Move todays_booths_for_officer to the model

This way we can easily add a test which will fail if by accident we
change the method to use `Date.today`. Until now using `Date.today`
would only fail if we ran specs in a time zone with a different date.

app/controllers/officing/base_controller.rb

@@ -28,7 +28,7 @@ class Officing::BaseController < ApplicationController
 
     def verify_booth
       return unless current_booth.blank?
-      booths = todays_booths_for_officer(current_user.poll_officer)
+      booths = current_user.poll_officer.todays_booths
       case booths.count
       when 0
         redirect_to officing_root_path
@@ -43,8 +43,4 @@ class Officing::BaseController < ApplicationController
       Poll::Booth.where(id: session[:booth_id]).first
     end
 
-    def todays_booths_for_officer(officer)
-      officer.officer_assignments.by_date(Date.today).map(&:booth).uniq
-    end
-
 end

app/controllers/officing/booth_controller.rb

@@ -3,7 +3,7 @@ class Officing::BoothController < Officing::BaseController
   before_action :verify_officer_assignment
 
   def new
-    @booths = todays_booths_for_officer(current_user.poll_officer)
+    @booths = current_user.poll_officer.todays_booths
   end
 
   def create

app/models/poll/officer.rb

@@ -23,5 +23,9 @@ class Poll
                                sort {|x, y| y.ends_at <=> x.ends_at}
     end
 
+    def todays_booths
+      officer_assignments.by_date(Date.current).map(&:booth).uniq
+    end
+
   end
 end