Followup b5147a4634
When we aliased `leave` to `remove` and renamed
the method in `DirectMessageChannel` in the previous
commit, this inadvertantly caused an error when
unfollowing group channels in the channel list.
When clicking the X in the channel list, we hit
ChannelsCurrentUserMembershipFollowsController for the
current user and the channel, which is supposed to only
unfollow the channel for all channel types including DMs.
Group DMs have a different Leave behaviour vs Unfollow.
Leaving the channel altogether is done from the channel
settings page, the "Leave channel" button, and that
deletes the user's membership and DM user record from that
channel.
So, we were trying to do the leave channel behaviour in the
unfollow channel controller, which was returning the wrong
record for the serializer (a User not a Membership)
This fixes the issue and removes a bit of delegate/alias indirection
which was making the code a bit harder to fllow and search, even
though it was more succinct. Also adds missing specs that would
have caught this regression.
e92e05b22e
