Rails Testing controller methods that all have instance variables set in before filters

Rails Testing controller methods that all have instance variables set in
before filters

Ok, so my main issue is I have implemented Mailboxer into our project to
handle messaging and I am trying to write tests for it. However, I keep
stumbling over and over again. I have attempted several different
stub/mocks but have made no progress.
We have a conversations_controller.rb that relies on before_filters for
setting all the instance variables necessary for doing each action. Then
in the controller actions, the instance variables are referenced directly
to do any sort of action or to return specific data.
Here is an example of our index action which returns all conversations in
the "box" that is specified in the before_filter, of the mailbox also
specified in another before_filter:
class ConversationsController < ::ApplicationController
before_filter :get_user_mailbox, only: [:index, :new_message,
:show_message, :mark_as_read, :mark_as_unread, :create_message,
:reply_message, :update, :destroy_message, :untrash]
before_filter :get_box
def index
if @box.eql? "inbox"
@conversations = @mailbox.inbox
elsif @box.eql? "sentbox"
@conversations = @mailbox.sentbox
else
@conversations = @mailbox.trash
end
end
And before filters:
private
def get_user_mailbox
@user = User.where(:user_name => user.user_name.downcase).where(:email
=> user.email.downcase).first_or_create
@mailbox = @user.mailbox if @user
end
def get_box
if params[:box].blank? or
!["inbox","sentbox","trash"].include?params[:box]
params[:box] = 'inbox'
end
@box = params[:box]
end
So I guess I have 2 questions in one. First, how to I get my tests to
generate the correct data @mailbox, @user, and @box that is needed for the
index action. Next, how do I pass the fake parameter to set @box to
different "inbox/sentbox/trash". I have tried controller.index({box:
"inbox"}) but always get "wrong arguments 1 for 0" messages.