = get_queue_messages('virgin', expected_count=2)
+        if items[0].msg.is_multipart():
+            mime, rfc1153 = items[0].msg, items[1].msg
         else:
-            rfc1153, mime = messages[0].msg, messages[1].msg
+            rfc1153, mime = items[0].msg, items[1].msg
         # The MIME version contains a mix of French and Japanese.  The digest
         # chrome added by Mailman is in French.
         self.assertEqual(mime['subject'].encode(),
diff --git a/src/mailman/runners/tests/test_incoming.py b/src/mailman/runners/tests/test_incoming.py
index d813cc34b..c8878c0c5 100644
--- a/src/mailman/runners/tests/test_incoming.py
+++ b/src/mailman/runners/tests/test_incoming.py
@@ -17,11 +17,6 @@
 
 """Test the incoming queue runner."""
 
-__all__ = [
-    'TestIncoming',
-    ]
-
-
 import unittest
 
 from mailman.app.lifecycle import create_list
@@ -34,7 +29,6 @@ from mailman.testing.helpers import (
 from mailman.testing.layers import ConfigLayer
 
 
-
 class Chain(TerminalChainBase):
     name = 'test'
     description = 'a test chain'
@@ -47,7 +41,6 @@ class Chain(TerminalChainBase):
         config.switchboards['out'].enqueue(msg, msgdata)
 
 
-
 class TestIncoming(unittest.TestCase):
     """Test the incoming queue runner."""
 
@@ -73,9 +66,8 @@ To: test@example.com
         msgdata = dict(listid='test.example.com')
         config.switchboards['in'].enqueue(self._msg, msgdata)
         self._in.run()
-        messages = get_queue_messages('out')
-        self.assertEqual(len(messages), 1)
-        self.assertEqual(messages[0].msgdata.get('marker'), 'posting')
+        items = get_queue_messages('out', expected_count=1)
+        self.assertEqual(items[0].msgdata.get('marker'), 'posting')
 
     def test_owner(self):
         # A message posted to the list goes through the posting chain.
@@ -83,6 +75,5 @@ To: test@example.com
                        to_owner=True)
         config.switchboards['in'].enqueue(self._msg, msgdata)
         self._in.run()
-        messages = get_queue_messages('out')
-        self.assertEqual(len(messages), 1)
-        self.assertEqual(messages[0].msgdata.get('marker'), 'owner')
+        items = get_queue_messages('out', expected_count=1)
+        self.assertEqual(items[0].msgdata.get('marker'), 'owner')
diff --git a/src/mailman/runners/tests/test_join.py b/src/mailman/runners/tests/test_join.py
index 239d8e2ef..0f24f3847 100644
--- a/src/mailman/runners/tests/test_join.py
+++ b/src/mailman/runners/tests/test_join.py
@@ -17,12 +17,6 @@
 
 """Test mailing list joins."""
 
-__all__ = [
-    'TestJoin',
-    'TestJoinWithDigests',
-    ]
-
-
 import unittest
 
 from email.iterators import body_line_iterator
@@ -34,13 +28,12 @@ from mailman.interfaces.subscriptions import ISubscriptionService, TokenOwner
 from mailman.interfaces.usermanager import IUserManager
 from mailman.runners.command import CommandRunner
 from mailman.testing.helpers import (
-    get_queue_messages, make_testable_runner, reset_the_world,
+    get_queue_messages, make_testable_runner,
     specialized_message_from_string as mfs)
 from mailman.testing.layers import ConfigLayer
 from zope.component import getUtility
 
 
-
 class TestJoin(unittest.TestCase):
     """Test mailing list joins."""
 
@@ -52,9 +45,6 @@ class TestJoin(unittest.TestCase):
         self._commandq = config.switchboards['command']
         self._runner = make_testable_runner(CommandRunner, 'command')
 
-    def tearDown(self):
-        reset_the_world()
-
     def test_double_confirmation(self):
         # A join request comes in using both the -join address and the word
         # 'subscribe' in the first line of the body.  This should produce just
@@ -74,16 +64,16 @@ subscribe
         # There will be two messages in the queue.  The first one is a reply
         # to Anne notifying her of the status of her command email.  The
         # second one is the confirmation message of her join request.
-        messages = get_queue_messages('virgin', sort_on='subject')
-        self.assertEqual(len(messages), 2)
-        self.assertTrue(str(messages[1].msg['subject']).startswith('confirm'))
-        self.assertEqual(messages[0].msg['subject'],
+        items = get_queue_messages('virgin', sort_on='subject',
+                                   expected_count=2)
+        self.assertTrue(str(items[1].msg['subject']).startswith('confirm'))
+        self.assertEqual(items[0].msg['subject'],
                          'The results of your email commands')
         # Search the contents of the results message.  There should be just
         # one 'Confirmation email' line.
         confirmation_lines = []
         in_results = False
-        for line in body_line_iterator(messages[0].msg):
+        for line in body_line_iterator(items[0].msg):
             line = line.strip()
             if in_results:
                 if line.startswith('- Done'):
@@ -95,7 +85,7 @@ subscribe
         # There should be exactly one confirmation line.
         self.assertEqual(len(confirmation_lines), 1)
         # And the confirmation line should name Anne's email address.
-        self.assertTrue('anne@example.org' in confirmation_lines[0])
+        self.assertIn('anne@example.org', confirmation_lines[0])
 
     def test_join_when_already_a_member(self):
         anne = getUtility(IUserManager).create_user('anne@example.org')
@@ -113,15 +103,14 @@ Subject: join
         # There will be one message in the queue - a reply to Anne notifying
         # her of the status of her command email.  Because Anne is already
         # subscribed to the list, she gets and needs no confirmation.
-        messages = get_queue_messages('virgin')
-        self.assertEqual(len(messages), 1)
-        self.assertEqual(messages[0].msg['subject'],
+        items = get_queue_messages('virgin', expected_count=1)
+        self.assertEqual(items[0].msg['subject'],
                          'The results of your email commands')
         # Search the contents of the results message.  There should be just
         # one 'Confirmation email' line.
         confirmation_lines = []
         in_results = False
-        for line in body_line_iterator(messages[0].msg):
+        for line in body_line_iterator(items[0].msg):
             line = line.strip()
             if in_results:
                 if line.startswith('- Done'):
@@ -133,10 +122,9 @@ Subject: join
         # There should be exactly one confirmation line.
         self.assertEqual(len(confirmation_lines), 1)
         # And the confirmation line should name Anne's email address.
-        self.assertTrue('anne@example.org' in confirmation_lines[0])
+        self.assertIn('anne@example.org', confirmation_lines[0])
 
 
-
 class TestJoinWithDigests(unittest.TestCase):
     """Test mailing list joins with the digests=<no|mime|plain> argument."""
 
@@ -147,17 +135,14 @@ class TestJoinWithDigests(unittest.TestCase):
         self._commandq = config.switchboards['command']
         self._runner = make_testable_runner(CommandRunner, 'command')
 
-    def tearDown(self):
-        reset_the_world()
-
     def _confirm(self):
         # There will be two messages in the queue - the confirmation messages,
         # and a reply to Anne notifying her of the status of her command
         # email.  We need to dig the confirmation token out of the Subject
         # header of the latter so that we can confirm the subscription.
-        messages = get_queue_messages('virgin', sort_on='subject')
-        self.assertEqual(len(messages), 2)
-        subject_words = str(messages[1].msg['subject']).split()
+        items = get_queue_messages('virgin', sort_on='subject',
+                                   expected_count=2)
+        subject_words = str(items[1].msg['subject']).split()
         self.assertEqual(subject_words[0], 'confirm')
         token = subject_words[1]
         token, token_owner, rmember = IRegistrar(self._mlist).confirm(token)
diff --git a/src/mailman/runners/tests/test_lmtp.py b/src/mailman/runners/tests/test_lmtp.py
index 69343c857..9d86af2dc 100644
--- a/src/mailman/runners/tests/test_lmtp.py
+++ b/src/mailman/runners/tests/test_lmtp.py
@@ -17,11 +17,6 @@
 
 """Tests for the LMTP server."""
 
-__all__ = [
-    'TestLMTP',
-    ]
-
-
 import os
 import smtplib
 import unittest
@@ -34,7 +29,6 @@ from mailman.testing.helpers import get_lmtp_client, get_queue_messages
 from mailman.testing.layers import LMTPLayer
 
 
-
 class TestLMTP(unittest.TestCase):
     """Test various aspects of the LMTP server."""
 
@@ -45,9 +39,7 @@ class TestLMTP(unittest.TestCase):
             self._mlist = create_list('test@example.com')
         self._lmtp = get_lmtp_client(quiet=True)
         self._lmtp.lhlo('remote.example.org')
-
-    def tearDown(self):
-        self._lmtp.close()
+        self.addCleanup(self._lmtp.close)
 
     def test_message_id_required(self):
         # The message is rejected if it does not have a Message-ID header.
@@ -73,9 +65,8 @@ Message-ID: <ant>
 Subject: This has a Message-ID but no Message-ID-Hash
 
 """)
-        messages = get_queue_messages('in')
-        self.assertEqual(len(messages), 1)
-        self.assertEqual(messages[0].msg['message-id-hash'],
+        items = get_queue_messages('in', expected_count=1)
+        self.assertEqual(items[0].msg['message-id-hash'],
                          'MS6QLWERIJLGCRF44J7USBFDELMNT2BW')
 
     def test_original_message_id_hash_is_overwritten(self):
@@ -87,11 +78,10 @@ Message-ID-Hash: IGNOREME
 Subject: This has a Message-ID but no Message-ID-Hash
 
 """)
-        messages = get_queue_messages('in')
-        self.assertEqual(len(messages), 1)
-        all_headers = messages[0].msg.get_all('message-id-hash')
+        items = get_queue_messages('in', expected_count=1)
+        all_headers = items[0].msg.get_all('message-id-hash')
         self.assertEqual(len(all_headers), 1)
-        self.assertEqual(messages[0].msg['message-id-hash'],
+        self.assertEqual(items[0].msg['message-id-hash'],
                          'MS6QLWERIJLGCRF44J7USBFDELMNT2BW')
 
     def test_received_time(self):
@@ -103,9 +93,8 @@ Subject: This has no Message-ID header
 Message-ID: <ant>
 
 """)
-        messages = get_queue_messages('in')
-        self.assertEqual(len(messages), 1)
-        self.assertEqual(messages[0].msgdata['received_time'],
+        items = get_queue_messages('in', expected_count=1)
+        self.assertEqual(items[0].msgdata['received_time'],
                          datetime(2005, 8, 1, 7, 49, 23))
 
     def test_queue_directory(self):
@@ -157,8 +146,8 @@ Subject: This should not be recognized as a join command
 
 """)
         # The message is in the incoming queue but not the command queue.
-        self.assertEqual(len(get_queue_messages('in')), 1)
-        self.assertEqual(len(get_queue_messages('command')), 0)
+        get_queue_messages('in', expected_count=1)
+        get_queue_messages('command', expected_count=0)
 
     def test_mailing_list_with_subaddress_command(self):
         # Like above, but we can still send a command to the mailing list.
@@ -173,11 +162,10 @@ Subject: This will be recognized as a join command.
 
 """)
         # The message is in the command queue but not the incoming queue.
-        self.assertEqual(len(get_queue_messages('in')), 0)
-        self.assertEqual(len(get_queue_messages('command')), 1)
+        get_queue_messages('in', expected_count=0)
+        get_queue_messages('command', expected_count=1)
 
 
-
 class TestBugs(unittest.TestCase):
     """Test some LMTP related bugs."""
 
@@ -198,9 +186,8 @@ Subject: My subject
 Message-ID: <alpha>
 
 """)
-        messages = get_queue_messages('in')
-        self.assertEqual(len(messages), 1)
-        self.assertEqual(messages[0].msgdata['listid'],
+        items = get_queue_messages('in', expected_count=1)
+        self.assertEqual(items[0].msgdata['listid'],
                          'my-list.example.com')
 
     def test_issue140(self):
@@ -215,6 +202,5 @@ Message-ID: <alpha>
 
 \xa0
 """)
-        messages = get_queue_messages('in')
-        self.assertEqual(len(messages), 1)
-        self.assertEqual(messages[0].msg['message-id'], '<alpha>')
+        items = get_queue_messages('in', expected_count=1)
+        self.assertEqual(items[0].msg['message-id'], '<alpha>')
diff --git a/src/mailman/runners/tests/test_nntp.py b/src/mailman/runners/tests/test_nntp.py
index 6ce3c1afc..1cf5cfc61 100644
--- a/src/mailman/runners/tests/test_nntp.py
+++ b/src/mailman/runners/tests/test_nntp.py
@@ -17,12 +17,6 @@
 
 """Test the NNTP runner and related utilities."""
 
-__all__ = [
-    'TestPrepareMessage',
-    'TestNNTPRunner',
-    ]
-
-
 import socket
 import nntplib
 import unittest
@@ -38,7 +32,6 @@ from mailman.testing.layers import ConfigLayer
 from unittest import mock
 
 
-
 class TestPrepareMessage(unittest.TestCase):
     """Test message preparation."""
 
@@ -228,7 +221,6 @@ Testing
         self.assertEqual(fakes, ['one', 'two', 'three'])
 
 
-
 class TestNNTPRunner(unittest.TestCase):
     """The NNTP runner hands messages off to the NNTP server."""
 
@@ -331,10 +323,9 @@ Testing
         log_message = mark.readline()[:-1]
         self.assertTrue(log_message.endswith(
             'NNTP unexpected exception for test@example.com'))
-        messages = get_queue_messages('nntp')
-        self.assertEqual(len(messages), 1)
-        self.assertEqual(messages[0].msgdata['listid'], 'test.example.com')
-        self.assertEqual(messages[0].msg['subject'], 'A newsgroup posting')
+        items = get_queue_messages('nntp', expected_count=1)
+        self.assertEqual(items[0].msgdata['listid'], 'test.example.com')
+        self.assertEqual(items[0].msg['subject'], 'A newsgroup posting')
 
     @mock.patch('nntplib.NNTP', side_effect=nntplib.NNTPTemporaryError)
     def test_connection_never_gets_quit_after_failures(self, class_mock):
diff --git a/src/mailman/runners/tests/test_outgoing.py b/src/mailman/runners/tests/test_outgoing.py
index bc6e54bed..102a74d10 100644
--- a/src/mailman/runners/tests/test_outgoing.py
+++ b/src/mailman/runners/tests/test_outgoing.py
@@ -17,20 +17,11 @@
 
 """Test the outgoing runner."""
 
-__all__ = [
-    'TestOnce',
-    'TestSocketError',
-    'TestSomeRecipientsFailed',
-    'TestVERPSettings',
-    ]
-
-
 import os
 import socket
 import logging
 import unittest
 
-from contextlib import contextmanager
 from datetime import datetime, timedelta
 from lazr.config import as_timedelta
 from mailman.app.bounces import send_probe
@@ -44,14 +35,13 @@ from mailman.interfaces.pending import IPendings
 from mailman.interfaces.usermanager import IUserManager
 from mailman.runners.outgoing import OutgoingRunner
 from mailman.testing.helpers import (
-    LogFileMark, get_queue_messages, make_testable_runner,
+    LogFileMark, configuration, get_queue_messages, make_testable_runner,
     specialized_message_from_string as message_from_string)
 from mailman.testing.layers import ConfigLayer, SMTPLayer
 from mailman.utilities.datetime import factory, now
 from zope.component import getUtility
 
 
-
 def run_once(runner):
     """Predicate for make_testable_runner().
 
@@ -60,17 +50,6 @@ def run_once(runner):
     return True
 
 
-@contextmanager
-def temporary_config(name, settings):
-    """Temporarily set a configuration (use in a with-statement)."""
-    config.push(name, settings)
-    try:
-        yield
-    finally:
-        config.pop(name)
-
-
-
 class TestOnce(unittest.TestCase):
     """Test outgoing runner message disposition."""
 
@@ -96,17 +75,16 @@ Message-Id: <first>
         self._outq.enqueue(self._msg, self._msgdata,
                            tolist=True, listid='test.example.com')
         self._runner.run()
-        items = get_queue_messages('out')
-        self.assertEqual(len(items), 1)
+        items = get_queue_messages('out', expected_count=1)
         self.assertEqual(items[0].msgdata['deliver_after'], deliver_after)
         self.assertEqual(items[0].msg['message-id'], '<first>')
 
 
-
 captured_mlist = None
 captured_msg = None
 captured_msgdata = None
 
+
 def capture(mlist, msg, msgdata):
     global captured_mlist, captured_msg, captured_msgdata
     captured_mlist = mlist
@@ -128,6 +106,7 @@ class TestVERPSettings(unittest.TestCase):
         [mta]
         outgoing: mailman.runners.tests.test_outgoing.capture
         """)
+        self.addCleanup(config.pop, 'fake outgoing')
         # Reset the captured data.
         captured_mlist = None
         captured_msg = None
@@ -142,9 +121,6 @@ Message-Id: <first>
 
 """)
 
-    def tearDown(self):
-        config.pop('fake outgoing')
-
     def test_delivery_callback(self):
         # Test that the configuration variable calls the appropriate callback.
         self._outq.enqueue(self._msg, {}, listid='test.example.com')
@@ -170,10 +146,7 @@ Message-Id: <first>
         msgdata = {}
         self._mlist.personalize = Personalization.individual
         self._outq.enqueue(self._msg, msgdata, listid='test.example.com')
-        with temporary_config('personalize', """
-        [mta]
-        verp_personalized_deliveries: yes
-        """):
+        with configuration('mta', verp_personalized_deliveries='yes'):
             self._runner.run()
         self.assertTrue(captured_msgdata['verp'])
 
@@ -183,10 +156,7 @@ Message-Id: <first>
         msgdata = {}
         self._mlist.personalize = Personalization.full
         self._outq.enqueue(self._msg, msgdata, listid='test.example.com')
-        with temporary_config('personalize', """
-        [mta]
-        verp_personalized_deliveries: yes
-        """):
+        with configuration('mta', verp_personalized_deliveries='yes'):
             self._runner.run()
         self.assertTrue(captured_msgdata['verp'])
 
@@ -197,56 +167,43 @@ Message-Id: <first>
         self._mlist.personalize = Personalization.full
         self._outq.enqueue(self._msg, msgdata, listid='test.example.com')
         self._runner.run()
-        self.assertFalse('verp' in captured_msgdata)
+        self.assertNotIn('verp', captured_msgdata)
 
     def test_verp_never(self):
         # Never VERP when the interval is zero.
         msgdata = {}
         self._outq.enqueue(self._msg, msgdata, listid='test.example.com')
-        with temporary_config('personalize', """
-        [mta]
-        verp_delivery_interval: 0
-        """):
+        with configuration('mta', verp_delivery_interval=0):
             self._runner.run()
-        self.assertEqual(captured_msgdata['verp'], False)
+        self.assertFalse(captured_msgdata['verp'])
 
     def test_verp_always(self):
         # Always VERP when the interval is one.
         msgdata = {}
         self._outq.enqueue(self._msg, msgdata, listid='test.example.com')
-        with temporary_config('personalize', """
-        [mta]
-        verp_delivery_interval: 1
-        """):
+        with configuration('mta', verp_delivery_interval=1):
             self._runner.run()
-        self.assertEqual(captured_msgdata['verp'], True)
+        self.assertTrue(captured_msgdata['verp'])
 
     def test_verp_on_interval_match(self):
         # VERP every so often, when the post_id matches.
         self._mlist.post_id = 5
         msgdata = {}
         self._outq.enqueue(self._msg, msgdata, listid='test.example.com')
-        with temporary_config('personalize', """
-        [mta]
-        verp_delivery_interval: 5
-        """):
+        with configuration('mta', verp_delivery_interval=5):
             self._runner.run()
-        self.assertEqual(captured_msgdata['verp'], True)
+        self.assertTrue(captured_msgdata['verp'])
 
     def test_no_verp_on_interval_miss(self):
         # VERP every so often, when the post_id matches.
         self._mlist.post_id = 4
         msgdata = {}
         self._outq.enqueue(self._msg, msgdata, listid='test.example.com')
-        with temporary_config('personalize', """
-            [mta]
-            verp_delivery_interval: 5
-            """):
+        with configuration('mta', verp_delivery_interval=5):
             self._runner.run()
-        self.assertEqual(captured_msgdata['verp'], False)
+        self.assertFalse(captured_msgdata['verp'])
 
 
-
 def raise_socket_error(mlist, msg, msgdata):
     raise socket.error
 
@@ -264,6 +221,7 @@ class TestSocketError(unittest.TestCase):
         [mta]
         outgoing: mailman.runners.tests.test_outgoing.raise_socket_error
         """)
+        self.addCleanup(config.pop, 'fake outgoing')
         self._mlist = create_list('test@example.com')
         self._outq = config.switchboards['out']
         self._runner = make_testable_runner(OutgoingRunner, 'out', run_once)
@@ -274,9 +232,6 @@ Message-Id: <first>
 
 """)
 
-    def tearDown(self):
-        config.pop('fake outgoing')
-
     def test_error_with_port_0(self):
         # Test the code path where a socket.error is raised in the delivery
         # function, and the MTA port is set to zero.  The only real effect of
@@ -286,10 +241,7 @@ Message-Id: <first>
         filename = error_log.handlers[0].filename
         filepos = os.stat(filename).st_size
         self._outq.enqueue(self._msg, {}, listid='test.example.com')
-        with temporary_config('port 0', """
-            [mta]
-            smtp_port: 0
-            """):
+        with configuration('mta', smtp_port=0):
             self._runner.run()
         with open(filename) as fp:
             fp.seek(filepos)
@@ -307,10 +259,7 @@ Message-Id: <first>
         # the current file position.
         mark = LogFileMark('mailman.error')
         self._outq.enqueue(self._msg, {}, listid='test.example.com')
-        with temporary_config('port 0', """
-            [mta]
-            smtp_port: 2112
-            """):
+        with configuration('mta', smtp_port=2112):
             self._runner.run()
         line = mark.readline()
         # The log line will contain a variable timestamp, the PID, and a
@@ -320,7 +269,6 @@ Message-Id: <first>
             'Cannot connect to SMTP server localhost on port 2112')
 
 
-
 temporary_failures = []
 permanent_failures = []
 
@@ -346,6 +294,7 @@ class TestSomeRecipientsFailed(unittest.TestCase):
        [mta]
        outgoing: mailman.runners.tests.test_outgoing.raise_SomeRecipientsFailed
         """)
+        self.addCleanup(config.pop, 'fake outgoing')
         self._mlist = create_list('test@example.com')
         self._outq = config.switchboards['out']
         self._runner = make_testable_runner(OutgoingRunner, 'out', run_once)
@@ -356,9 +305,6 @@ Message-Id: <first>
 
 """)
 
-    def tearDown(self):
-        config.pop('fake outgoing')
-
     def test_probe_failure(self):
         # When a probe message fails during SMTP, a bounce event is recorded
         # with the proper bounce context.
@@ -377,7 +323,7 @@ Message-Id: <first>
         self.assertEqual(event.timestamp, datetime(2005, 8, 1, 7, 49, 23))
         self.assertEqual(event.message_id, '<first>')
         self.assertEqual(event.context, BounceContext.probe)
-        self.assertEqual(event.processed, False)
+        self.assertFalse(event.processed)
 
     def test_confirmed_probe_failure(self):
         # This time, a probe also fails, but for some reason the probe token
@@ -439,8 +385,7 @@ Message-Id: <first>
         self._runner.run()
         events = list(self._processor.unprocessed)
         self.assertEqual(len(events), 0)
-        items = get_queue_messages('retry')
-        self.assertEqual(len(items), 1)
+        items = get_queue_messages('retry', expected_count=1)
         self.assertEqual(self._msg.as_string(), items[0].msg.as_string())
         # The metadata has three keys which are used two decide whether the
         # next temporary failure should be retried.
@@ -460,10 +405,9 @@ Message-Id: <first>
         self._runner.run()
         events = list(self._processor.unprocessed)
         self.assertEqual(len(events), 0)
-        items = get_queue_messages('retry')
         # There's still only one item in the retry queue, but the metadata
         # contains both temporary failures.
-        self.assertEqual(len(items), 1)
+        items = get_queue_messages('retry', expected_count=1)
         self.assertEqual(items[0].msgdata['last_recip_count'], 2)
         self.assertEqual(items[0].msgdata['recipients'],
                          ['cris@example.com', 'dave@example.com'])
@@ -484,8 +428,7 @@ Message-Id: <first>
         self.assertEqual(events[1].email, 'fred@example.com')
         self.assertEqual(events[1].context, BounceContext.normal)
         # Let's look at the temporary failures.
-        items = get_queue_messages('retry')
-        self.assertEqual(len(items), 1)
+        items = get_queue_messages('retry', expected_count=1)
         self.assertEqual(items[0].msgdata['recipients'],
                          ['gwen@example.com', 'herb@example.com'])
 
@@ -504,8 +447,7 @@ Message-Id: <first>
         self._outq.enqueue(self._msg, msgdata, listid='test.example.com')
         self._runner.run()
         # The retry queue should have our message waiting to be retried.
-        items = get_queue_messages('retry')
-        self.assertEqual(len(items), 1)
+        items = get_queue_messages('retry', expected_count=1)
         self.assertEqual(items[0].msgdata['deliver_until'], deliver_until)
         self.assertEqual(items[0].msgdata['recipients'],
                          ['iona@example.com', 'jeff@example.com'])
@@ -526,8 +468,8 @@ Message-Id: <first>
         mark = LogFileMark('mailman.smtp')
         self._runner.run()
         # There should be no message in the retry or outgoing queues.
-        self.assertEqual(len(get_queue_messages('retry')), 0)
-        self.assertEqual(len(get_queue_messages('out')), 0)
+        get_queue_messages('retry', expected_count=0)
+        get_queue_messages('out', expected_count=0)
         # There should be a log message in the smtp log indicating that the
         # message has been discarded.
         line = mark.readline()
diff --git a/src/mailman/runners/tests/test_owner.py b/src/mailman/runners/tests/test_owner.py
index e5d319b7a..48ccaaba0 100644
--- a/src/mailman/runners/tests/test_owner.py
+++ b/src/mailman/runners/tests/test_owner.py
@@ -22,11 +22,6 @@
 # tests.  They're not exactly integration tests, but they do touch lots of
 # parts of the system.
 
-__all__ = [
-    'TestEmailToOwner',
-    ]
-
-
 import unittest
 
 from mailman.app.lifecycle import create_list
@@ -44,7 +39,6 @@ from operator import itemgetter
 from zope.component import getUtility
 
 
-
 class TestEmailToOwner(unittest.TestCase):
     """Test emailing a mailing list's -owner address."""
 
diff --git a/src/mailman/runners/tests/test_pipeline.py b/src/mailman/runners/tests/test_pipeline.py
index f8dcfc507..14f13883d 100644
--- a/src/mailman/runners/tests/test_pipeline.py
+++ b/src/mailman/runners/tests/test_pipeline.py
@@ -17,11 +17,6 @@
 
 """Test the pipeline runner."""
 
-__all__ = [
-    'TestPipelineRunner',
-    ]
-
-
 import unittest
 
 from mailman.app.lifecycle import create_list
@@ -35,7 +30,6 @@ from mailman.testing.layers import ConfigLayer
 from zope.interface import implementer
 
 
-
 @implementer(IHandler)
 class MyTestHandler:
     """See `IHandler`."""
@@ -51,7 +45,6 @@ class MyTestHandler:
         self._test.mark(self._marker)
 
 
-
 @implementer(IPipeline)
 class MyTestPipeline:
     name = 'test'
@@ -65,7 +58,6 @@ class MyTestPipeline:
         yield MyTestHandler(self._marker, self._test)
 
 
-
 class TestPipelineRunner(unittest.TestCase):
     """Test the pipeline runner."""
 
diff --git a/src/mailman/runners/tests/test_rest.py b/src/mailman/runners/tests/test_rest.py
index 958908c3a..99e4dad02 100644
--- a/src/mailman/runners/tests/test_rest.py
+++ b/src/mailman/runners/tests/test_rest.py
@@ -17,11 +17,6 @@
 
 """Test the REST runner."""
 
-__all__ = [
-    'TestRESTRunner',
-    ]
-
-
 import os
 import signal
 import unittest
@@ -30,7 +25,6 @@ from mailman.testing.helpers import call_api, wait_for_webservice
 from mailman.testing.layers import RESTLayer
 
 
-
 class TestRESTRunner(unittest.TestCase):
     """Test the REST runner."""
 
diff --git a/src/mailman/runners/tests/test_retry.py b/src/mailman/runners/tests/test_retry.py
index 8d17fa276..739dd78c7 100644
--- a/src/mailman/runners/tests/test_retry.py
+++ b/src/mailman/runners/tests/test_retry.py
@@ -17,11 +17,6 @@
 
 """Test the retry runner."""
 
-__all__ = [
-    'TestRetryRunner',
-    ]
-
-
 import unittest
 
 from mailman.app.lifecycle import create_list
@@ -33,7 +28,6 @@ from mailman.testing.helpers import (
 from mailman.testing.layers import ConfigLayer
 
 
-
 class TestRetryRunner(unittest.TestCase):
     """Test the retry runner."""
 
@@ -55,4 +49,4 @@ Message-Id: <first>
     def test_message_put_in_outgoing_queue(self):
         self._retryq.enqueue(self._msg, self._msgdata)
         self._runner.run()
-        self.assertEqual(len(get_queue_messages('out')), 1)
+        get_queue_messages('out', expected_count=1)
diff --git a/src/mailman/runners/virgin.py b/src/mailman/runners/virgin.py
index 4172f04e4..a69d07bf7 100644
--- a/src/mailman/runners/virgin.py
+++ b/src/mailman/runners/virgin.py
@@ -23,16 +23,12 @@ to go through some minimal processing before they can be sent out to the
 recipient.
 """
 
-__all__ = [
-    'VirginRunner',
-    ]
-
-
+from mailman import public
 from mailman.core.pipelines import process
 from mailman.core.runner import Runner
 
 
-
+@public
 class VirginRunner(Runner):
     def _dispose(self, mlist, msg, msgdata):
         # We need to fast track this message through any pipeline handlers