Use boolean comparators where it makes sense

plugins/messages/app/controllers/messages_controller.rb

@@ -10,7 +10,7 @@ class MessagesController < ApplicationController
   # Creates a new message object.
   def new
     @message = Message.new(params[:message])
-    if @message.reply_to and not @message.reply_to.is_readable_for?(current_user)
+    if @message.reply_to && !@message.reply_to.is_readable_for?(current_user)
       redirect_to new_message_url, alert: 'Nachricht ist privat!'
     end
   end

plugins/messages/lib/foodsoft_messages/user_link.rb

@@ -6,7 +6,7 @@ module FoodsoftMessages
 
         # modify user presentation link to writing a message for the user
         def show_user_link(user=@current_user)
-          if user.nil? or not FoodsoftMessages.enabled?
+          if user.nil? || !FoodsoftMessages.enabled?
             show_user user
           else
             link_to show_user(user), new_message_path('message[mail_to]' => user.id),

plugins/uservoice/lib/foodsoft_uservoice.rb

@@ -4,7 +4,7 @@ require "foodsoft_uservoice/engine"
 module FoodsoftUservoice
   # enabled when configured, but can still be disabled by use_uservoice option
   def self.enabled?
-    FoodsoftConfig[:use_uservoice] != false and FoodsoftConfig[:uservoice]
+    FoodsoftConfig[:use_uservoice] != false && FoodsoftConfig[:uservoice]
   end
 
   module LoadUservoice

plugins/wiki/app/controllers/pages_controller.rb

@@ -84,7 +84,7 @@ class PagesController < ApplicationController
     else
       if @page.save
         @page.parent_id = parent_id if (!params[:parent_id].blank? \
-            and params[:parent_id] != @page_id)
+            && params[:parent_id] != @page_id)
         flash[:notice] = I18n.t('pages.update.notice')
         redirect_to wiki_page_path(@page.permalink)
       else

plugins/wiki/app/helpers/pages_helper.rb

@@ -62,7 +62,7 @@ module PagesHelper
 
   def parent_pages_to_select(current_page)
     unless current_page.homepage? # Homepage is the page trees root!
-      Page.non_redirected.reject { |p| p == current_page or p.ancestors.include?(current_page) }
+      Page.non_redirected.reject { |p| p == current_page || p.ancestors.include?(current_page) }
     else
       Array.new
     end

plugins/wiki/app/views/pages/_body.html.haml

@@ -1,7 +1,7 @@
 - content = wikified_body @page.body, @page.title
 - toc = generate_toc @page.body
 
-- unless toc.blank? or params[:preview]
+- unless toc.blank? || params[:preview]
   - content_for :sidebar do
     #wikitoc.well.well-small
       %h3= t '.title_toc'