diff --git a/app/controllers/concerns/creates_ticket_articles.rb b/app/controllers/concerns/creates_ticket_articles.rb
index 1569a7436..82a2001dc 100644
--- a/app/controllers/concerns/creates_ticket_articles.rb
+++ b/app/controllers/concerns/creates_ticket_articles.rb
@@ -36,7 +36,7 @@ module CreatesTicketArticles
       clean_params.delete(:sender)
       clean_params.delete(:origin_by_id)
       type = Ticket::Article::Type.lookup(id: clean_params[:type_id])
-      if type.name !~ /^(note|web)$/
+      unless type.name.match?(/^(note|web)$/)
         clean_params[:type_id] = Ticket::Article::Type.lookup(name: 'note').id
       end
       clean_params.delete(:type)
@@ -89,7 +89,7 @@ module CreatesTicketArticles
           preferences[store_key] = attachment[key]
         end
 
-        if attachment[:data] !~ %r{^([A-Za-z0-9+/]{4})*([A-Za-z0-9+/]{4}|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)$}
+        unless attachment[:data].match?(%r{^([A-Za-z0-9+/]{4})*([A-Za-z0-9+/]{4}|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)$})
           raise Exceptions::UnprocessableEntity, "Invalid base64 for attachment with index '#{index}'"
         end
 
diff --git a/app/controllers/form_controller.rb b/app/controllers/form_controller.rb
index d0a535ddf..832419d2e 100644
--- a/app/controllers/form_controller.rb
+++ b/app/controllers/form_controller.rb
@@ -43,7 +43,7 @@ class FormController < ApplicationController
     end
     if params[:email].blank?
       errors['email'] = 'required'
-    elsif params[:email] !~ /@/
+    elsif !/@/.match?(params[:email])
       errors['email'] = 'invalid'
     elsif params[:email].match?(/(>|<|\||\!|"|§|'|\$|%|&|\(|\)|\?|\s|\.\.)/)
       errors['email'] = 'invalid'
@@ -67,7 +67,7 @@ class FormController < ApplicationController
         Rails.logger.info "Can't verify email #{params[:email]}: #{message}"
 
         # ignore 450, graylistings
-        if message !~ /450/
+        unless message.match?(/450/)
           errors['email'] = message
         end
       end
diff --git a/app/controllers/import_zendesk_controller.rb b/app/controllers/import_zendesk_controller.rb
index 11d24cf2e..c9ed0758d 100644
--- a/app/controllers/import_zendesk_controller.rb
+++ b/app/controllers/import_zendesk_controller.rb
@@ -39,7 +39,7 @@ class ImportZendeskController < ApplicationController
     end
 
     # since 2016-10-15 a redirect to a marketing page has been implemented
-    if response.body !~ /#{params[:url]}/
+    unless response.body.match?(/#{params[:url]}/)
       render json: {
         result: 'invalid',
         message_human: 'Hostname not found!',
diff --git a/app/controllers/settings_controller.rb b/app/controllers/settings_controller.rb
index 6d332edb0..bb14774ce 100644
--- a/app/controllers/settings_controller.rb
+++ b/app/controllers/settings_controller.rb
@@ -45,7 +45,7 @@ class SettingsController < ApplicationController
     end
 
     # validate image
-    if clean_params[:logo] !~ /^data:image/i
+    unless clean_params[:logo].match?(/^data:image/i)
       render json: {
         result: 'invalid',
         message: 'Invalid payload, need data:image in logo param',
diff --git a/app/models/channel/driver/pop3.rb b/app/models/channel/driver/pop3.rb
index 549a678d9..64cba4d1d 100644
--- a/app/models/channel/driver/pop3.rb
+++ b/app/models/channel/driver/pop3.rb
@@ -91,7 +91,7 @@ returns
         next if !mail
 
         # check how many content messages we have, for notice used
-        if mail !~ /x-zammad-ignore/i
+        unless mail.match?(/x-zammad-ignore/i)
           content_messages += 1
           break if content_max_check < content_messages
         end
diff --git a/app/models/channel/filter/identify_sender.rb b/app/models/channel/filter/identify_sender.rb
index e1c0955f2..d5e722b16 100644
--- a/app/models/channel/filter/identify_sender.rb
+++ b/app/models/channel/filter/identify_sender.rb
@@ -144,7 +144,7 @@ module Channel::Filter::IdentifySender
   end
 
   def self.user_create(data, role_ids = nil)
-    if data[:email] !~ /@/
+    unless data[:email].match?(/@/)
       data[:email] += '@local'
     end
     user = User.find_by(email: data[:email].downcase)
diff --git a/app/models/history.rb b/app/models/history.rb
index 15fae7bc8..149668af2 100644
--- a/app/models/history.rb
+++ b/app/models/history.rb
@@ -4,8 +4,6 @@ class History < ApplicationModel
   include History::Assets
 
   self.table_name = 'histories'
-
-  # rubocop:disable Rails/InverseOf
   belongs_to :history_type,      class_name: 'History::Type'
   belongs_to :history_object,    class_name: 'History::Object'
   belongs_to :history_attribute, class_name: 'History::Attribute'
diff --git a/app/models/link.rb b/app/models/link.rb
index 0361ce474..5ac666184 100644
--- a/app/models/link.rb
+++ b/app/models/link.rb
@@ -1,8 +1,6 @@
 # Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
 
 class Link < ApplicationModel
-
-  # rubocop:disable Rails/InverseOf
   belongs_to :link_type,   class_name: 'Link::Type'
   belongs_to :link_object, class_name: 'Link::Object'
   # rubocop:enable Rails/InverseOf
diff --git a/app/models/object_manager/attribute.rb b/app/models/object_manager/attribute.rb
index bccea00cf..1d7129e44 100644
--- a/app/models/object_manager/attribute.rb
+++ b/app/models/object_manager/attribute.rb
@@ -756,7 +756,7 @@ to send no browser reload event, pass false
     if !data_type
       raise 'Need data_type param'
     end
-    if data_type !~ /^(input|user_autocompletion|checkbox|select|tree_select|datetime|date|tag|richtext|textarea|integer|autocompletion_ajax|boolean|user_permission|active)$/
+    unless data_type.match?(/^(input|user_autocompletion|checkbox|select|tree_select|datetime|date|tag|richtext|textarea|integer|autocompletion_ajax|boolean|user_permission|active)$/)
       raise "Invalid data_type param '#{data_type}'"
     end
 
diff --git a/app/models/organization.rb b/app/models/organization.rb
index 3c2f8c45a..d168cb156 100644
--- a/app/models/organization.rb
+++ b/app/models/organization.rb
@@ -12,8 +12,6 @@ class Organization < ApplicationModel
   include Organization::Assets
   include Organization::Search
   include Organization::SearchIndex
-
-  # rubocop:disable Rails/InverseOf
   has_many :members, class_name: 'User'
   # rubocop:enable Rails/InverseOf
 
diff --git a/app/models/store.rb b/app/models/store.rb
index 0a3d78ead..b8c09758e 100644
--- a/app/models/store.rb
+++ b/app/models/store.rb
@@ -4,7 +4,6 @@ require_dependency 'store/object'
 require_dependency 'store/file'
 
 class Store < ApplicationModel
-  # rubocop:disable Rails/InverseOf
   belongs_to :store_object, class_name: 'Store::Object'
   belongs_to :store_file,   class_name: 'Store::File'
   # rubocop:enable Rails/InverseOf
diff --git a/app/models/tag.rb b/app/models/tag.rb
index 8410b2aa3..9de2e3b66 100644
--- a/app/models/tag.rb
+++ b/app/models/tag.rb
@@ -1,8 +1,6 @@
 # Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
 
 class Tag < ApplicationModel
-
-  # rubocop:disable Rails/InverseOf
   belongs_to :tag_object, class_name: 'Tag::Object'
   belongs_to :tag_item,   class_name: 'Tag::Item'
   # rubocop:enable Rails/InverseOf
diff --git a/app/models/ticket.rb b/app/models/ticket.rb
index f71bc5300..decdd40ca 100644
--- a/app/models/ticket.rb
+++ b/app/models/ticket.rb
@@ -57,8 +57,6 @@ class Ticket < ApplicationModel
   belongs_to    :organization
   has_many      :articles,               class_name: 'Ticket::Article', after_add: :cache_update, after_remove: :cache_update, dependent: :destroy, inverse_of: :ticket
   has_many      :ticket_time_accounting, class_name: 'Ticket::TimeAccounting', dependent: :destroy, inverse_of: :ticket
-
-  # rubocop:disable Rails/InverseOf
   belongs_to    :state,                 class_name: 'Ticket::State'
   belongs_to    :priority,              class_name: 'Ticket::Priority'
   belongs_to    :owner,                 class_name: 'User'
diff --git a/app/models/ticket/article.rb b/app/models/ticket/article.rb
index a6442bc1d..acaed55f0 100644
--- a/app/models/ticket/article.rb
+++ b/app/models/ticket/article.rb
@@ -11,8 +11,6 @@ class Ticket::Article < ApplicationModel
 
   belongs_to :ticket
   has_one    :ticket_time_accounting, class_name: 'Ticket::TimeAccounting', foreign_key: :ticket_article_id, dependent: :destroy, inverse_of: :ticket_article
-
-  # rubocop:disable Rails/InverseOf
   belongs_to :type,       class_name: 'Ticket::Article::Type'
   belongs_to :sender,     class_name: 'Ticket::Article::Sender'
   belongs_to :created_by, class_name: 'User'
diff --git a/app/models/ticket/state.rb b/app/models/ticket/state.rb
index 6b126269b..680710e2d 100644
--- a/app/models/ticket/state.rb
+++ b/app/models/ticket/state.rb
@@ -3,7 +3,6 @@ class Ticket::State < ApplicationModel
   include ChecksLatestChangeObserved
 
   belongs_to :state_type, class_name: 'Ticket::StateType', inverse_of: :states
-  # rubocop:disable Rails/InverseOf
   belongs_to :next_state, class_name: 'Ticket::State'
   # rubocop:enable Rails/InverseOf
 
diff --git a/lib/html_sanitizer.rb b/lib/html_sanitizer.rb
index 3fc361c69..9cc444a3d 100644
--- a/lib/html_sanitizer.rb
+++ b/lib/html_sanitizer.rb
@@ -134,7 +134,7 @@ satinize html string based on whiltelist
         value = node[key]
         node.delete(key)
         next if value.blank?
-        if value !~ /%|px|em/i
+        unless value.match?(/%|px|em/i)
           value += 'px'
         end
         node['style'] += "#{key}:#{value}"
diff --git a/lib/version.rb b/lib/version.rb
index c1cbbc853..7fd5c736f 100644
--- a/lib/version.rb
+++ b/lib/version.rb
@@ -18,6 +18,6 @@ returns
     File.read(Rails.root.join('VERSION')).strip
   rescue => e
     Rails.logger.error "VERSION file could not be read: #{e}"
-    return ''
+    ''
   end
 end
diff --git a/test/browser/agent_ticket_tag_test.rb b/test/browser/agent_ticket_tag_test.rb
index 1d881b5e7..7abcd0c64 100644
--- a/test/browser/agent_ticket_tag_test.rb
+++ b/test/browser/agent_ticket_tag_test.rb
@@ -37,7 +37,7 @@ class AgentTicketTagTest < TestCase
       css: '.active .newTicket button.js-submit',
     )
     sleep 5
-    if @browser.current_url !~ /#{Regexp.quote('#ticket/zoom/')}/
+    unless @browser.current_url.match?(/#{Regexp.quote('#ticket/zoom/')}/)
       raise 'Unable to create ticket!'
     end
 
@@ -69,7 +69,7 @@ class AgentTicketTagTest < TestCase
     click(css: '#global-search')
     click(css: '.active .newTicket button.js-submit')
     sleep 5
-    if @browser.current_url !~ /#{Regexp.quote('#ticket/zoom/')}/
+    unless @browser.current_url.match?(/#{Regexp.quote('#ticket/zoom/')}/)
       raise 'Unable to create ticket!'
     end
 
@@ -428,7 +428,7 @@ class AgentTicketTagTest < TestCase
       css: '.active .newTicket button.js-submit',
     )
     sleep 5
-    if @browser.current_url !~ /#{Regexp.quote('#ticket/zoom/')}/
+    unless @browser.current_url.match?(/#{Regexp.quote('#ticket/zoom/')}/)
       raise 'Unable to create ticket!'
     end
 
diff --git a/test/browser_test_helper.rb b/test/browser_test_helper.rb
index 44fa08113..ef158a54a 100644
--- a/test/browser_test_helper.rb
+++ b/test/browser_test_helper.rb
@@ -104,7 +104,7 @@ class TestCase < Test::Unit::TestCase
     browser_width = ENV['BROWSER_WIDTH'] || 1024
     browser_height = ENV['BROWSER_HEIGHT'] || 800
     local_browser.manage.window.resize_to(browser_width, browser_height)
-    if ENV['REMOTE_URL'] !~ /saucelabs|(grid|ci)\.(zammad\.org|znuny\.com)/i
+    unless ENV['REMOTE_URL'].match?(/saucelabs|(grid|ci)\.(zammad\.org|znuny\.com)/i)
       if @browsers.count == 1
         local_browser.manage.window.move_to(0, 0)
       else
@@ -362,7 +362,7 @@ class TestCase < Test::Unit::TestCase
     instance = params[:browser] || @browser
     sleep 0.7
     current_url = instance.current_url
-    if current_url !~ /#{Regexp.quote(params[:url])}/
+    unless current_url.match?(/#{Regexp.quote(params[:url])}/)
       screenshot(browser: instance, comment: 'location_check_failed')
       raise "url #{current_url} is not matching #{params[:url]}"
     end
@@ -1352,7 +1352,7 @@ wait untill text in selector disabppears
       if params[:value]
         begin
           text = instance.find_elements(css: params[:css])[0].text
-          if text !~ /#{params[:value]}/i
+          unless text.match?(/#{params[:value]}/i)
             assert(true, "not matching '#{params[:value]}' in text '#{text}'")
             sleep 1
             return true
@@ -2427,7 +2427,7 @@ wait untill text in selector disabppears
     element.click
     sleep 1
     number = instance.find_elements(css: '.content.active .ticketZoom-header .ticket-number')[0].text
-    if number !~ /#{params[:number]}/
+    unless number.match?(/#{params[:number]}/)
       screenshot(browser: instance, comment: 'ticket_open_by_overview_open_failed_failed')
       raise "unable to open ticket #{params[:number]}!"
     end
@@ -2473,7 +2473,7 @@ wait untill text in selector disabppears
     instance.execute_script("$(\".js-global-search-result a:contains('#{params[:number]}') .nav-tab-icon\").first().click()")
     sleep 1
     number = instance.find_elements(css: '.content.active .ticketZoom-header .ticket-number')[0].text
-    if number !~ /#{params[:number]}/
+    unless number.match?(/#{params[:number]}/)
       screenshot(browser: instance, comment: 'ticket_open_by_search_failed')
       raise "unable to search/find ticket #{params[:number]}!"
     end
@@ -2509,7 +2509,7 @@ wait untill text in selector disabppears
     instance.execute_script("$(\".js-global-search-result a:contains('#{params[:title]}') .nav-tab-icon\").click()")
     sleep 1
     title = instance.find_elements(css: '.content.active .ticketZoom-header .js-objectTitle')[0].text
-    if title !~ /#{params[:title]}/
+    unless title.match?(/#{params[:title]}/)
       screenshot(browser: instance, comment: 'ticket_open_by_title_failed')
       raise "unable to search/find ticket #{params[:title]}!"
     end
@@ -2597,7 +2597,7 @@ wait untill text in selector disabppears
     instance.execute_script("$(\".js-global-search-result a:contains('#{params[:value]}') .nav-tab-icon\").click()")
     sleep 1
     name = instance.find_elements(css: '.content.active h1')[0].text
-    if name !~ /#{params[:value]}/
+    unless name.match?(/#{params[:value]}/)
       screenshot(browser: instance, comment: 'organization_open_by_search_failed')
       raise "unable to search/find org #{params[:value]}!"
     end
@@ -2632,7 +2632,7 @@ wait untill text in selector disabppears
     instance.execute_script("$(\".js-global-search-result a:contains('#{params[:value]}') .nav-tab-icon\").click()")
     sleep 1
     name = instance.find_elements(css: '.content.active h1')[0].text
-    if name !~ /#{params[:value]}/
+    unless name.match?(/#{params[:value]}/)
       screenshot(browser: instance, comment: 'user_open_by_search_failed')
       raise "unable to search/find user #{params[:value]}!"
     end