diff --git a/actioncable/lib/action_cable/engine.rb b/actioncable/lib/action_cable/engine.rb
index e23527b84e..63a26636a0 100644
--- a/actioncable/lib/action_cable/engine.rb
+++ b/actioncable/lib/action_cable/engine.rb
@@ -31,7 +31,7 @@ module ActionCable
           self.cable = Rails.application.config_for(config_path).with_indifferent_access
         end
 
-        previous_connection_class = self.connection_class
+        previous_connection_class = connection_class
         self.connection_class = -> { "ApplicationCable::Connection".safe_constantize || previous_connection_class.call }
 
         options.each { |k, v| send("#{k}=", v) }
diff --git a/actioncable/lib/rails/generators/channel/channel_generator.rb b/actioncable/lib/rails/generators/channel/channel_generator.rb
index 04b787c3a4..984b78bc9c 100644
--- a/actioncable/lib/rails/generators/channel/channel_generator.rb
+++ b/actioncable/lib/rails/generators/channel/channel_generator.rb
@@ -13,7 +13,7 @@ module Rails
         template "channel.rb", File.join("app/channels", class_path, "#{file_name}_channel.rb")
 
         if options[:assets]
-          if self.behavior == :invoke
+          if behavior == :invoke
             template "assets/cable.js", "app/assets/javascripts/cable.js"
           end
 
@@ -30,7 +30,7 @@ module Rails
 
         # FIXME: Change these files to symlinks once RubyGems 2.5.0 is required.
         def generate_application_cable_files
-          return if self.behavior != :invoke
+          return if behavior != :invoke
 
           files = [
             "application_cable/channel.rb",
diff --git a/actionmailer/lib/action_mailer/delivery_methods.rb b/actionmailer/lib/action_mailer/delivery_methods.rb
index be98f4c65e..bcc4ef03cf 100644
--- a/actionmailer/lib/action_mailer/delivery_methods.rb
+++ b/actionmailer/lib/action_mailer/delivery_methods.rb
@@ -59,7 +59,7 @@ module ActionMailer
       end
 
       def wrap_delivery_behavior(mail, method = nil, options = nil) # :nodoc:
-        method ||= self.delivery_method
+        method ||= delivery_method
         mail.delivery_handler = self
 
         case method
diff --git a/actionmailer/lib/action_mailer/preview.rb b/actionmailer/lib/action_mailer/preview.rb
index c147ca78d0..b0152aff03 100644
--- a/actionmailer/lib/action_mailer/preview.rb
+++ b/actionmailer/lib/action_mailer/preview.rb
@@ -63,7 +63,7 @@ module ActionMailer
       # interceptors will be informed so that they can transform the message
       # as they would if the mail was actually being delivered.
       def call(email)
-        preview = self.new
+        preview = new
         message = preview.public_send(email)
         inform_preview_interceptors(message)
         message
diff --git a/actionmailer/lib/action_mailer/test_case.rb b/actionmailer/lib/action_mailer/test_case.rb
index ebc7b37961..cbd841466d 100644
--- a/actionmailer/lib/action_mailer/test_case.rb
+++ b/actionmailer/lib/action_mailer/test_case.rb
@@ -57,7 +57,7 @@ module ActionMailer
         end
 
         def mailer_class
-          if mailer = self._mailer_class
+          if mailer = _mailer_class
             mailer
           else
             tests determine_default_mailer(name)
diff --git a/actionmailer/lib/rails/generators/mailer/mailer_generator.rb b/actionmailer/lib/rails/generators/mailer/mailer_generator.rb
index 4a8d0178de..99fe4544f1 100644
--- a/actionmailer/lib/rails/generators/mailer/mailer_generator.rb
+++ b/actionmailer/lib/rails/generators/mailer/mailer_generator.rb
@@ -11,7 +11,7 @@ module Rails
         template "mailer.rb", File.join("app/mailers", class_path, "#{file_name}_mailer.rb")
 
         in_root do
-          if self.behavior == :invoke && !File.exist?(application_mailer_file_name)
+          if behavior == :invoke && !File.exist?(application_mailer_file_name)
             template "application_mailer.rb", application_mailer_file_name
           end
         end
diff --git a/actionpack/lib/action_controller/metal/head.rb b/actionpack/lib/action_controller/metal/head.rb
index 4dff23dd85..0c50894bce 100644
--- a/actionpack/lib/action_controller/metal/head.rb
+++ b/actionpack/lib/action_controller/metal/head.rb
@@ -37,7 +37,7 @@ module ActionController
 
       if include_content?(response_code)
         self.content_type = content_type || (Mime[formats.first] if formats)
-        self.response.charset = false
+        response.charset = false
       end
 
       true
diff --git a/actionpack/lib/action_controller/metal/rendering.rb b/actionpack/lib/action_controller/metal/rendering.rb
index 4c01891d4c..6b17719381 100644
--- a/actionpack/lib/action_controller/metal/rendering.rb
+++ b/actionpack/lib/action_controller/metal/rendering.rb
@@ -114,7 +114,7 @@ module ActionController
 
         self.status = status if status
         self.content_type = content_type if content_type
-        self.headers["Location"] = url_for(location) if location
+        headers["Location"] = url_for(location) if location
 
         super
       end
diff --git a/actionpack/lib/action_controller/metal/strong_parameters.rb b/actionpack/lib/action_controller/metal/strong_parameters.rb
index acfeca1fcb..6e8df02fb9 100644
--- a/actionpack/lib/action_controller/metal/strong_parameters.rb
+++ b/actionpack/lib/action_controller/metal/strong_parameters.rb
@@ -150,7 +150,7 @@ module ActionController
     # permitted flag.
     def ==(other)
       if other.respond_to?(:permitted?)
-        self.permitted? == other.permitted? && self.parameters == other.parameters
+        permitted? == other.permitted? && parameters == other.parameters
       else
         @parameters == other
       end
diff --git a/actionpack/lib/action_controller/test_case.rb b/actionpack/lib/action_controller/test_case.rb
index 441667e556..7b620ac95e 100644
--- a/actionpack/lib/action_controller/test_case.rb
+++ b/actionpack/lib/action_controller/test_case.rb
@@ -354,7 +354,7 @@ module ActionController
         end
 
         def controller_class
-          if current_controller_class = self._controller_class
+          if current_controller_class = _controller_class
             current_controller_class
           else
             self.controller_class = determine_default_controller_class(name)
diff --git a/actionpack/test/controller/integration_test.rb b/actionpack/test/controller/integration_test.rb
index 4fae4071b1..cd1415b56c 100644
--- a/actionpack/test/controller/integration_test.rb
+++ b/actionpack/test/controller/integration_test.rb
@@ -269,8 +269,8 @@ class IntegrationProcessTest < ActionDispatch::IntegrationTest
 
   test "response cookies are added to the cookie jar for the next request" do
     with_test_route_set do
-      self.cookies["cookie_1"] = "sugar"
-      self.cookies["cookie_2"] = "oatmeal"
+      cookies["cookie_1"] = "sugar"
+      cookies["cookie_2"] = "oatmeal"
       get "/cookie_monster"
       assert_equal "cookie_1=; path=/\ncookie_3=chocolate; path=/", headers["Set-Cookie"]
       assert_equal({ "cookie_1" => "", "cookie_2" => "oatmeal", "cookie_3" => "chocolate" }, cookies.to_hash)
diff --git a/actionpack/test/controller/url_for_test.rb b/actionpack/test/controller/url_for_test.rb
index 382b4e273d..862dcf01c3 100644
--- a/actionpack/test/controller/url_for_test.rb
+++ b/actionpack/test/controller/url_for_test.rb
@@ -26,7 +26,7 @@ module AbstractController
                                              action: :index
             }
           }.url_helpers
-          self.default_url_options[:host] = "example.com"
+          default_url_options[:host] = "example.com"
         }
 
         path = klass.new.fun_path(controller: :articles,
diff --git a/actionpack/test/dispatch/routing_test.rb b/actionpack/test/dispatch/routing_test.rb
index 474d053af6..53758a4fbc 100644
--- a/actionpack/test/dispatch/routing_test.rb
+++ b/actionpack/test/dispatch/routing_test.rb
@@ -1603,7 +1603,7 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
       get "account/login", to: redirect("/login")
     end
 
-    previous_host, self.host = self.host, "www.example.com:3000"
+    previous_host, self.host = host, "www.example.com:3000"
 
     get "/account/login"
     verify_redirect "http://www.example.com:3000/login"
diff --git a/actionview/lib/action_view/helpers/tags/date_select.rb b/actionview/lib/action_view/helpers/tags/date_select.rb
index 006605885a..638c134deb 100644
--- a/actionview/lib/action_view/helpers/tags/date_select.rb
+++ b/actionview/lib/action_view/helpers/tags/date_select.rb
@@ -16,7 +16,7 @@ module ActionView
 
         class << self
           def select_type
-            @select_type ||= self.name.split("::").last.sub("Select", "").downcase
+            @select_type ||= name.split("::").last.sub("Select", "").downcase
           end
         end
 
diff --git a/actionview/lib/action_view/helpers/tags/text_field.rb b/actionview/lib/action_view/helpers/tags/text_field.rb
index 4306c3543d..613cade7b3 100644
--- a/actionview/lib/action_view/helpers/tags/text_field.rb
+++ b/actionview/lib/action_view/helpers/tags/text_field.rb
@@ -17,7 +17,7 @@ module ActionView
 
         class << self
           def field_type
-            @field_type ||= self.name.split("::").last.sub("Field", "").downcase
+            @field_type ||= name.split("::").last.sub("Field", "").downcase
           end
         end
 
diff --git a/actionview/lib/action_view/layouts.rb b/actionview/lib/action_view/layouts.rb
index 18e395a67f..81feb90486 100644
--- a/actionview/lib/action_view/layouts.rb
+++ b/actionview/lib/action_view/layouts.rb
@@ -319,7 +319,7 @@ module ActionView
             name_clause
           end
 
-        self.class_eval <<-RUBY, __FILE__, __LINE__ + 1
+        class_eval <<-RUBY, __FILE__, __LINE__ + 1
           def _layout(formats)
             if _conditional_layout?
               #{layout_definition}
diff --git a/actionview/lib/action_view/test_case.rb b/actionview/lib/action_view/test_case.rb
index 5fb7bb54b5..2b981caa65 100644
--- a/actionview/lib/action_view/test_case.rb
+++ b/actionview/lib/action_view/test_case.rb
@@ -206,8 +206,8 @@ module ActionView
           view = @controller.view_context
           view.singleton_class.include(_helpers)
           view.extend(Locals)
-          view.rendered_views = self.rendered_views
-          view.output_buffer = self.output_buffer
+          view.rendered_views = rendered_views
+          view.output_buffer = output_buffer
           view
         end
       end
diff --git a/actionview/lib/action_view/view_paths.rb b/actionview/lib/action_view/view_paths.rb
index a9638d1e6d..f0fe6831fa 100644
--- a/actionview/lib/action_view/view_paths.rb
+++ b/actionview/lib/action_view/view_paths.rb
@@ -5,7 +5,7 @@ module ActionView
     included do
       class_attribute :_view_paths
       self._view_paths = ActionView::PathSet.new
-      self._view_paths.freeze
+      _view_paths.freeze
     end
 
     delegate :template_exists?, :any_templates?, :view_paths, :formats, :formats=,
diff --git a/actionview/test/activerecord/polymorphic_routes_test.rb b/actionview/test/activerecord/polymorphic_routes_test.rb
index 8495949975..fb670e5dbe 100644
--- a/actionview/test/activerecord/polymorphic_routes_test.rb
+++ b/actionview/test/activerecord/polymorphic_routes_test.rb
@@ -61,7 +61,7 @@ end
 
 class PolymorphicRoutesTest < ActionController::TestCase
   include SharedTestRoutes.url_helpers
-  self.default_url_options[:host] = "example.com"
+  default_url_options[:host] = "example.com"
 
   def setup
     @project = Project.new
diff --git a/activejob/lib/rails/generators/job/job_generator.rb b/activejob/lib/rails/generators/job/job_generator.rb
index 97c11a9ea6..50476a2e50 100644
--- a/activejob/lib/rails/generators/job/job_generator.rb
+++ b/activejob/lib/rails/generators/job/job_generator.rb
@@ -19,7 +19,7 @@ module Rails # :nodoc:
         template "job.rb", File.join("app/jobs", class_path, "#{file_name}_job.rb")
 
         in_root do
-          if self.behavior == :invoke && !File.exist?(application_job_file_name)
+          if behavior == :invoke && !File.exist?(application_job_file_name)
             template "application_job.rb", application_job_file_name
           end
         end
diff --git a/activejob/test/cases/queue_naming_test.rb b/activejob/test/cases/queue_naming_test.rb
index 0e1e0decd1..0247bc111e 100644
--- a/activejob/test/cases/queue_naming_test.rb
+++ b/activejob/test/cases/queue_naming_test.rb
@@ -56,7 +56,7 @@ class QueueNamingTest < ActiveSupport::TestCase
     original_queue_name = HelloJob.queue_name
 
     begin
-      HelloJob.queue_as { self.arguments.first == "1" ? :one : :two }
+      HelloJob.queue_as { arguments.first == "1" ? :one : :two }
       assert_equal "one", HelloJob.new("1").queue_name
       assert_equal "two", HelloJob.new("3").queue_name
     ensure
diff --git a/activejob/test/cases/queue_priority_test.rb b/activejob/test/cases/queue_priority_test.rb
index b0d0e903fc..171fb1e593 100644
--- a/activejob/test/cases/queue_priority_test.rb
+++ b/activejob/test/cases/queue_priority_test.rb
@@ -32,7 +32,7 @@ class QueuePriorityTest < ActiveSupport::TestCase
     original_priority = HelloJob.priority
 
     begin
-      HelloJob.queue_with_priority { self.arguments.first == "1" ? 99 : 11 }
+      HelloJob.queue_with_priority { arguments.first == "1" ? 99 : 11 }
       assert_equal 99, HelloJob.new("1").priority
       assert_equal 11, HelloJob.new("3").priority
     ensure
diff --git a/activejob/test/support/sneakers/inline.rb b/activejob/test/support/sneakers/inline.rb
index 3cdc54e6d5..cf102ae5c2 100644
--- a/activejob/test/support/sneakers/inline.rb
+++ b/activejob/test/support/sneakers/inline.rb
@@ -4,7 +4,7 @@ module Sneakers
   module Worker
     module ClassMethods
       def enqueue(msg)
-        worker = self.new(nil, nil, {})
+        worker = new(nil, nil, {})
         worker.work(*msg)
       end
     end
diff --git a/activemodel/lib/active_model/naming.rb b/activemodel/lib/active_model/naming.rb
index 9532c63b65..9853cf38fe 100644
--- a/activemodel/lib/active_model/naming.rb
+++ b/activemodel/lib/active_model/naming.rb
@@ -234,7 +234,7 @@ module ActiveModel
     #   Person.model_name.plural   # => "people"
     def model_name
       @_model_name ||= begin
-        namespace = self.parents.detect do |n|
+        namespace = parents.detect do |n|
           n.respond_to?(:use_relative_model_naming?) && n.use_relative_model_naming?
         end
         ActiveModel::Name.new(self, namespace)
diff --git a/activemodel/lib/active_model/translation.rb b/activemodel/lib/active_model/translation.rb
index b8cf43cc10..35fc7cf743 100644
--- a/activemodel/lib/active_model/translation.rb
+++ b/activemodel/lib/active_model/translation.rb
@@ -44,7 +44,7 @@ module ActiveModel
       parts     = attribute.to_s.split(".")
       attribute = parts.pop
       namespace = parts.join("/") unless parts.empty?
-      attributes_scope = "#{self.i18n_scope}.attributes"
+      attributes_scope = "#{i18n_scope}.attributes"
 
       if namespace
         defaults = lookup_ancestors.map do |klass|
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index c05a6c87df..f3e2189bcb 100644
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1857,7 +1857,7 @@ module ActiveRecord
           end
 
           has_many name, scope, hm_options, &extension
-          self._reflections[name.to_s].parent_reflection = habtm_reflection
+          _reflections[name.to_s].parent_reflection = habtm_reflection
         end
       end
   end
diff --git a/activerecord/lib/active_record/associations/has_many_association.rb b/activerecord/lib/active_record/associations/has_many_association.rb
index 25613d2fa7..b413eb3f9c 100644
--- a/activerecord/lib/active_record/associations/has_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_association.rb
@@ -100,7 +100,7 @@ module ActiveRecord
         end
 
         def delete_or_nullify_all_records(method)
-          count = delete_count(method, self.scope)
+          count = delete_count(method, scope)
           update_counter(-count)
         end
 
diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index 8fcac82a0d..2f32caa257 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -9,7 +9,7 @@ module ActiveRecord
       # available.
       def to_key
         sync_with_transaction_state
-        key = self.id
+        key = id
         [key] if key
       end
 
diff --git a/activerecord/lib/active_record/autosave_association.rb b/activerecord/lib/active_record/autosave_association.rb
index 9d0b501862..6bccbc06cd 100644
--- a/activerecord/lib/active_record/autosave_association.rb
+++ b/activerecord/lib/active_record/autosave_association.rb
@@ -328,9 +328,9 @@ module ActiveRecord
       def association_valid?(reflection, record, index = nil)
         return true if record.destroyed? || (reflection.options[:autosave] && record.marked_for_destruction?)
 
-        validation_context = self.validation_context unless [:create, :update].include?(self.validation_context)
+        context = validation_context unless [:create, :update].include?(validation_context)
 
-        unless valid = record.valid?(validation_context)
+        unless valid = record.valid?(context)
           if reflection.options[:autosave]
             indexed_attribute = !index.nil? && (reflection.options[:index_errors] || ActiveRecord::Base.index_nested_attribute_errors)
 
diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index 6d2361c4ac..4d30bdf196 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -450,7 +450,7 @@ module ActiveRecord
     #   [ Person.find(1), Person.find(2), Person.find(3) ] & [ Person.find(1), Person.find(4) ] # => [ Person.find(1) ]
     def hash
       if id
-        self.class.hash ^ self.id.hash
+        self.class.hash ^ id.hash
       else
         super
       end
@@ -472,7 +472,7 @@ module ActiveRecord
     # Allows sort on objects
     def <=>(other_object)
       if other_object.is_a?(self.class)
-        self.to_key <=> other_object.to_key
+        to_key <=> other_object.to_key
       else
         super
       end
diff --git a/activerecord/lib/active_record/fixtures.rb b/activerecord/lib/active_record/fixtures.rb
index de1b0d63bc..91d8054ef2 100644
--- a/activerecord/lib/active_record/fixtures.rb
+++ b/activerecord/lib/active_record/fixtures.rb
@@ -885,7 +885,7 @@ module ActiveRecord
       #
       # The keys must be the fixture names, that coincide with the short paths to the fixture files.
       def set_fixture_class(class_names = {})
-        self.fixture_class_names = self.fixture_class_names.merge(class_names.stringify_keys)
+        self.fixture_class_names = fixture_class_names.merge(class_names.stringify_keys)
       end
 
       def fixtures(*fixture_set_names)
diff --git a/activerecord/lib/active_record/nested_attributes.rb b/activerecord/lib/active_record/nested_attributes.rb
index e983026961..01ecd79b8f 100644
--- a/activerecord/lib/active_record/nested_attributes.rb
+++ b/activerecord/lib/active_record/nested_attributes.rb
@@ -393,7 +393,7 @@ module ActiveRecord
       # update_only is true, and a <tt>:_destroy</tt> key set to a truthy value,
       # then the existing record will be marked for destruction.
       def assign_nested_attributes_for_one_to_one_association(association_name, attributes)
-        options = self.nested_attributes_options[association_name]
+        options = nested_attributes_options[association_name]
         if attributes.respond_to?(:permitted?)
           attributes = attributes.to_h
         end
@@ -452,7 +452,7 @@ module ActiveRecord
       #     { id: '2', _destroy: true }
       #   ])
       def assign_nested_attributes_for_collection_association(association_name, attributes_collection)
-        options = self.nested_attributes_options[association_name]
+        options = nested_attributes_options[association_name]
         if attributes_collection.respond_to?(:permitted?)
           attributes_collection = attributes_collection.to_h
         end
@@ -562,7 +562,7 @@ module ActiveRecord
       def call_reject_if(association_name, attributes)
         return false if will_be_destroyed?(association_name, attributes)
 
-        case callback = self.nested_attributes_options[association_name][:reject_if]
+        case callback = nested_attributes_options[association_name][:reject_if]
         when Symbol
           method(callback).arity == 0 ? send(callback) : send(callback, attributes)
         when Proc
diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index 2701c5bca9..0276d41494 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -87,8 +87,8 @@ module ActiveRecord
             if File.file?(filename)
               cache = YAML.load(File.read(filename))
               if cache.version == ActiveRecord::Migrator.current_version
-                self.connection.schema_cache = cache
-                self.connection_pool.schema_cache = cache.dup
+                connection.schema_cache = cache
+                connection_pool.schema_cache = cache.dup
               else
                 warn "Ignoring db/schema_cache.yml because it has expired. The current schema version is #{ActiveRecord::Migrator.current_version}, but the one in the cache is #{cache.version}."
               end
diff --git a/activerecord/lib/active_record/readonly_attributes.rb b/activerecord/lib/active_record/readonly_attributes.rb
index 8ff265bdfa..6274996ab8 100644
--- a/activerecord/lib/active_record/readonly_attributes.rb
+++ b/activerecord/lib/active_record/readonly_attributes.rb
@@ -11,7 +11,7 @@ module ActiveRecord
       # Attributes listed as readonly will be used to create a new record but update operations will
       # ignore these fields.
       def attr_readonly(*attributes)
-        self._attr_readonly = Set.new(attributes.map(&:to_s)) + (self._attr_readonly || [])
+        self._attr_readonly = Set.new(attributes.map(&:to_s)) + (_attr_readonly || [])
       end
 
       # Returns an array of all the attributes that have been specified as readonly.
diff --git a/activerecord/lib/active_record/relation/batches.rb b/activerecord/lib/active_record/relation/batches.rb
index 4b2987ac6d..76031515fd 100644
--- a/activerecord/lib/active_record/relation/batches.rb
+++ b/activerecord/lib/active_record/relation/batches.rb
@@ -260,7 +260,7 @@ module ActiveRecord
       end
 
       def act_on_ignored_order(error_on_ignore)
-        raise_error = (error_on_ignore.nil? ? self.klass.error_on_ignored_order : error_on_ignore)
+        raise_error = (error_on_ignore.nil? ? klass.error_on_ignored_order : error_on_ignore)
 
         if raise_error
           raise ArgumentError.new(ORDER_IGNORE_MESSAGE)
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index 827688a663..35c670f1a1 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -193,7 +193,7 @@ module ActiveRecord
 
         # If #count is used with #distinct (i.e. `relation.distinct.count`) it is
         # considered distinct.
-        distinct = self.distinct_value
+        distinct = distinct_value
 
         if operation == "count"
           column_name ||= select_for_count
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index 8cad57200a..4ee413c805 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -656,7 +656,7 @@ module ActiveRecord
       end
 
       self.where_clause = self.where_clause.or(other.where_clause)
-      self.having_clause = self.having_clause.or(other.having_clause)
+      self.having_clause = having_clause.or(other.having_clause)
 
       self
     end
diff --git a/activerecord/lib/active_record/sanitization.rb b/activerecord/lib/active_record/sanitization.rb
index 647834b12e..427c0019c6 100644
--- a/activerecord/lib/active_record/sanitization.rb
+++ b/activerecord/lib/active_record/sanitization.rb
@@ -46,7 +46,7 @@ module ActiveRecord
         #
         #   sanitize_sql_for_assignment("name=NULL and group_id='4'")
         #   # => "name=NULL and group_id='4'"
-        def sanitize_sql_for_assignment(assignments, default_table_name = self.table_name) # :doc:
+        def sanitize_sql_for_assignment(assignments, default_table_name = table_name) # :doc:
           case assignments
           when Array; sanitize_sql_array(assignments)
           when Hash;  sanitize_sql_hash_for_assignment(assignments, default_table_name)
diff --git a/activerecord/lib/active_record/secure_token.rb b/activerecord/lib/active_record/secure_token.rb
index 7606961e2e..115799cc20 100644
--- a/activerecord/lib/active_record/secure_token.rb
+++ b/activerecord/lib/active_record/secure_token.rb
@@ -27,7 +27,7 @@ module ActiveRecord
         # Load securerandom only when has_secure_token is used.
         require "active_support/core_ext/securerandom"
         define_method("regenerate_#{attribute}") { update! attribute => self.class.generate_unique_secure_token }
-        before_create { self.send("#{attribute}=", self.class.generate_unique_secure_token) unless self.send("#{attribute}?") }
+        before_create { send("#{attribute}=", self.class.generate_unique_secure_token) unless send("#{attribute}?") }
       end
 
       def generate_unique_secure_token
diff --git a/activerecord/lib/rails/generators/active_record/model/model_generator.rb b/activerecord/lib/rails/generators/active_record/model/model_generator.rb
index 61a8d3c100..a9df5212e3 100644
--- a/activerecord/lib/rails/generators/active_record/model/model_generator.rb
+++ b/activerecord/lib/rails/generators/active_record/model/model_generator.rb
@@ -41,7 +41,7 @@ module ActiveRecord
 
         # FIXME: Change this file to a symlink once RubyGems 2.5.0 is required.
         def generate_application_record
-          if self.behavior == :invoke && !application_record_exist?
+          if behavior == :invoke && !application_record_exist?
             template "application_record.rb", application_record_file_name
           end
         end
diff --git a/activerecord/test/cases/autosave_association_test.rb b/activerecord/test/cases/autosave_association_test.rb
index 6d31b7a091..2203aa1788 100644
--- a/activerecord/test/cases/autosave_association_test.rb
+++ b/activerecord/test/cases/autosave_association_test.rb
@@ -37,7 +37,7 @@ class TestAutosaveAssociationsInGeneral < ActiveRecord::TestCase
       private
 
         def should_be_cool
-          unless self.first_name == "cool"
+          unless first_name == "cool"
             errors.add :first_name, "not cool"
           end
         end
diff --git a/activerecord/test/cases/callbacks_test.rb b/activerecord/test/cases/callbacks_test.rb
index 11ec6fb2c5..53ff037de1 100644
--- a/activerecord/test/cases/callbacks_test.rb
+++ b/activerecord/test/cases/callbacks_test.rb
@@ -125,11 +125,11 @@ class ContextualCallbacksDeveloper < ActiveRecord::Base
   after_validation :after_validation_on_create_and_update, on: [ :create, :update ]
 
   def before_validation_on_create_and_update
-    history << "before_validation_on_#{self.validation_context}".to_sym
+    history << "before_validation_on_#{validation_context}".to_sym
   end
 
   def after_validation_on_create_and_update
-    history << "after_validation_on_#{self.validation_context}".to_sym
+    history << "after_validation_on_#{validation_context}".to_sym
   end
 
   def history
diff --git a/activerecord/test/cases/fixtures_test.rb b/activerecord/test/cases/fixtures_test.rb
index 1381678eef..61e596e208 100644
--- a/activerecord/test/cases/fixtures_test.rb
+++ b/activerecord/test/cases/fixtures_test.rb
@@ -1012,7 +1012,7 @@ end
 
 class FixtureClassNamesTest < ActiveRecord::TestCase
   def setup
-    @saved_cache = self.fixture_class_names.dup
+    @saved_cache = fixture_class_names.dup
   end
 
   def teardown
diff --git a/activerecord/test/cases/locking_test.rb b/activerecord/test/cases/locking_test.rb
index 95fb670dac..9e42242e55 100644
--- a/activerecord/test/cases/locking_test.rb
+++ b/activerecord/test/cases/locking_test.rb
@@ -18,7 +18,7 @@ class LockWithoutDefault < ActiveRecord::Base; end
 
 class LockWithCustomColumnWithoutDefault < ActiveRecord::Base
   self.table_name = :lock_without_defaults_cust
-  self.column_defaults # to test @column_defaults caching.
+  column_defaults # to test @column_defaults caching.
   self.locking_column = :custom_lock_version
 end
 
diff --git a/activerecord/test/cases/relation/mutation_test.rb b/activerecord/test/cases/relation/mutation_test.rb
index 2cbbc775ce..de15eb9187 100644
--- a/activerecord/test/cases/relation/mutation_test.rb
+++ b/activerecord/test/cases/relation/mutation_test.rb
@@ -108,7 +108,7 @@ module ActiveRecord
     end
 
     test "#reorder!" do
-      @relation = self.relation.order("foo")
+      @relation = relation.order("foo")
 
       assert relation.reorder!("bar").equal?(relation)
       assert_equal ["bar"], relation.order_values
diff --git a/activerecord/test/cases/timestamp_test.rb b/activerecord/test/cases/timestamp_test.rb
index 7766a74612..39b40e3411 100644
--- a/activerecord/test/cases/timestamp_test.rb
+++ b/activerecord/test/cases/timestamp_test.rb
@@ -422,7 +422,7 @@ class TimestampTest < ActiveRecord::TestCase
       self.table_name = "people"
 
       before_create do
-        self.born_at = self.created_at
+        self.born_at = created_at
       end
     end
 
diff --git a/activerecord/test/models/customer.rb b/activerecord/test/models/customer.rb
index 60af7c2247..3d40cb1ace 100644
--- a/activerecord/test/models/customer.rb
+++ b/activerecord/test/models/customer.rb
@@ -56,7 +56,7 @@ class GpsLocation
   end
 
   def ==(other)
-    self.latitude == other.latitude && self.longitude == other.longitude
+    latitude == other.latitude && longitude == other.longitude
   end
 end
 
diff --git a/activesupport/lib/active_support/core_ext/array/grouping.rb b/activesupport/lib/active_support/core_ext/array/grouping.rb
index ea9d85f6e3..0d798e5c4e 100644
--- a/activesupport/lib/active_support/core_ext/array/grouping.rb
+++ b/activesupport/lib/active_support/core_ext/array/grouping.rb
@@ -89,7 +89,7 @@ class Array
   #   [1, 2, 3, 4, 5].split(3)              # => [[1, 2], [4, 5]]
   #   (1..10).to_a.split { |i| i % 3 == 0 } # => [[1, 2], [4, 5], [7, 8], [10]]
   def split(value = nil)
-    arr = self.dup
+    arr = dup
     result = []
     if block_given?
       while (idx = arr.index { |i| yield i })
diff --git a/activesupport/lib/active_support/core_ext/date/calculations.rb b/activesupport/lib/active_support/core_ext/date/calculations.rb
index 2e64097933..d6f60cac04 100644
--- a/activesupport/lib/active_support/core_ext/date/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date/calculations.rb
@@ -133,7 +133,7 @@ class Date
   # Allow Date to be compared with Time by converting to DateTime and relying on the <=> from there.
   def compare_with_coercion(other)
     if other.is_a?(Time)
-      self.to_datetime <=> other
+      to_datetime <=> other
     else
       compare_without_coercion(other)
     end
diff --git a/activesupport/lib/active_support/testing/isolation.rb b/activesupport/lib/active_support/testing/isolation.rb
index 14edd13a8f..54c3263efa 100644
--- a/activesupport/lib/active_support/testing/isolation.rb
+++ b/activesupport/lib/active_support/testing/isolation.rb
@@ -43,7 +43,7 @@ module ActiveSupport
                   end
                 }
               end
-              result = Marshal.dump(self.dup)
+              result = Marshal.dump(dup)
             end
 
             write.puts [result].pack("m")
@@ -78,7 +78,7 @@ module ActiveSupport
                 "ISOLATION_OUTPUT" => tmpfile.path
               }
 
-              test_opts = "-n#{self.class.name}##{self.name}"
+              test_opts = "-n#{self.class.name}##{name}"
 
               load_path_args = []
               $-I.each do |p|
diff --git a/activesupport/lib/active_support/xml_mini/libxmlsax.rb b/activesupport/lib/active_support/xml_mini/libxmlsax.rb
index 4edb0bd2b1..8a43b05b17 100644
--- a/activesupport/lib/active_support/xml_mini/libxmlsax.rb
+++ b/activesupport/lib/active_support/xml_mini/libxmlsax.rb
@@ -73,7 +73,7 @@ module ActiveSupport
 
         LibXML::XML::Error.set_handler(&LibXML::XML::Error::QUIET_HANDLER)
         parser = LibXML::XML::SaxParser.io(data)
-        document = self.document_class.new
+        document = document_class.new
 
         parser.callbacks = document
         parser.parse
diff --git a/activesupport/lib/active_support/xml_mini/nokogirisax.rb b/activesupport/lib/active_support/xml_mini/nokogirisax.rb
index b8b85146c5..7388bea5d8 100644
--- a/activesupport/lib/active_support/xml_mini/nokogirisax.rb
+++ b/activesupport/lib/active_support/xml_mini/nokogirisax.rb
@@ -76,7 +76,7 @@ module ActiveSupport
         {}
       else
         data.ungetc(char)
-        document = self.document_class.new
+        document = document_class.new
         parser = Nokogiri::XML::SAX::Parser.new(document)
         parser.parse(data)
         document.hash
diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index 59020333ba..0226c0ffe5 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -131,7 +131,7 @@ module Rails
 
       def colorize_logging=(val)
         ActiveSupport::LogSubscriber.colorize_logging = val
-        self.generators.colorize_logging = val
+        generators.colorize_logging = val
       end
 
       def session_store(new_session_store = nil, **options)
diff --git a/railties/lib/rails/engine.rb b/railties/lib/rails/engine.rb
index 2dd1fb3273..12b4f06c27 100644
--- a/railties/lib/rails/engine.rb
+++ b/railties/lib/rails/engine.rb
@@ -380,7 +380,7 @@ module Rails
       def isolate_namespace(mod)
         engine_name(generate_railtie_name(mod.name))
 
-        self.routes.default_scope = { module: ActiveSupport::Inflector.underscore(mod.name) }
+        routes.default_scope = { module: ActiveSupport::Inflector.underscore(mod.name) }
         self.isolated = true
 
         unless mod.respond_to?(:railtie_namespace)
@@ -573,7 +573,7 @@ module Rails
     end
 
     initializer :add_routing_paths do |app|
-      routing_paths = self.paths["config/routes.rb"].existent
+      routing_paths = paths["config/routes.rb"].existent
 
       if routes? || routing_paths.any?
         app.routes_reloader.paths.unshift(*routing_paths)
diff --git a/railties/lib/rails/generators/actions.rb b/railties/lib/rails/generators/actions.rb
index d058d82cea..0bd0615b7e 100644
--- a/railties/lib/rails/generators/actions.rb
+++ b/railties/lib/rails/generators/actions.rb
@@ -269,7 +269,7 @@ module Rails
           if args.size == 1
             say args.first.to_s unless options.quiet?
           else
-            args << (self.behavior == :invoke ? :green : :red)
+            args << (behavior == :invoke ? :green : :red)
             say_status(*args)
           end
         end
diff --git a/railties/lib/rails/generators/base.rb b/railties/lib/rails/generators/base.rb
index cc6ae3860f..ba031d7b5d 100644
--- a/railties/lib/rails/generators/base.rb
+++ b/railties/lib/rails/generators/base.rb
@@ -331,7 +331,7 @@ module Rails
         def self.prepare_for_invocation(name, value) #:nodoc:
           return super unless value.is_a?(String) || value.is_a?(Symbol)
 
-          if value && constants = self.hooks[name]
+          if value && constants = hooks[name]
             value = name if TrueClass === value
             Rails::Generators.find_by_namespace(value, *constants)
           elsif klass = Rails::Generators.find_by_namespace(value)
diff --git a/railties/lib/rails/generators/erb/mailer/mailer_generator.rb b/railties/lib/rails/generators/erb/mailer/mailer_generator.rb
index 677f8041ae..d74b5655d5 100644
--- a/railties/lib/rails/generators/erb/mailer/mailer_generator.rb
+++ b/railties/lib/rails/generators/erb/mailer/mailer_generator.rb
@@ -9,7 +9,7 @@ module Erb # :nodoc:
         view_base_path = File.join("app/views", class_path, file_name + "_mailer")
         empty_directory view_base_path
 
-        if self.behavior == :invoke
+        if behavior == :invoke
           formats.each do |format|
             layout_path = File.join("app/views/layouts", class_path, filename_with_extensions("mailer", format))
             template filename_with_extensions(:layout, format), layout_path
diff --git a/railties/lib/rails/generators/migration.rb b/railties/lib/rails/generators/migration.rb
index 0d63b9a5c9..82481169c3 100644
--- a/railties/lib/rails/generators/migration.rb
+++ b/railties/lib/rails/generators/migration.rb
@@ -35,7 +35,7 @@ module Rails
       end
 
       def set_migration_assigns!(destination)
-        destination = File.expand_path(destination, self.destination_root)
+        destination = File.expand_path(destination, destination_root)
 
         migration_dir = File.dirname(destination)
         @migration_number     = self.class.next_migration_number(migration_dir)
diff --git a/railties/lib/rails/generators/named_base.rb b/railties/lib/rails/generators/named_base.rb
index e3660b012a..6f1925928b 100644
--- a/railties/lib/rails/generators/named_base.rb
+++ b/railties/lib/rails/generators/named_base.rb
@@ -219,7 +219,7 @@ module Rails
         #
         def self.check_class_collision(options = {}) # :doc:
           define_method :check_class_collision do
-            name = if self.respond_to?(:controller_class_name) # for ScaffoldBase
+            name = if respond_to?(:controller_class_name) # for ScaffoldBase
               controller_class_name
             else
               class_name
diff --git a/railties/lib/rails/test_help.rb b/railties/lib/rails/test_help.rb
index db341dd847..5fda160012 100644
--- a/railties/lib/rails/test_help.rb
+++ b/railties/lib/rails/test_help.rb
@@ -17,7 +17,7 @@ if defined?(ActiveRecord::Base)
   class ActiveSupport::TestCase
     include ActiveRecord::TestFixtures
     self.fixture_path = "#{Rails.root}/test/fixtures/"
-    self.file_fixture_path = self.fixture_path + "files"
+    self.file_fixture_path = fixture_path + "files"
   end
 
   ActionDispatch::IntegrationTest.fixture_path = ActiveSupport::TestCase.fixture_path