test that CAP LS 301 responses are only one line

[slingamn]

Can confirm that all four of these assertions are currently broken in Ergo's master; the proximate cause is ergochat/ergo#2065 , the root cause is, well, Ergo's willingness to emit an incorrect response.

[progval]

Suggested change

	@cases.mark_specifications("IRCv3")
	def testNoMultiline301Response(self):
	"""
	Current version: "If the client supports CAP version 302, the server MAY send
	multiple lines in response to CAP LS and CAP LIST." This should be read as
	disallowing multiline responses to pre-302 clients.
	-- <https://ircv3.net/specs/extensions/capability-negotiation#multiline-replies-to-cap-ls-and-cap-list>
	""" # noqa
	self.check301ResponsePreRegistration("bar")
	self.check301ResponsePreRegistration("qux", "CAP LS 301")
	self.check301ResponsePostRegistration("baz")
	self.check301ResponsePostRegistration("bat", "CAP LS 301")
	def check301ResponsePreRegistration(self, nick, cap_ls="CAP LS"):
	self.addClient(nick)
	self.sendLine(nick, cap_ls)
	self.sendLine(nick, "NICK " + nick)
	self.sendLine(nick, "USER u s e r")
	self.sendLine(nick, "CAP END")
	responses = [msg for msg in self.skipToWelcome(nick) if msg.command == "CAP"]
	self.assertLessEqual(len(responses), 1, responses)
	def check301ResponsePostRegistration(self, nick, cap_ls="CAP LS"):
	self.connectClient(nick, name=nick)
	self.sendLine(nick, cap_ls)
	responses = [msg for msg in self.getMessages(nick) if msg.command == "CAP"]
	self.assertLessEqual(len(responses), 1, responses)
	@cases.mark_specifications("IRCv3")
	def testNoMultiline301Response(self):
	"""
	Current version: "If the client supports CAP version 302, the server MAY send
	multiple lines in response to CAP LS and CAP LIST." This should be read as
	disallowing multiline responses to pre-302 clients.
	-- <https://ircv3.net/specs/extensions/capability-negotiation#multiline-replies-to-cap-ls-and-cap-list>
	""" # noqa
	self.check301ResponsePreRegistration("bar", "CAP LS")
	self.check301ResponsePreRegistration("qux", "CAP LS 301")
	self.check301ResponsePostRegistration("baz", "CAP LS")
	self.check301ResponsePostRegistration("bat", "CAP LS 301")
	def check301ResponsePreRegistration(self, nick, cap_ls):
	self.addClient(nick)
	self.sendLine(nick, cap_ls)
	self.sendLine(nick, "NICK " + nick)
	self.sendLine(nick, "USER u s e r")
	self.sendLine(nick, "CAP END")
	responses = [msg for msg in self.skipToWelcome(nick) if msg.command == "CAP"]
	self.assertLessEqual(len(responses), 1, responses)
	def check301ResponsePostRegistration(self, nick, cap_ls):
	self.connectClient(nick, name=nick)
	self.sendLine(nick, cap_ls)
	responses = [msg for msg in self.getMessages(nick) if msg.command == "CAP"]
	self.assertLessEqual(len(responses), 1, responses)