diff --git a/irctest/server_tests/test_resume.py b/irctest/server_tests/test_resume.py
index 907b1b4..99bf9e6 100644
--- a/irctest/server_tests/test_resume.py
+++ b/irctest/server_tests/test_resume.py
@@ -4,6 +4,9 @@
 
 from irctest import cases
 
+from irctest.numerics import RPL_AWAY
+
+ANCIENT_TIMESTAMP = '2006-01-02T15:04:05.999Z'
 
 class ResumeTestCase(cases.BaseServerTestCase):
 
@@ -19,7 +22,7 @@ class ResumeTestCase(cases.BaseServerTestCase):
         self.connectClient('bar', capabilities=['batch', 'draft/labeled-response', 'server-time'])
         ms = self.getMessages(1)
 
-        welcome = self.connectClient('baz', capabilities=['batch', 'draft/labeled-response', 'server-time', 'draft/resume-0.3'])
+        welcome = self.connectClient('baz', capabilities=['batch', 'draft/labeled-response', 'server-time', 'draft/resume-0.4'])
         resume_messages = [m for m in welcome if m.command == 'RESUME']
         self.assertEqual(len(resume_messages), 1)
         self.assertEqual(resume_messages[0].params[0], 'TOKEN')
@@ -43,14 +46,14 @@ class ResumeTestCase(cases.BaseServerTestCase):
         bad_token = 'a' * len(token)
         self.addClient()
         self.sendLine(3, 'CAP LS')
-        self.sendLine(3, 'CAP REQ :batch draft/labeled-response server-time draft/resume-0.3')
+        self.sendLine(3, 'CAP REQ :batch draft/labeled-response server-time draft/resume-0.4')
         self.sendLine(3, 'NICK tempnick')
         self.sendLine(3, 'USER tempuser 0 * tempuser')
-        self.sendLine(3, 'RESUME ' + bad_token + ' 2006-01-02T15:04:05.999Z')
+        self.sendLine(3, ' '.join(('RESUME', bad_token, ANCIENT_TIMESTAMP)))
 
         # resume with a bad token MUST fail
         ms = self.getMessages(3)
-        resume_err_messages = [m for m in ms if m.command == 'RESUME' and m.params[0] == 'ERR']
+        resume_err_messages = [m for m in ms if m.command == 'FAIL' and m.params[:2] == ['RESUME', 'INVALID_TOKEN']]
         self.assertEqual(len(resume_err_messages), 1)
         # however, registration should proceed with the alternative nick
         self.sendLine(3, 'CAP END')
@@ -59,20 +62,22 @@ class ResumeTestCase(cases.BaseServerTestCase):
 
         self.addClient()
         self.sendLine(4, 'CAP LS')
-        self.sendLine(4, 'CAP REQ :batch draft/labeled-response server-time draft/resume-0.3')
+        self.sendLine(4, 'CAP REQ :batch draft/labeled-response server-time draft/resume-0.4')
         self.sendLine(4, 'NICK tempnick_')
         self.sendLine(4, 'USER tempuser 0 * tempuser')
         # resume with a timestamp in the distant past
-        self.sendLine(4, 'RESUME ' + token + ' 2006-01-02T15:04:05.999Z')
+        self.sendLine(4, ' '.join(('RESUME', token, ANCIENT_TIMESTAMP)))
         # successful resume does not require CAP END:
         # https://github.com/ircv3/ircv3-specifications/pull/306/files#r255318883
         ms = self.getMessages(4)
 
+        # now, do a valid resume with the correct token
         resume_messages = [m for m in ms if m.command == 'RESUME']
         self.assertEqual(len(resume_messages), 2)
         self.assertEqual(resume_messages[0].params[0], 'TOKEN')
         new_token = resume_messages[0].params[1]
         self.assertNotEqual(token, new_token, 'should receive a new, strong resume token; instead got ' + new_token)
+        # success message
         self.assertMessageEqual(resume_messages[1], command='RESUME', params=['SUCCESS', 'baz'])
 
         # test replay of messages
@@ -86,9 +91,77 @@ class ResumeTestCase(cases.BaseServerTestCase):
         # hence will typically match by accident
         self.assertEqual(privmsgs[0].tags.get('time'), channelMsgTime)
 
+        # legacy client should receive a QUIT and a JOIN
+        quit, join = [m for m in self.getMessages(1) if m.command in ('QUIT', 'JOIN')]
+        self.assertEqual(quit.command, 'QUIT')
+        self.assertTrue(quit.prefix.startswith('baz'))
+        self.assertMessageEqual(join, command='JOIN', params=['#xyz'])
+        self.assertTrue(join.prefix.startswith('baz'))
+
         # original client should have been disconnected
         self.assertDisconnected(2)
         # new client should be receiving PRIVMSG sent to baz
         self.sendLine(1, 'PRIVMSG baz :hello again')
         self.getMessages(1)
         self.assertMessageEqual(self.getMessage(4), command='PRIVMSG', params=['baz', 'hello again'])
+
+        # test chain-resuming (resuming the resumed connection, using the new token)
+        self.addClient()
+        self.sendLine(5, 'CAP LS')
+        self.sendLine(5, 'CAP REQ :batch draft/labeled-response server-time draft/resume-0.4')
+        self.sendLine(5, 'NICK tempnick_')
+        self.sendLine(5, 'USER tempuser 0 * tempuser')
+        self.sendLine(5, 'RESUME ' + new_token)
+        ms = self.getMessages(5)
+
+        resume_messages = [m for m in ms if m.command == 'RESUME']
+        self.assertEqual(len(resume_messages), 2)
+        self.assertEqual(resume_messages[0].params[0], 'TOKEN')
+        new_new_token = resume_messages[0].params[1]
+        self.assertNotEqual(token, new_new_token, 'should receive a new, strong resume token; instead got ' + new_new_token)
+        self.assertNotEqual(new_token, new_new_token, 'should receive a new, strong resume token; instead got ' + new_new_token)
+        # success message
+        self.assertMessageEqual(resume_messages[1], command='RESUME', params=['SUCCESS', 'baz'])
+
+
+    @cases.SpecificationSelector.requiredBySpecification('Oragono')
+    def testBRB(self):
+        self.connectClient('bar', capabilities=['batch', 'draft/labeled-response', 'message-tags', 'server-time'])
+        ms = self.getMessages(1)
+        self.joinChannel(1, '#xyz')
+
+        welcome = self.connectClient('baz', capabilities=['batch', 'draft/labeled-response', 'server-time', 'draft/resume-0.4'])
+        resume_messages = [m for m in welcome if m.command == 'RESUME']
+        self.assertEqual(len(resume_messages), 1)
+        self.assertEqual(resume_messages[0].params[0], 'TOKEN')
+        token = resume_messages[0].params[1]
+        self.joinChannel(2, '#xyz')
+
+        self.getMessages(1)
+        self.sendLine(2, 'BRB :software upgrade')
+        # should receive, e.g., `BRB 210` (number of seconds)
+        ms = [m for m in self.getMessages(2) if m.command == 'BRB']
+        self.assertEqual(len(ms), 1)
+        self.assertGreater(int(ms[0].params[0]), 1)
+        # BRB disconnects you
+        self.assertDisconnected(2)
+        # without sending a QUIT line to friends
+        self.assertEqual(self.getMessages(1), [])
+
+        self.sendLine(1, 'PRIVMSG baz :hey there')
+        # BRB message should be sent as an away message
+        self.assertMessageEqual(self.getMessage(1), command=RPL_AWAY, params=['bar', 'baz', 'software upgrade'])
+
+        self.addClient(3)
+        self.sendLine(3, 'CAP REQ :batch account-tag message-tags draft/resume-0.4')
+        self.sendLine(3, ' '.join(('RESUME', token, ANCIENT_TIMESTAMP)))
+        ms = self.getMessages(3)
+
+        resume_messages = [m for m in ms if m.command == 'RESUME']
+        self.assertEqual(len(resume_messages), 2)
+        self.assertEqual(resume_messages[0].params[0], 'TOKEN')
+        self.assertMessageEqual(resume_messages[1], command='RESUME', params=['SUCCESS', 'baz'])
+
+        privmsgs = [m for m in ms if m.command == 'PRIVMSG' and m.prefix.startswith('bar')]
+        self.assertEqual(len(privmsgs), 1)
+        self.assertMessageEqual(privmsgs[0], params=['baz', 'hey there'])