Split all the e2e tests in their own files

Some duplication is avoided, but most importantly: it’s much much cleaner,
easier to find, functions have been cleaned up (functools.partial usages are
now hidden), etc.

tests/end_to_end/scenarios/simple_channel_join.py

@@ -0,0 +1,22 @@
+from scenarios import *
+
+def expect_self_join_presence(jid, chan, nick, irc_server="{irc_server_one}"):
+    return (
+    expect_stanza("/message/body[text()='Mode " + chan + " [+nt] by irc.localhost']"),
+    expect_stanza("/presence[@to='" + jid +"'][@from='" + chan + "%" + irc_server + "/" + nick + "']/muc_user:x/muc_user:item[@affiliation='admin'][@role='moderator']",
+                  "/presence/muc_user:x/muc_user:status[@code='100']", # Rooms are all non-anonymous
+                  "/presence/muc_user:x/muc_user:status[@code='110']",
+                  ),
+    expect_stanza("/message[@from='" + chan + "%" + irc_server + "'][@type='groupchat']/subject[not(text())]"),
+    )
+
+
+scenario = (
+    sequences.handshake(),
+    send_stanza("<presence from='{jid_one}/{resource_one}' to='#foo%{irc_server_one}/{nick_one}' />"),
+    sequences.connection(),
+
+    expect_self_join_presence(jid = '{jid_one}/{resource_one}', chan = "#foo", nick = "{nick_one}"),
+
+)
+