Merge branch 'master' into bug/filtered_parameters_class

62 files changed, 511 insertions, 268 deletions

diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index cc908dcc43..d3d3188d95 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,4 +1,37 @@
-*  Add `action_controller_api` and `action_controller_base` load hooks to be called in `ActiveSupport.on_load`
+*   `driven_by` now registers poltergeist and capybara-webkit
+
+    If driver poltergeist or capybara-webkit is set for System Tests,
+    `driven_by` will register the driver and set additional options passed via
+    `:options` param.
+
+    Refer to drivers documentation to learn what options can be passed.
+
+    *Mario Chavez*
+
+*   AEAD encrypted cookies and sessions with GCM
+
+    Encrypted cookies now use AES-GCM which couples authentication and
+    encryption in one faster step and produces shorter ciphertexts. Cookies
+    encrypted using AES in CBC HMAC mode will be seamlessly upgraded when
+    this new mode is enabled via the
+    `action_dispatch.use_authenticated_cookie_encryption` configuration value.
+
+    *Michael J Coyne*
+
+*   Change the cache key format for fragments to make it easier to debug key churn. The new format is:
+
+        views/template/action.html.erb:7a1156131a6928cb0026877f8b749ac9/projects/123
+              ^template path           ^template tree digest            ^class   ^id
+
+    *DHH*
+
+*   Add support for recyclable cache keys with fragment caching. This uses the new versioned entries in the
+    `ActiveSupport::Cache` stores and relies on the fact that Active Record has split `#cache_key` and `#cache_version`
+    to support it.
+
+    *DHH*
+
+*   Add `action_controller_api` and `action_controller_base` load hooks to be called in `ActiveSupport.on_load`
 
     `ActionController::Base` and `ActionController::API` have differing implementations. This means that
     the one umbrella hook `action_controller` is not able to address certain situations where a method
diff --git a/actionpack/Rakefile b/actionpack/Rakefile
index 31dd1865f9..69408c8aab 100644
--- a/actionpack/Rakefile
+++ b/actionpack/Rakefile
@@ -26,7 +26,7 @@ namespace :test do
 end
 
 task :lines do
-  load File.expand_path("..", File.dirname(__FILE__)) + "/tools/line_statistics"
+  load File.expand_path("..", __dir__) + "/tools/line_statistics"
   files = FileList["lib/**/*.rb"]
   CodeTools::LineStatistics.new(files).print_loc
 end
diff --git a/actionpack/actionpack.gemspec b/actionpack/actionpack.gemspec
index 2c24a54305..31803042dd 100644
--- a/actionpack/actionpack.gemspec
+++ b/actionpack/actionpack.gemspec
@@ -1,4 +1,4 @@
-version = File.read(File.expand_path("../../RAILS_VERSION", __FILE__)).strip
+version = File.read(File.expand_path("../RAILS_VERSION", __dir__)).strip
 
 Gem::Specification.new do |s|
   s.platform    = Gem::Platform::RUBY
diff --git a/actionpack/bin/test b/actionpack/bin/test
index a7beb14b27..470ce93f10 100755
--- a/actionpack/bin/test
+++ b/actionpack/bin/test
@@ -1,4 +1,4 @@
 #!/usr/bin/env ruby
 
 COMPONENT_ROOT = File.expand_path("..", __dir__)
-require File.expand_path("../tools/test", COMPONENT_ROOT)
+require_relative "../../tools/test"
diff --git a/actionpack/lib/abstract_controller/base.rb b/actionpack/lib/abstract_controller/base.rb
index e7cb6347a2..dc79820a82 100644
--- a/actionpack/lib/abstract_controller/base.rb
+++ b/actionpack/lib/abstract_controller/base.rb
@@ -14,8 +14,16 @@ module AbstractController
   # expected to provide their own +render+ method, since rendering means
   # different things depending on the context.
   class Base
+    ##
+    # Returns the body of the HTTP response sent by the controller.
     attr_internal :response_body
+
+    ##
+    # Returns the name of the action this controller is processing.
     attr_internal :action_name
+
+    ##
+    # Returns the formats that can be processed by the controller.
     attr_internal :formats
 
     include ActiveSupport::Configurable
diff --git a/actionpack/lib/abstract_controller/caching.rb b/actionpack/lib/abstract_controller/caching.rb
index 26e3f08bc1..30e3d4426c 100644
--- a/actionpack/lib/abstract_controller/caching.rb
+++ b/actionpack/lib/abstract_controller/caching.rb
@@ -37,8 +37,7 @@ module AbstractController
       config_accessor :enable_fragment_cache_logging
       self.enable_fragment_cache_logging = false
 
-      class_attribute :_view_cache_dependencies
-      self._view_cache_dependencies = []
+      class_attribute :_view_cache_dependencies, default: []
       helper_method :view_cache_dependencies if respond_to?(:helper_method)
     end
 
diff --git a/actionpack/lib/abstract_controller/caching/fragments.rb b/actionpack/lib/abstract_controller/caching/fragments.rb
index c85b4adba1..14e4a82523 100644
--- a/actionpack/lib/abstract_controller/caching/fragments.rb
+++ b/actionpack/lib/abstract_controller/caching/fragments.rb
@@ -25,7 +25,10 @@ module AbstractController
 
         self.fragment_cache_keys = []
 
-        helper_method :fragment_cache_key if respond_to?(:helper_method)
+        if respond_to?(:helper_method)
+          helper_method :fragment_cache_key
+          helper_method :combined_fragment_cache_key
+        end
       end
 
       module ClassMethods
@@ -62,17 +65,36 @@ module AbstractController
       # with the specified +key+ value. The key is expanded using
       # ActiveSupport::Cache.expand_cache_key.
       def fragment_cache_key(key)
+        ActiveSupport::Deprecation.warn(<<-MSG.squish)
+          Calling fragment_cache_key directly is deprecated and will be removed in Rails 6.0.
+          All fragment accessors now use the combined_fragment_cache_key method that retains the key as an array,
+          such that the caching stores can interrogate the parts for cache versions used in
+          recyclable cache keys.
+        MSG
+
         head = self.class.fragment_cache_keys.map { |k| instance_exec(&k) }
         tail = key.is_a?(Hash) ? url_for(key).split("://").last : key
         ActiveSupport::Cache.expand_cache_key([*head, *tail], :views)
       end
 
+      # Given a key (as described in +expire_fragment+), returns
+      # a key array suitable for use in reading, writing, or expiring a
+      # cached fragment. All keys begin with <tt>:views</tt>,
+      # followed by ENV["RAILS_CACHE_ID"] or ENV["RAILS_APP_VERSION"] if set,
+      # followed by any controller-wide key prefix values, ending
+      # with the specified +key+ value.
+      def combined_fragment_cache_key(key)
+        head = self.class.fragment_cache_keys.map { |k| instance_exec(&k) }
+        tail = key.is_a?(Hash) ? url_for(key).split("://").last : key
+        [ :views, (ENV["RAILS_CACHE_ID"] || ENV["RAILS_APP_VERSION"]), *head, *tail ].compact
+      end
+
       # Writes +content+ to the location signified by
       # +key+ (see +expire_fragment+ for acceptable formats).
       def write_fragment(key, content, options = nil)
         return content unless cache_configured?
 
-        key = fragment_cache_key(key)
+        key = combined_fragment_cache_key(key)
         instrument_fragment_cache :write_fragment, key do
           content = content.to_str
           cache_store.write(key, content, options)
@@ -85,7 +107,7 @@ module AbstractController
       def read_fragment(key, options = nil)
         return unless cache_configured?
 
-        key = fragment_cache_key(key)
+        key = combined_fragment_cache_key(key)
         instrument_fragment_cache :read_fragment, key do
           result = cache_store.read(key, options)
           result.respond_to?(:html_safe) ? result.html_safe : result
@@ -96,7 +118,7 @@ module AbstractController
       # +key+ exists (see +expire_fragment+ for acceptable formats).
       def fragment_exist?(key, options = nil)
         return unless cache_configured?
-        key = fragment_cache_key(key)
+        key = combined_fragment_cache_key(key)
 
         instrument_fragment_cache :exist_fragment?, key do
           cache_store.exist?(key, options)
@@ -123,7 +145,7 @@ module AbstractController
       # method (or <tt>delete_matched</tt>, for Regexp keys).
       def expire_fragment(key, options = nil)
         return unless cache_configured?
-        key = fragment_cache_key(key) unless key.is_a?(Regexp)
+        key = combined_fragment_cache_key(key) unless key.is_a?(Regexp)
 
         instrument_fragment_cache :expire_fragment, key do
           if key.is_a?(Regexp)
@@ -135,8 +157,7 @@ module AbstractController
       end
 
       def instrument_fragment_cache(name, key) # :nodoc:
-        payload = instrument_payload(key)
-        ActiveSupport::Notifications.instrument("#{name}.#{instrument_name}", payload) { yield }
+        ActiveSupport::Notifications.instrument("#{name}.#{instrument_name}", instrument_payload(key)) { yield }
       end
     end
   end
diff --git a/actionpack/lib/abstract_controller/callbacks.rb b/actionpack/lib/abstract_controller/callbacks.rb
index ce4ecf17cc..ba7dec6083 100644
--- a/actionpack/lib/abstract_controller/callbacks.rb
+++ b/actionpack/lib/abstract_controller/callbacks.rb
@@ -1,4 +1,24 @@
 module AbstractController
+  # = Abstract Controller Callbacks
+  #
+  # Abstract Controller provides hooks during the life cycle of a controller action.
+  # Callbacks allow you to trigger logic during this cycle. Available callbacks are:
+  #
+  # * <tt>after_action</tt>
+  # * <tt>append_after_action</tt>
+  # * <tt>append_around_action</tt>
+  # * <tt>append_before_action</tt>
+  # * <tt>around_action</tt>
+  # * <tt>before_action</tt>
+  # * <tt>prepend_after_action</tt>
+  # * <tt>prepend_around_action</tt>
+  # * <tt>prepend_before_action</tt>
+  # * <tt>skip_after_action</tt>
+  # * <tt>skip_around_action</tt>
+  # * <tt>skip_before_action</tt>
+  #
+  # NOTE: Calling the same callback multiple times will overwrite previous callback definitions.
+  #
   module Callbacks
     extend ActiveSupport::Concern
 
diff --git a/actionpack/lib/abstract_controller/helpers.rb b/actionpack/lib/abstract_controller/helpers.rb
index ef3be7af83..2e50637c39 100644
--- a/actionpack/lib/abstract_controller/helpers.rb
+++ b/actionpack/lib/abstract_controller/helpers.rb
@@ -5,11 +5,8 @@ module AbstractController
     extend ActiveSupport::Concern
 
     included do
-      class_attribute :_helpers
-      self._helpers = Module.new
-
-      class_attribute :_helper_methods
-      self._helper_methods = Array.new
+      class_attribute :_helpers, default: Module.new
+      class_attribute :_helper_methods, default: Array.new
     end
 
     class MissingHelperError < LoadError
diff --git a/actionpack/lib/abstract_controller/translation.rb b/actionpack/lib/abstract_controller/translation.rb
index 9e3858802a..e4ac95df50 100644
--- a/actionpack/lib/abstract_controller/translation.rb
+++ b/actionpack/lib/abstract_controller/translation.rb
@@ -13,7 +13,7 @@ module AbstractController
         path = controller_path.tr("/", ".")
         defaults = [:"#{path}#{key}"]
         defaults << options[:default] if options[:default]
-        options[:default] = defaults
+        options[:default] = defaults.flatten
         key = "#{path}.#{action_name}#{key}"
       end
       I18n.translate(key, options)
diff --git a/actionpack/lib/action_controller/log_subscriber.rb b/actionpack/lib/action_controller/log_subscriber.rb
index d29a5fe68f..d00fcbcd13 100644
--- a/actionpack/lib/action_controller/log_subscriber.rb
+++ b/actionpack/lib/action_controller/log_subscriber.rb
@@ -60,9 +60,9 @@ module ActionController
       class_eval <<-METHOD, __FILE__, __LINE__ + 1
         def #{method}(event)
           return unless logger.info? && ActionController::Base.enable_fragment_cache_logging
-          key_or_path = event.payload[:key] || event.payload[:path]
+          key         = ActiveSupport::Cache.expand_cache_key(event.payload[:key] || event.payload[:path])
           human_name  = #{method.to_s.humanize.inspect}
-          info("\#{human_name} \#{key_or_path} (\#{event.duration.round(1)}ms)")
+          info("\#{human_name} \#{key} (\#{event.duration.round(1)}ms)")
         end
       METHOD
     end
diff --git a/actionpack/lib/action_controller/metal.rb b/actionpack/lib/action_controller/metal.rb
index 246644dcbd..96c708f45a 100644
--- a/actionpack/lib/action_controller/metal.rb
+++ b/actionpack/lib/action_controller/metal.rb
@@ -208,8 +208,7 @@ module ActionController
       @_request.reset_session
     end
 
-    class_attribute :middleware_stack
-    self.middleware_stack = ActionController::MiddlewareStack.new
+    class_attribute :middleware_stack, default: ActionController::MiddlewareStack.new
 
     def self.inherited(base) # :nodoc:
       base.middleware_stack = middleware_stack.dup
diff --git a/actionpack/lib/action_controller/metal/conditional_get.rb b/actionpack/lib/action_controller/metal/conditional_get.rb
index eb636fa3f6..0525252c7c 100644
--- a/actionpack/lib/action_controller/metal/conditional_get.rb
+++ b/actionpack/lib/action_controller/metal/conditional_get.rb
@@ -7,8 +7,7 @@ module ActionController
     include Head
 
     included do
-      class_attribute :etaggers
-      self.etaggers = []
+      class_attribute :etaggers, default: []
     end
 
     module ClassMethods
diff --git a/actionpack/lib/action_controller/metal/etag_with_template_digest.rb b/actionpack/lib/action_controller/metal/etag_with_template_digest.rb
index 798564db96..69c3979a0e 100644
--- a/actionpack/lib/action_controller/metal/etag_with_template_digest.rb
+++ b/actionpack/lib/action_controller/metal/etag_with_template_digest.rb
@@ -22,8 +22,7 @@ module ActionController
     include ActionController::ConditionalGet
 
     included do
-      class_attribute :etag_with_template_digest
-      self.etag_with_template_digest = true
+      class_attribute :etag_with_template_digest, default: true
 
       ActiveSupport.on_load :action_view, yield: true do
         etag do |options|
diff --git a/actionpack/lib/action_controller/metal/flash.rb b/actionpack/lib/action_controller/metal/flash.rb
index 347fbf0e74..24d1097ebe 100644
--- a/actionpack/lib/action_controller/metal/flash.rb
+++ b/actionpack/lib/action_controller/metal/flash.rb
@@ -3,8 +3,7 @@ module ActionController #:nodoc:
     extend ActiveSupport::Concern
 
     included do
-      class_attribute :_flash_types, instance_accessor: false
-      self._flash_types = []
+      class_attribute :_flash_types, instance_accessor: false, default: []
 
       delegate :flash, to: :request
       add_flash_types(:alert, :notice)
diff --git a/actionpack/lib/action_controller/metal/helpers.rb b/actionpack/lib/action_controller/metal/helpers.rb
index 476d081239..913a4b9a04 100644
--- a/actionpack/lib/action_controller/metal/helpers.rb
+++ b/actionpack/lib/action_controller/metal/helpers.rb
@@ -53,9 +53,8 @@ module ActionController
     include AbstractController::Helpers
 
     included do
-      class_attribute :helpers_path, :include_all_helpers
-      self.helpers_path ||= []
-      self.include_all_helpers = true
+      class_attribute :helpers_path, default: []
+      class_attribute :include_all_helpers, default: true
     end
 
     module ClassMethods
diff --git a/actionpack/lib/action_controller/metal/params_wrapper.rb b/actionpack/lib/action_controller/metal/params_wrapper.rb
index a89fc1678b..68881b8402 100644
--- a/actionpack/lib/action_controller/metal/params_wrapper.rb
+++ b/actionpack/lib/action_controller/metal/params_wrapper.rb
@@ -159,8 +159,7 @@ module ActionController
     end
 
     included do
-      class_attribute :_wrapper_options
-      self._wrapper_options = Options.from_hash(format: [])
+      class_attribute :_wrapper_options, default: Options.from_hash(format: [])
     end
 
     module ClassMethods
diff --git a/actionpack/lib/action_controller/metal/renderers.rb b/actionpack/lib/action_controller/metal/renderers.rb
index 733aca195d..23c21b0501 100644
--- a/actionpack/lib/action_controller/metal/renderers.rb
+++ b/actionpack/lib/action_controller/metal/renderers.rb
@@ -26,8 +26,7 @@ module ActionController
     RENDERERS = Set.new
 
     included do
-      class_attribute :_renderers
-      self._renderers = Set.new.freeze
+      class_attribute :_renderers, default: Set.new.freeze
     end
 
     # Used in <tt>ActionController::Base</tt>
diff --git a/actionpack/lib/action_controller/metal/strong_parameters.rb b/actionpack/lib/action_controller/metal/strong_parameters.rb
index 20330b5091..cd99e3125f 100644
--- a/actionpack/lib/action_controller/metal/strong_parameters.rb
+++ b/actionpack/lib/action_controller/metal/strong_parameters.rb
@@ -119,8 +119,7 @@ module ActionController
   #   params[:key]  # => "value"
   #   params["key"] # => "value"
   class Parameters
-    cattr_accessor :permit_all_parameters, instance_accessor: false
-    self.permit_all_parameters = false
+    cattr_accessor :permit_all_parameters, instance_accessor: false, default: false
 
     cattr_accessor :action_on_unpermitted_parameters, instance_accessor: false
 
@@ -205,8 +204,7 @@ module ActionController
     # config. For instance:
     #
     #    config.always_permitted_parameters = %w( controller action format )
-    cattr_accessor :always_permitted_parameters
-    self.always_permitted_parameters = %w( controller action )
+    cattr_accessor :always_permitted_parameters, default: %w( controller action )
 
     # Returns a new instance of <tt>ActionController::Parameters</tt>.
     # Also, sets the +permitted+ attribute to the default value of
diff --git a/actionpack/lib/action_dispatch/http/mime_negotiation.rb b/actionpack/lib/action_dispatch/http/mime_negotiation.rb
index 19f89edbc1..5994a01c78 100644
--- a/actionpack/lib/action_dispatch/http/mime_negotiation.rb
+++ b/actionpack/lib/action_dispatch/http/mime_negotiation.rb
@@ -6,8 +6,7 @@ module ActionDispatch
       extend ActiveSupport::Concern
 
       included do
-        mattr_accessor :ignore_accept_header
-        self.ignore_accept_header = false
+        mattr_accessor :ignore_accept_header, default: false
       end
 
       # The MIME type of the HTTP request, such as Mime[:xml].
diff --git a/actionpack/lib/action_dispatch/http/response.rb b/actionpack/lib/action_dispatch/http/response.rb
index 2ee52eeb48..3c91677d55 100644
--- a/actionpack/lib/action_dispatch/http/response.rb
+++ b/actionpack/lib/action_dispatch/http/response.rb
@@ -81,8 +81,8 @@ module ActionDispatch # :nodoc:
     LOCATION     = "Location".freeze
     NO_CONTENT_CODES = [100, 101, 102, 204, 205, 304]
 
-    cattr_accessor(:default_charset) { "utf-8" }
-    cattr_accessor(:default_headers)
+    cattr_accessor :default_charset, default: "utf-8"
+    cattr_accessor :default_headers
 
     include Rack::Response::Helpers
     # Aliasing these off because AD::Http::Cache::Response defines them.
diff --git a/actionpack/lib/action_dispatch/http/url.rb b/actionpack/lib/action_dispatch/http/url.rb
index b6be48a48b..f902fe36e0 100644
--- a/actionpack/lib/action_dispatch/http/url.rb
+++ b/actionpack/lib/action_dispatch/http/url.rb
@@ -7,8 +7,7 @@ module ActionDispatch
       HOST_REGEXP     = /(^[^:]+:\/\/)?(\[[^\]]+\]|[^:]+)(?::(\d+$))?/
       PROTOCOL_REGEXP = /^([^:]+)(:)?(\/\/)?$/
 
-      mattr_accessor :tld_length
-      self.tld_length = 1
+      mattr_accessor :tld_length, default: 1
 
       class << self
         # Returns the domain part of a host given the domain level.
diff --git a/actionpack/lib/action_dispatch/journey/gtg/simulator.rb b/actionpack/lib/action_dispatch/journey/gtg/simulator.rb
index d692f6415c..62f052ced6 100644
--- a/actionpack/lib/action_dispatch/journey/gtg/simulator.rb
+++ b/actionpack/lib/action_dispatch/journey/gtg/simulator.rb
@@ -18,14 +18,6 @@ module ActionDispatch
           @tt = transition_table
         end
 
-        def simulate(string)
-          ms = memos(string) { return }
-          MatchData.new(ms)
-        end
-
-        alias :=~    :simulate
-        alias :match :simulate
-
         def memos(string)
           input = StringScanner.new(string)
           state = [0]
diff --git a/actionpack/lib/action_dispatch/journey/gtg/transition_table.rb b/actionpack/lib/action_dispatch/journey/gtg/transition_table.rb
index e1ac2c873e..45aff287b1 100644
--- a/actionpack/lib/action_dispatch/journey/gtg/transition_table.rb
+++ b/actionpack/lib/action_dispatch/journey/gtg/transition_table.rb
@@ -82,7 +82,7 @@ module ActionDispatch
         end
 
         def visualizer(paths, title = "FSM")
-          viz_dir   = File.join File.dirname(__FILE__), "..", "visualizer"
+          viz_dir   = File.join __dir__, "..", "visualizer"
           fsm_js    = File.read File.join(viz_dir, "fsm.js")
           fsm_css   = File.read File.join(viz_dir, "fsm.css")
           erb       = File.read File.join(viz_dir, "index.html.erb")
diff --git a/actionpack/lib/action_dispatch/journey/route.rb b/actionpack/lib/action_dispatch/journey/route.rb
index 7bc15aa6b3..0acbac1d9d 100644
--- a/actionpack/lib/action_dispatch/journey/route.rb
+++ b/actionpack/lib/action_dispatch/journey/route.rb
@@ -10,11 +10,11 @@ module ActionDispatch
       module VerbMatchers
         VERBS = %w{ DELETE GET HEAD OPTIONS LINK PATCH POST PUT TRACE UNLINK }
         VERBS.each do |v|
-          class_eval <<-eoc
-          class #{v}
-            def self.verb; name.split("::").last; end
-            def self.call(req); req.#{v.downcase}?; end
-          end
+          class_eval <<-eoc, __FILE__, __LINE__ + 1
+            class #{v}
+              def self.verb; name.split("::").last; end
+              def self.call(req); req.#{v.downcase}?; end
+            end
           eoc
         end
 
diff --git a/actionpack/lib/action_dispatch/middleware/cookies.rb b/actionpack/lib/action_dispatch/middleware/cookies.rb
index e565c03a8a..533925ebe1 100644
--- a/actionpack/lib/action_dispatch/middleware/cookies.rb
+++ b/actionpack/lib/action_dispatch/middleware/cookies.rb
@@ -43,6 +43,10 @@ module ActionDispatch
       get_header Cookies::ENCRYPTED_SIGNED_COOKIE_SALT
     end
 
+    def authenticated_encrypted_cookie_salt
+      get_header Cookies::AUTHENTICATED_ENCRYPTED_COOKIE_SALT
+    end
+
     def secret_token
       get_header Cookies::SECRET_TOKEN
     end
@@ -149,6 +153,7 @@ module ActionDispatch
     SIGNED_COOKIE_SALT = "action_dispatch.signed_cookie_salt".freeze
     ENCRYPTED_COOKIE_SALT = "action_dispatch.encrypted_cookie_salt".freeze
     ENCRYPTED_SIGNED_COOKIE_SALT = "action_dispatch.encrypted_signed_cookie_salt".freeze
+    AUTHENTICATED_ENCRYPTED_COOKIE_SALT = "action_dispatch.authenticated_encrypted_cookie_salt".freeze
     SECRET_TOKEN = "action_dispatch.secret_token".freeze
     SECRET_KEY_BASE = "action_dispatch.secret_key_base".freeze
     COOKIES_SERIALIZER = "action_dispatch.cookies_serializer".freeze
@@ -207,6 +212,9 @@ module ActionDispatch
       # If +secrets.secret_key_base+ and +secrets.secret_token+ (deprecated) are both set,
       # legacy cookies signed with the old key generator will be transparently upgraded.
       #
+      # If +config.action_dispatch.encrypted_cookie_salt+ and +config.action_dispatch.encrypted_signed_cookie_salt+
+      # are both set, legacy cookies encrypted with HMAC AES-256-CBC will be transparently upgraded.
+      #
       # This jar requires that you set a suitable secret for the verification on your app's +secrets.secret_key_base+.
       #
       # Example:
@@ -219,6 +227,8 @@ module ActionDispatch
         @encrypted ||=
           if upgrade_legacy_signed_cookies?
             UpgradeLegacyEncryptedCookieJar.new(self)
+          elsif upgrade_legacy_hmac_aes_cbc_cookies?
+            UpgradeLegacyHmacAesCbcCookieJar.new(self)
           else
             EncryptedCookieJar.new(self)
           end
@@ -240,6 +250,13 @@ module ActionDispatch
         def upgrade_legacy_signed_cookies?
           request.secret_token.present? && request.secret_key_base.present?
         end
+
+        def upgrade_legacy_hmac_aes_cbc_cookies?
+          request.secret_key_base.present?                       &&
+            request.authenticated_encrypted_cookie_salt.present? &&
+            request.encrypted_signed_cookie_salt.present?        &&
+            request.encrypted_cookie_salt.present?
+        end
     end
 
     # Passing the ActiveSupport::MessageEncryptor::NullSerializer downstream
@@ -415,8 +432,7 @@ module ActionDispatch
         end
       end
 
-      mattr_accessor :always_write_cookie
-      self.always_write_cookie = false
+      mattr_accessor :always_write_cookie, default: false
 
       private
 
@@ -576,9 +592,11 @@ module ActionDispatch
             "Read the upgrade documentation to learn more about this new config option."
         end
 
-        secret = key_generator.generate_key(request.encrypted_cookie_salt || "")[0, ActiveSupport::MessageEncryptor.key_len]
-        sign_secret = key_generator.generate_key(request.encrypted_signed_cookie_salt || "")
-        @encryptor = ActiveSupport::MessageEncryptor.new(secret, sign_secret, digest: digest, serializer: ActiveSupport::MessageEncryptor::NullSerializer)
+        cipher = "aes-256-gcm"
+        key_len = ActiveSupport::MessageEncryptor.key_len(cipher)
+        secret = key_generator.generate_key(request.authenticated_encrypted_cookie_salt || "")[0, key_len]
+
+        @encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: ActiveSupport::MessageEncryptor::NullSerializer)
       end
 
       private
@@ -603,6 +621,32 @@ module ActionDispatch
       include VerifyAndUpgradeLegacySignedMessage
     end
 
+    # UpgradeLegacyHmacAesCbcCookieJar is used by ActionDispatch::Session::CookieStore
+    # to upgrade cookies encrypted with AES-256-CBC with HMAC to AES-256-GCM
+    class UpgradeLegacyHmacAesCbcCookieJar < EncryptedCookieJar
+      def initialize(parent_jar)
+        super
+
+        secret = key_generator.generate_key(request.encrypted_cookie_salt || "")[0, ActiveSupport::MessageEncryptor.key_len]
+        sign_secret = key_generator.generate_key(request.encrypted_signed_cookie_salt || "")
+
+        @legacy_encryptor = ActiveSupport::MessageEncryptor.new(secret, sign_secret, cipher: "aes-256-cbc", digest: digest, serializer: ActiveSupport::MessageEncryptor::NullSerializer)
+      end
+
+      def decrypt_and_verify_legacy_encrypted_message(name, signed_message)
+        deserialize(name, @legacy_encryptor.decrypt_and_verify(signed_message)).tap do |value|
+          self[name] = { value: value }
+        end
+      rescue ActiveSupport::MessageVerifier::InvalidSignature, ActiveSupport::MessageEncryptor::InvalidMessage
+        nil
+      end
+
+      private
+        def parse(name, signed_message)
+          super || decrypt_and_verify_legacy_encrypted_message(name, signed_message)
+        end
+    end
+
     def initialize(app)
       @app = app
     end
diff --git a/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb b/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
index 1c720c5a8e..336a775880 100644
--- a/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
+++ b/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
@@ -10,7 +10,7 @@ module ActionDispatch
   # This middleware is responsible for logging exceptions and
   # showing a debugging page in case the request is local.
   class DebugExceptions
-    RESCUES_TEMPLATE_PATH = File.expand_path("../templates", __FILE__)
+    RESCUES_TEMPLATE_PATH = File.expand_path("templates", __dir__)
 
     class DebugView < ActionView::Base
       def debug_params(params)
diff --git a/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
index 397f0a8b92..08b4541d24 100644
--- a/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
+++ b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
@@ -3,9 +3,7 @@ require "rack/utils"
 
 module ActionDispatch
   class ExceptionWrapper
-    cattr_accessor :rescue_responses
-    @@rescue_responses = Hash.new(:internal_server_error)
-    @@rescue_responses.merge!(
+    cattr_accessor :rescue_responses, default: Hash.new(:internal_server_error).merge!(
       "ActionController::RoutingError"               => :not_found,
       "AbstractController::ActionNotFound"           => :not_found,
       "ActionController::MethodNotAllowed"           => :method_not_allowed,
@@ -21,9 +19,7 @@ module ActionDispatch
       "Rack::QueryParser::InvalidParameterError"     => :bad_request
     )
 
-    cattr_accessor :rescue_templates
-    @@rescue_templates = Hash.new("diagnostics")
-    @@rescue_templates.merge!(
+    cattr_accessor :rescue_templates, default: Hash.new("diagnostics").merge!(
       "ActionView::MissingTemplate"         => "missing_template",
       "ActionController::RoutingError"      => "routing_error",
       "AbstractController::ActionNotFound"  => "unknown_action",
diff --git a/actionpack/lib/action_dispatch/middleware/static.rb b/actionpack/lib/action_dispatch/middleware/static.rb
index 5d10129d21..fb99f13a1c 100644
--- a/actionpack/lib/action_dispatch/middleware/static.rb
+++ b/actionpack/lib/action_dispatch/middleware/static.rb
@@ -6,11 +6,11 @@ module ActionDispatch
   # When initialized, it can accept optional HTTP headers, which will be set
   # when a response containing a file's contents is delivered.
   #
-  # This middleware will render the file specified in `env["PATH_INFO"]`
+  # This middleware will render the file specified in <tt>env["PATH_INFO"]</tt>
   # where the base path is in the +root+ directory. For example, if the +root+
-  # is set to `public/`, then a request with `env["PATH_INFO"]` of
-  # `assets/application.js` will return a response with the contents of a file
-  # located at `public/assets/application.js` if the file exists. If the file
+  # is set to +public/+, then a request with <tt>env["PATH_INFO"]</tt> of
+  # +assets/application.js+ will return a response with the contents of a file
+  # located at +public/assets/application.js+ if the file exists. If the file
   # does not exist, a 404 "File not Found" response will be returned.
   class FileHandler
     def initialize(root, index: "index", headers: {})
@@ -23,8 +23,8 @@ module ActionDispatch
     # correct read permissions, the return value is a URI-escaped string
     # representing the filename. Otherwise, false is returned.
     #
-    # Used by the `Static` class to check the existence of a valid file
-    # in the server's `public/` directory (see Static#call).
+    # Used by the +Static+ class to check the existence of a valid file
+    # in the server's +public/+ directory (see Static#call).
     def match?(path)
       path = ::Rack::Utils.unescape_path path
       return false unless ::Rack::Utils.valid_path? path
@@ -99,7 +99,7 @@ module ActionDispatch
   # This middleware will attempt to return the contents of a file's body from
   # disk in the response. If a file is not found on disk, the request will be
   # delegated to the application stack. This middleware is commonly initialized
-  # to serve assets from a server's `public/` directory.
+  # to serve assets from a server's +public/+ directory.
   #
   # This middleware verifies the path to ensure that only files
   # living in the root directory can be rendered. A request cannot
diff --git a/actionpack/lib/action_dispatch/railtie.rb b/actionpack/lib/action_dispatch/railtie.rb
index 16a18a7f25..7662e164b8 100644
--- a/actionpack/lib/action_dispatch/railtie.rb
+++ b/actionpack/lib/action_dispatch/railtie.rb
@@ -16,6 +16,7 @@ module ActionDispatch
     config.action_dispatch.signed_cookie_salt = "signed cookie"
     config.action_dispatch.encrypted_cookie_salt = "encrypted cookie"
     config.action_dispatch.encrypted_signed_cookie_salt = "signed encrypted cookie"
+    config.action_dispatch.use_authenticated_cookie_encryption = false
     config.action_dispatch.perform_deep_munge = true
 
     config.action_dispatch.default_headers = {
@@ -36,6 +37,8 @@ module ActionDispatch
       ActionDispatch::ExceptionWrapper.rescue_responses.merge!(config.action_dispatch.rescue_responses)
       ActionDispatch::ExceptionWrapper.rescue_templates.merge!(config.action_dispatch.rescue_templates)
 
+      config.action_dispatch.authenticated_encrypted_cookie_salt = "authenticated encrypted cookie" if config.action_dispatch.use_authenticated_cookie_encryption
+
       config.action_dispatch.always_write_cookie = Rails.env.development? if config.action_dispatch.always_write_cookie.nil?
       ActionDispatch::Cookies::CookieJar.always_write_cookie = config.action_dispatch.always_write_cookie
 
diff --git a/actionpack/lib/action_dispatch/request/session.rb b/actionpack/lib/action_dispatch/request/session.rb
index 74ba6466cf..3547a8604f 100644
--- a/actionpack/lib/action_dispatch/request/session.rb
+++ b/actionpack/lib/action_dispatch/request/session.rb
@@ -101,11 +101,13 @@ module ActionDispatch
 
       # Returns keys of the session as Array.
       def keys
+        load_for_read!
         @delegate.keys
       end
 
       # Returns values of the session as Array.
       def values
+        load_for_read!
         @delegate.values
       end
 
diff --git a/actionpack/lib/action_dispatch/request/utils.rb b/actionpack/lib/action_dispatch/request/utils.rb
index 3615e4b1d8..4f79c4c21e 100644
--- a/actionpack/lib/action_dispatch/request/utils.rb
+++ b/actionpack/lib/action_dispatch/request/utils.rb
@@ -1,8 +1,7 @@
 module ActionDispatch
   class Request
     class Utils # :nodoc:
-      mattr_accessor :perform_deep_munge
-      self.perform_deep_munge = true
+      mattr_accessor :perform_deep_munge, default: true
 
       def self.each_param_value(params, &block)
         case params
diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 74904e3d45..88deee5f5e 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -1837,7 +1837,7 @@ module ActionDispatch
             path_types.fetch(String, []).each do |_path|
               route_options = options.dup
               if _path && option_path
-                raise ArgumentError, "Ambigous route definition. Both :path and the route path where specified as strings."
+                raise ArgumentError, "Ambiguous route definition. Both :path and the route path where specified as strings."
               end
               to = get_to_from_path(_path, to, route_options[:action])
               decomposed_match(_path, controller, route_options, _path, to, via, formatted, anchor, options_constraints)
@@ -2038,8 +2038,8 @@ module ActionDispatch
         #     { controller: "pages", action: "index", subdomain: "www" }
         #   end
         #
-        # The return value from the block passed to `direct` must be a valid set of
-        # arguments for `url_for` which will actually build the URL string. This can
+        # The return value from the block passed to +direct+ must be a valid set of
+        # arguments for +url_for+ which will actually build the URL string. This can
         # be one of the following:
         #
         #   * A string, which is treated as a generated URL
@@ -2058,17 +2058,17 @@ module ActionDispatch
         #     [ :products, options.merge(params.permit(:page, :size).to_h.symbolize_keys) ]
         #   end
         #
-        # In this instance the `params` object comes from the context in which the the
+        # In this instance the +params+ object comes from the context in which the the
         # block is executed, e.g. generating a URL inside a controller action or a view.
         # If the block is executed where there isn't a params object such as this:
         #
         #   Rails.application.routes.url_helpers.browse_path
         #
-        # then it will raise a `NameError`. Because of this you need to be aware of the
+        # then it will raise a +NameError+. Because of this you need to be aware of the
         # context in which you will use your custom URL helper when defining it.
         #
-        # NOTE: The `direct` method can't be used inside of a scope block such as
-        # `namespace` or `scope` and will raise an error if it detects that it is.
+        # NOTE: The +direct+ method can't be used inside of a scope block such as
+        # +namespace+ or +scope+ and will raise an error if it detects that it is.
         def direct(name, options = {}, &block)
           unless @scope.root?
             raise RuntimeError, "The direct method can't be used inside a routes scope block"
@@ -2078,8 +2078,8 @@ module ActionDispatch
         end
 
         # Define custom polymorphic mappings of models to URLs. This alters the
-        # behavior of `polymorphic_url` and consequently the behavior of
-        # `link_to` and `form_for` when passed a model instance, e.g:
+        # behavior of +polymorphic_url+ and consequently the behavior of
+        # +link_to+ and +form_for+ when passed a model instance, e.g:
         #
         #   resource :basket
         #
@@ -2087,8 +2087,8 @@ module ActionDispatch
         #     [:basket]
         #   end
         #
-        # This will now generate "/basket" when a `Basket` instance is passed to
-        # `link_to` or `form_for` instead of the standard "/baskets/:id".
+        # This will now generate "/basket" when a +Basket+ instance is passed to
+        # +link_to+ or +form_for+ instead of the standard "/baskets/:id".
         #
         # NOTE: This custom behavior only applies to simple polymorphic URLs where
         # a single model instance is passed and not more complicated forms, e.g:
@@ -2105,7 +2105,7 @@ module ActionDispatch
         #   link_to "Profile", @current_user
         #   link_to "Profile", [:admin, @current_user]
         #
-        # The first `link_to` will generate "/profile" but the second will generate
+        # The first +link_to+ will generate "/profile" but the second will generate
         # the standard polymorphic URL of "/admin/users/1".
         #
         # You can pass options to a polymorphic mapping - the arity for the block
@@ -2116,11 +2116,11 @@ module ActionDispatch
         #   end
         #
         # This generates the URL "/basket#items" because when the last item in an
-        # array passed to `polymorphic_url` is a hash then it's treated as options
+        # array passed to +polymorphic_url+ is a hash then it's treated as options
         # to the URL helper that gets called.
         #
-        # NOTE: The `resolve` method can't be used inside of a scope block such as
-        # `namespace` or `scope` and will raise an error if it detects that it is.
+        # NOTE: The +resolve+ method can't be used inside of a scope block such as
+        # +namespace+ or +scope+ and will raise an error if it detects that it is.
         def resolve(*args, &block)
           unless @scope.root?
             raise RuntimeError, "The resolve method can't be used inside a routes scope block"
diff --git a/actionpack/lib/action_dispatch/system_test_case.rb b/actionpack/lib/action_dispatch/system_test_case.rb
index 98fdb36c91..c39a135ce0 100644
--- a/actionpack/lib/action_dispatch/system_test_case.rb
+++ b/actionpack/lib/action_dispatch/system_test_case.rb
@@ -66,14 +66,18 @@ module ActionDispatch
   #
   # To use a headless driver, like Poltergeist, update your Gemfile to use
   # Poltergeist instead of Selenium and then declare the driver name in the
-  # +application_system_test_case.rb+ file. In this case you would leave out the +:using+
-  # option because the driver is headless.
+  # +application_system_test_case.rb+ file. In this case, you would leave out
+  # the +:using+ option because the driver is headless, but you can still use
+  # +:screen_size+ to change the size of the browser screen, also you can use
+  # +:options+ to pass options supported by the driver. Please refer to your
+  # driver documentation to learn about supported options.
   #
   #   require "test_helper"
   #   require "capybara/poltergeist"
   #
   #   class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
-  #     driven_by :poltergeist
+  #     driven_by :poltergeist, screen_size: [1400, 1400], options:
+  #       { js_errors: true }
   #   end
   #
   # Because <tt>ActionDispatch::SystemTestCase</tt> is a shim between Capybara
diff --git a/actionpack/lib/action_dispatch/system_testing/driver.rb b/actionpack/lib/action_dispatch/system_testing/driver.rb
index 5cf17883f7..1a027f2e23 100644
--- a/actionpack/lib/action_dispatch/system_testing/driver.rb
+++ b/actionpack/lib/action_dispatch/system_testing/driver.rb
@@ -9,23 +9,42 @@ module ActionDispatch
       end
 
       def use
-        register if selenium?
+        register unless rack_test?
+
         setup
       end
 
       private
-        def selenium?
-          @name == :selenium
+        def rack_test?
+          @name == :rack_test
         end
 
         def register
           Capybara.register_driver @name do |app|
-            Capybara::Selenium::Driver.new(app, { browser: @browser }.merge(@options)).tap do |driver|
-              driver.browser.manage.window.size = Selenium::WebDriver::Dimension.new(*@screen_size)
+            case @name
+            when :selenium then register_selenium(app)
+            when :poltergeist then register_poltergeist(app)
+            when :webkit then register_webkit(app)
             end
           end
         end
 
+        def register_selenium(app)
+          Capybara::Selenium::Driver.new(app, { browser: @browser }.merge(@options)).tap do |driver|
+            driver.browser.manage.window.size = Selenium::WebDriver::Dimension.new(*@screen_size)
+          end
+        end
+
+        def register_poltergeist(app)
+          Capybara::Poltergeist::Driver.new(app, @options.merge(window_size: @screen_size))
+        end
+
+        def register_webkit(app)
+          Capybara::Webkit::Driver.new(app, Capybara::Webkit::Configuration.to_hash.merge(@options)).tap do |driver|
+            driver.resize_window(*@screen_size)
+          end
+        end
+
         def setup
           Capybara.current_driver = @name
         end
diff --git a/actionpack/lib/action_dispatch/system_testing/test_helpers/setup_and_teardown.rb b/actionpack/lib/action_dispatch/system_testing/test_helpers/setup_and_teardown.rb
index 187ba2cc5f..f03f0d4299 100644
--- a/actionpack/lib/action_dispatch/system_testing/test_helpers/setup_and_teardown.rb
+++ b/actionpack/lib/action_dispatch/system_testing/test_helpers/setup_and_teardown.rb
@@ -2,7 +2,12 @@ module ActionDispatch
   module SystemTesting
     module TestHelpers
       module SetupAndTeardown # :nodoc:
-        DEFAULT_HOST = "127.0.0.1"
+        DEFAULT_HOST = "http://127.0.0.1"
+
+        def host!(host)
+          super
+          Capybara.app_host = host
+        end
 
         def before_setup
           host! DEFAULT_HOST
diff --git a/actionpack/test/abstract/translation_test.rb b/actionpack/test/abstract/translation_test.rb
index 0c4071df8d..4893144905 100644
--- a/actionpack/test/abstract/translation_test.rb
+++ b/actionpack/test/abstract/translation_test.rb
@@ -62,6 +62,7 @@ module AbstractController
       def test_default_translation
         @controller.stub :action_name, :index do
           assert_equal "bar", @controller.t("one.two")
+          assert_equal "baz", @controller.t(".twoz", default: ["baz", :twoz])
         end
       end
 
diff --git a/actionpack/test/abstract_unit.rb b/actionpack/test/abstract_unit.rb
index 4185ce1a1f..bd118b46be 100644
--- a/actionpack/test/abstract_unit.rb
+++ b/actionpack/test/abstract_unit.rb
@@ -1,6 +1,6 @@
-$:.unshift(File.dirname(__FILE__) + "/lib")
-$:.unshift(File.dirname(__FILE__) + "/fixtures/helpers")
-$:.unshift(File.dirname(__FILE__) + "/fixtures/alternate_helpers")
+$:.unshift File.expand_path("lib", __dir__)
+$:.unshift File.expand_path("fixtures/helpers", __dir__)
+$:.unshift File.expand_path("fixtures/alternate_helpers", __dir__)
 
 require "active_support/core_ext/kernel/reporting"
 
@@ -56,7 +56,7 @@ ActiveSupport::Deprecation.debug = true
 # Disable available locale checks to avoid warnings running the test suite.
 I18n.enforce_available_locales = false
 
-FIXTURE_LOAD_PATH = File.join(File.dirname(__FILE__), "fixtures")
+FIXTURE_LOAD_PATH = File.join(__dir__, "fixtures")
 
 SharedTestRoutes = ActionDispatch::Routing::RouteSet.new
 
@@ -156,7 +156,7 @@ class ActionDispatch::IntegrationTest < ActiveSupport::TestCase
   end
 
   def with_autoload_path(path)
-    path = File.join(File.dirname(__FILE__), "fixtures", path)
+    path = File.join(__dir__, "fixtures", path)
     if ActiveSupport::Dependencies.autoload_paths.include?(path)
       yield
     else
diff --git a/actionpack/test/controller/action_pack_assertions_test.rb b/actionpack/test/controller/action_pack_assertions_test.rb
index 9ab152fc5c..73aab5848b 100644
--- a/actionpack/test/controller/action_pack_assertions_test.rb
+++ b/actionpack/test/controller/action_pack_assertions_test.rb
@@ -83,7 +83,7 @@ class ActionPackAssertionsController < ActionController::Base
   end
 
   def render_file_absolute_path
-    render file: File.expand_path("../../../README.rdoc", __FILE__)
+    render file: File.expand_path("../../README.rdoc", __dir__)
   end
 
   def render_file_relative_path
diff --git a/actionpack/test/controller/api/data_streaming_test.rb b/actionpack/test/controller/api/data_streaming_test.rb
index f15b78d102..e6419b9adf 100644
--- a/actionpack/test/controller/api/data_streaming_test.rb
+++ b/actionpack/test/controller/api/data_streaming_test.rb
@@ -1,7 +1,7 @@
 require "abstract_unit"
 
 module TestApiFileUtils
-  def file_path() File.expand_path(__FILE__) end
+  def file_path() __FILE__ end
   def file_data() @data ||= File.open(file_path, "rb") { |f| f.read } end
 end
 
diff --git a/actionpack/test/controller/caching_test.rb b/actionpack/test/controller/caching_test.rb
index fa8d9dc09a..c86dcafee5 100644
--- a/actionpack/test/controller/caching_test.rb
+++ b/actionpack/test/controller/caching_test.rb
@@ -4,7 +4,7 @@ require "lib/controller/fake_models"
 
 CACHE_DIR = "test_cache"
 # Don't change '/../temp/' cavalierly or you might hose something you don't want hosed
-FILE_STORE_PATH = File.join(File.dirname(__FILE__), "/../temp/", CACHE_DIR)
+FILE_STORE_PATH = File.join(__dir__, "../temp/", CACHE_DIR)
 
 class FragmentCachingMetalTestController < ActionController::Metal
   abstract!
@@ -26,10 +26,6 @@ class FragmentCachingMetalTest < ActionController::TestCase
     @controller.request = @request
     @controller.response = @response
   end
-
-  def test_fragment_cache_key
-    assert_equal "views/what a key", @controller.fragment_cache_key("what a key")
-  end
 end
 
 class CachingController < ActionController::Base
@@ -43,6 +39,8 @@ class FragmentCachingTestController < CachingController
 end
 
 class FragmentCachingTest < ActionController::TestCase
+  ModelWithKeyAndVersion = Struct.new(:cache_key, :cache_version)
+
   def setup
     super
     @store = ActiveSupport::Cache::MemoryStore.new
@@ -53,12 +51,25 @@ class FragmentCachingTest < ActionController::TestCase
     @controller.params = @params
     @controller.request = @request
     @controller.response = @response
+
+    @m1v1 = ModelWithKeyAndVersion.new("model/1", "1")
+    @m1v2 = ModelWithKeyAndVersion.new("model/1", "2")
+    @m2v1 = ModelWithKeyAndVersion.new("model/2", "1")
+    @m2v2 = ModelWithKeyAndVersion.new("model/2", "2")
   end
 
   def test_fragment_cache_key
-    assert_equal "views/what a key", @controller.fragment_cache_key("what a key")
-    assert_equal "views/test.host/fragment_caching_test/some_action",
-                  @controller.fragment_cache_key(controller: "fragment_caching_test", action: "some_action")
+    assert_deprecated do
+      assert_equal "views/what a key", @controller.fragment_cache_key("what a key")
+      assert_equal "views/test.host/fragment_caching_test/some_action",
+        @controller.fragment_cache_key(controller: "fragment_caching_test", action: "some_action")
+    end
+  end
+
+  def test_combined_fragment_cache_key
+    assert_equal [ :views, "what a key" ], @controller.combined_fragment_cache_key("what a key")
+    assert_equal [ :views, "test.host/fragment_caching_test/some_action" ],
+      @controller.combined_fragment_cache_key(controller: "fragment_caching_test", action: "some_action")
   end
 
   def test_read_fragment_with_caching_enabled
@@ -72,6 +83,12 @@ class FragmentCachingTest < ActionController::TestCase
     assert_nil @controller.read_fragment("name")
   end
 
+  def test_read_fragment_with_versioned_model
+    @controller.write_fragment([ "stuff", @m1v1 ], "hello")
+    assert_equal "hello", @controller.read_fragment([ "stuff", @m1v1 ])
+    assert_nil @controller.read_fragment([ "stuff", @m1v2 ])
+  end
+
   def test_fragment_exist_with_caching_enabled
     @store.write("views/name", "value")
     assert @controller.fragment_exist?("name")
@@ -198,7 +215,7 @@ CACHED
     assert_equal expected_body, @response.body
 
     assert_equal "This bit's fragment cached",
-      @store.read("views/test.host/functional_caching/fragment_cached/#{template_digest("functional_caching/fragment_cached")}")
+      @store.read("views/functional_caching/fragment_cached:#{template_digest("functional_caching/fragment_cached")}/fragment")
   end
 
   def test_fragment_caching_in_partials
@@ -207,7 +224,7 @@ CACHED
     assert_match(/Old fragment caching in a partial/, @response.body)
 
     assert_match("Old fragment caching in a partial",
-      @store.read("views/test.host/functional_caching/html_fragment_cached_with_partial/#{template_digest("functional_caching/_partial")}"))
+      @store.read("views/functional_caching/_partial:#{template_digest("functional_caching/_partial")}/test.host/functional_caching/html_fragment_cached_with_partial"))
   end
 
   def test_skipping_fragment_cache_digesting
@@ -237,7 +254,7 @@ CACHED
     assert_match(/Some inline content/, @response.body)
     assert_match(/Some cached content/, @response.body)
     assert_match("Some cached content",
-      @store.read("views/test.host/functional_caching/inline_fragment_cached/#{template_digest("functional_caching/inline_fragment_cached")}"))
+      @store.read("views/functional_caching/inline_fragment_cached:#{template_digest("functional_caching/inline_fragment_cached")}/test.host/functional_caching/inline_fragment_cached"))
   end
 
   def test_fragment_cache_instrumentation
@@ -264,7 +281,7 @@ CACHED
     assert_equal expected_body, @response.body
 
     assert_equal "<p>ERB</p>",
-      @store.read("views/test.host/functional_caching/formatted_fragment_cached/#{template_digest("functional_caching/formatted_fragment_cached")}")
+      @store.read("views/functional_caching/formatted_fragment_cached:#{template_digest("functional_caching/formatted_fragment_cached")}/fragment")
   end
 
   def test_xml_formatted_fragment_caching
@@ -275,7 +292,7 @@ CACHED
     assert_equal expected_body, @response.body
 
     assert_equal "  <p>Builder</p>\n",
-      @store.read("views/test.host/functional_caching/formatted_fragment_cached/#{template_digest("functional_caching/formatted_fragment_cached")}")
+      @store.read("views/functional_caching/formatted_fragment_cached:#{template_digest("functional_caching/formatted_fragment_cached")}/fragment")
   end
 
   def test_fragment_caching_with_variant
@@ -286,7 +303,7 @@ CACHED
     assert_equal expected_body, @response.body
 
     assert_equal "<p>PHONE</p>",
-      @store.read("views/test.host/functional_caching/formatted_fragment_cached_with_variant/#{template_digest("functional_caching/formatted_fragment_cached_with_variant")}")
+      @store.read("views/functional_caching/formatted_fragment_cached_with_variant:#{template_digest("functional_caching/formatted_fragment_cached_with_variant")}/fragment")
   end
 
   private
@@ -412,7 +429,7 @@ class CollectionCacheTest < ActionController::TestCase
   def test_collection_fetches_cached_views
     get :index
     assert_equal 1, @controller.partial_rendered_times
-    assert_customer_cached "david/1", "david, 1"
+    assert_match "david, 1", ActionView::PartialRenderer.collection_cache.read("views/customers/_customer:7c228ab609f0baf0b1f2367469210937/david/1")
 
     get :index
     assert_equal 1, @controller.partial_rendered_times
@@ -444,14 +461,8 @@ class CollectionCacheTest < ActionController::TestCase
 
   def test_caching_with_callable_cache_key
     get :index_with_callable_cache_key
-    assert_customer_cached "cached_david", "david, 1"
+    assert_match "david, 1", ActionView::PartialRenderer.collection_cache.read("views/customers/_customer:7c228ab609f0baf0b1f2367469210937/cached_david")
   end
-
-  private
-    def assert_customer_cached(key, content)
-      assert_match content,
-        ActionView::PartialRenderer.collection_cache.read("views/#{key}/7c228ab609f0baf0b1f2367469210937")
-    end
 end
 
 class FragmentCacheKeyTestController < CachingController
@@ -470,11 +481,21 @@ class FragmentCacheKeyTest < ActionController::TestCase
     @controller.cache_store = @store
   end
 
-  def test_fragment_cache_key
+  def test_combined_fragment_cache_key
     @controller.account_id = "123"
-    assert_equal "views/v1/123/what a key", @controller.fragment_cache_key("what a key")
+    assert_equal [ :views, "v1", "123", "what a key" ], @controller.combined_fragment_cache_key("what a key")
 
     @controller.account_id = nil
-    assert_equal "views/v1//what a key", @controller.fragment_cache_key("what a key")
+    assert_equal [ :views, "v1", "what a key" ], @controller.combined_fragment_cache_key("what a key")
+  end
+
+  def test_combined_fragment_cache_key_with_envs
+    ENV["RAILS_APP_VERSION"] = "55"
+    assert_equal [ :views, "55", "v1", "what a key" ], @controller.combined_fragment_cache_key("what a key")
+
+    ENV["RAILS_CACHE_ID"] = "66"
+    assert_equal [ :views, "66", "v1", "what a key" ], @controller.combined_fragment_cache_key("what a key")
+  ensure
+    ENV["RAILS_CACHE_ID"] = ENV["RAILS_APP_VERSION"] = nil
   end
 end
diff --git a/actionpack/test/controller/helper_test.rb b/actionpack/test/controller/helper_test.rb
index 4c6a772062..03dbd63614 100644
--- a/actionpack/test/controller/helper_test.rb
+++ b/actionpack/test/controller/helper_test.rb
@@ -1,6 +1,6 @@
 require "abstract_unit"
 
-ActionController::Base.helpers_path = File.expand_path("../../fixtures/helpers", __FILE__)
+ActionController::Base.helpers_path = File.expand_path("../fixtures/helpers", __dir__)
 
 module Fun
   class GamesController < ActionController::Base
@@ -48,7 +48,7 @@ end
 
 class HelpersPathsController < ActionController::Base
   paths = ["helpers2_pack", "helpers1_pack"].map do |path|
-    File.join(File.expand_path("../../fixtures", __FILE__), path)
+    File.join(File.expand_path("../fixtures", __dir__), path)
   end
   $:.unshift(*paths)
 
@@ -61,7 +61,7 @@ class HelpersPathsController < ActionController::Base
 end
 
 class HelpersTypoController < ActionController::Base
-  path = File.expand_path("../../fixtures/helpers_typo", __FILE__)
+  path = File.expand_path("../fixtures/helpers_typo", __dir__)
   $:.unshift(path)
   self.helpers_path = path
 end
@@ -178,7 +178,7 @@ class HelperTest < ActiveSupport::TestCase
   end
 
   def test_all_helpers_with_alternate_helper_dir
-    @controller_class.helpers_path = File.expand_path("../../fixtures/alternate_helpers", __FILE__)
+    @controller_class.helpers_path = File.expand_path("../fixtures/alternate_helpers", __dir__)
 
     # Reload helpers
     @controller_class._helpers = Module.new
diff --git a/actionpack/test/controller/integration_test.rb b/actionpack/test/controller/integration_test.rb
index 57f58fd835..72163ccd5e 100644
--- a/actionpack/test/controller/integration_test.rb
+++ b/actionpack/test/controller/integration_test.rb
@@ -1091,7 +1091,7 @@ class IntegrationFileUploadTest < ActionDispatch::IntegrationTest
   end
 
   def self.fixture_path
-    File.dirname(__FILE__) + "/../fixtures/multipart"
+    File.expand_path("../fixtures/multipart", __dir__)
   end
 
   routes.draw do
diff --git a/actionpack/test/controller/live_stream_test.rb b/actionpack/test/controller/live_stream_test.rb
index 581081dd07..bfb47b90d5 100644
--- a/actionpack/test/controller/live_stream_test.rb
+++ b/actionpack/test/controller/live_stream_test.rb
@@ -152,7 +152,7 @@ module ActionController
       end
 
       def write_sleep_autoload
-        path = File.join(File.dirname(__FILE__), "../fixtures")
+        path = File.expand_path("../fixtures", __dir__)
         ActiveSupport::Dependencies.autoload_paths << path
 
         response.headers["Content-Type"] = "text/event-stream"
diff --git a/actionpack/test/controller/mime/accept_format_test.rb b/actionpack/test/controller/mime/accept_format_test.rb
index a22fa39051..d1c4dbfef7 100644
--- a/actionpack/test/controller/mime/accept_format_test.rb
+++ b/actionpack/test/controller/mime/accept_format_test.rb
@@ -29,7 +29,7 @@ class StarStarMimeControllerTest < ActionController::TestCase
 end
 
 class AbstractPostController < ActionController::Base
-  self.view_paths = File.dirname(__FILE__) + "/../../fixtures/post_test/"
+  self.view_paths = File.expand_path("../../fixtures/post_test", __dir__)
 end
 
 # For testing layouts which are set automatically
diff --git a/actionpack/test/controller/new_base/render_file_test.rb b/actionpack/test/controller/new_base/render_file_test.rb
index 6d651e0104..4491dd96ed 100644
--- a/actionpack/test/controller/new_base/render_file_test.rb
+++ b/actionpack/test/controller/new_base/render_file_test.rb
@@ -2,15 +2,15 @@ require "abstract_unit"
 
 module RenderFile
   class BasicController < ActionController::Base
-    self.view_paths = File.dirname(__FILE__)
+    self.view_paths = __dir__
 
     def index
-      render file: File.join(File.dirname(__FILE__), *%w[.. .. fixtures test hello_world])
+      render file: File.expand_path("../../fixtures/test/hello_world", __dir__)
     end
 
     def with_instance_variables
       @secret = "in the sauce"
-      render file: File.join(File.dirname(__FILE__), "../../fixtures/test/render_file_with_ivar")
+      render file: File.expand_path("../../fixtures/test/render_file_with_ivar", __dir__)
     end
 
     def relative_path
@@ -25,11 +25,11 @@ module RenderFile
 
     def pathname
       @secret = "in the sauce"
-      render file: Pathname.new(File.dirname(__FILE__)).join(*%w[.. .. fixtures test dot.directory render_file_with_ivar])
+      render file: Pathname.new(__dir__).join(*%w[.. .. fixtures test dot.directory render_file_with_ivar])
     end
 
     def with_locals
-      path = File.join(File.dirname(__FILE__), "../../fixtures/test/render_file_with_locals")
+      path = File.expand_path("../../fixtures/test/render_file_with_locals", __dir__)
       render file: path, locals: { secret: "in the sauce" }
     end
   end
diff --git a/actionpack/test/controller/new_base/render_implicit_action_test.rb b/actionpack/test/controller/new_base/render_implicit_action_test.rb
index 796283466a..c5fc8e15e1 100644
--- a/actionpack/test/controller/new_base/render_implicit_action_test.rb
+++ b/actionpack/test/controller/new_base/render_implicit_action_test.rb
@@ -6,7 +6,7 @@ module RenderImplicitAction
       "render_implicit_action/simple/hello_world.html.erb"     => "Hello world!",
       "render_implicit_action/simple/hyphen-ated.html.erb"     => "Hello hyphen-ated!",
       "render_implicit_action/simple/not_implemented.html.erb" => "Not Implemented"
-    ), ActionView::FileSystemResolver.new(File.expand_path("../../../controller", __FILE__))]
+    ), ActionView::FileSystemResolver.new(File.expand_path("../../controller", __dir__))]
 
     def hello_world() end
   end
diff --git a/actionpack/test/controller/render_test.rb b/actionpack/test/controller/render_test.rb
index 3a0a0a8bde..17d834d55f 100644
--- a/actionpack/test/controller/render_test.rb
+++ b/actionpack/test/controller/render_test.rb
@@ -257,7 +257,7 @@ end
 module TemplateModificationHelper
   private
     def modify_template(name)
-      path = File.expand_path("../../fixtures/#{name}.erb", __FILE__)
+      path = File.expand_path("../fixtures/#{name}.erb", __dir__)
       original = File.read(path)
       File.write(path, "#{original} Modified!")
       ActionView::LookupContext::DetailsKey.clear
@@ -287,9 +287,9 @@ class ExpiresInRenderTest < ActionController::TestCase
 
   def test_dynamic_render_with_file
     # This is extremely bad, but should be possible to do.
-    assert File.exist?(File.join(File.dirname(__FILE__), "../../test/abstract_unit.rb"))
+    assert File.exist?(File.expand_path("../../test/abstract_unit.rb", __dir__))
     response = get :dynamic_render_with_file, params: { id: '../\\../test/abstract_unit.rb' }
-    assert_equal File.read(File.join(File.dirname(__FILE__), "../../test/abstract_unit.rb")),
+    assert_equal File.read(File.expand_path("../../test/abstract_unit.rb", __dir__)),
       response.body
   end
 
@@ -306,16 +306,16 @@ class ExpiresInRenderTest < ActionController::TestCase
   end
 
   def test_dynamic_render
-    assert File.exist?(File.join(File.dirname(__FILE__), "../../test/abstract_unit.rb"))
+    assert File.exist?(File.expand_path("../../test/abstract_unit.rb", __dir__))
     assert_raises ActionView::MissingTemplate do
       get :dynamic_render, params: { id: '../\\../test/abstract_unit.rb' }
     end
   end
 
   def test_permitted_dynamic_render_file_hash
-    assert File.exist?(File.join(File.dirname(__FILE__), "../../test/abstract_unit.rb"))
+    assert File.exist?(File.expand_path("../../test/abstract_unit.rb", __dir__))
     response = get :dynamic_render_permit, params: { id: { file: '../\\../test/abstract_unit.rb' } }
-    assert_equal File.read(File.join(File.dirname(__FILE__), "../../test/abstract_unit.rb")),
+    assert_equal File.read(File.expand_path("../../test/abstract_unit.rb", __dir__)),
       response.body
   end
 
diff --git a/actionpack/test/controller/send_file_test.rb b/actionpack/test/controller/send_file_test.rb
index 9e6b975fe2..e265c6c49c 100644
--- a/actionpack/test/controller/send_file_test.rb
+++ b/actionpack/test/controller/send_file_test.rb
@@ -2,7 +2,7 @@ require "abstract_unit"
 
 module TestFileUtils
   def file_name() File.basename(__FILE__) end
-  def file_path() File.expand_path(__FILE__) end
+  def file_path() __FILE__ end
   def file_data() @data ||= File.open(file_path, "rb") { |f| f.read } end
 end
 
diff --git a/actionpack/test/controller/test_case_test.rb b/actionpack/test/controller/test_case_test.rb
index 3a4307b64b..677e2ddded 100644
--- a/actionpack/test/controller/test_case_test.rb
+++ b/actionpack/test/controller/test_case_test.rb
@@ -122,7 +122,7 @@ XML
     end
 
     def test_send_file
-      send_file(File.expand_path(__FILE__))
+      send_file(__FILE__)
     end
 
     def redirect_to_same_controller
@@ -780,7 +780,7 @@ XML
     end
   end
 
-  FILES_DIR = File.dirname(__FILE__) + "/../fixtures/multipart"
+  FILES_DIR = File.expand_path("../fixtures/multipart", __dir__)
 
   READ_BINARY = "rb:binary"
   READ_PLAIN = "r:binary"
@@ -855,7 +855,7 @@ XML
   end
 
   def test_fixture_file_upload_ignores_fixture_path_given_full_path
-    TestCaseTest.stub :fixture_path, File.dirname(__FILE__) do
+    TestCaseTest.stub :fixture_path, __dir__ do
       uploaded_file = fixture_file_upload("#{FILES_DIR}/ruby_on_rails.jpg", "image/jpg")
       assert_equal File.open("#{FILES_DIR}/ruby_on_rails.jpg", READ_PLAIN).read, uploaded_file.read
     end
diff --git a/actionpack/test/dispatch/cookies_test.rb b/actionpack/test/dispatch/cookies_test.rb
index 664faa31bb..e5646de82e 100644
--- a/actionpack/test/dispatch/cookies_test.rb
+++ b/actionpack/test/dispatch/cookies_test.rb
@@ -288,8 +288,7 @@ class CookiesTest < ActionController::TestCase
     @request.env["action_dispatch.key_generator"] = ActiveSupport::KeyGenerator.new(SALT, iterations: 2)
 
     @request.env["action_dispatch.signed_cookie_salt"] =
-      @request.env["action_dispatch.encrypted_cookie_salt"] =
-      @request.env["action_dispatch.encrypted_signed_cookie_salt"] = SALT
+      @request.env["action_dispatch.authenticated_encrypted_cookie_salt"] = SALT
 
     @request.host = "www.nextangle.com"
   end
@@ -531,9 +530,7 @@ class CookiesTest < ActionController::TestCase
     get :set_encrypted_cookie
     cookies = @controller.send :cookies
     assert_not_equal "bar", cookies[:foo]
-    assert_raise TypeError do
-      cookies.signed[:foo]
-    end
+    assert_nil cookies.signed[:foo]
     assert_equal "bar", cookies.encrypted[:foo]
   end
 
@@ -542,9 +539,7 @@ class CookiesTest < ActionController::TestCase
     get :set_encrypted_cookie
     cookies = @controller.send :cookies
     assert_not_equal "bar", cookies[:foo]
-    assert_raises TypeError do
-      cookies.signed[:foo]
-    end
+    assert_nil cookies.signed[:foo]
     assert_equal "bar", cookies.encrypted[:foo]
   end
 
@@ -553,9 +548,7 @@ class CookiesTest < ActionController::TestCase
     get :set_encrypted_cookie
     cookies = @controller.send :cookies
     assert_not_equal "bar", cookies[:foo]
-    assert_raises ::JSON::ParserError do
-      cookies.signed[:foo]
-    end
+    assert_nil cookies.signed[:foo]
     assert_equal "bar", cookies.encrypted[:foo]
   end
 
@@ -564,9 +557,7 @@ class CookiesTest < ActionController::TestCase
     get :set_wrapped_encrypted_cookie
     cookies = @controller.send :cookies
     assert_not_equal "wrapped: bar", cookies[:foo]
-    assert_raises ::JSON::ParserError do
-      cookies.signed[:foo]
-    end
+    assert_nil cookies.signed[:foo]
     assert_equal "wrapped: bar", cookies.encrypted[:foo]
   end
 
@@ -577,38 +568,16 @@ class CookiesTest < ActionController::TestCase
     assert_equal "bar was dumped and loaded", cookies.encrypted[:foo]
   end
 
-  def test_encrypted_cookie_using_custom_digest
-    @request.env["action_dispatch.cookies_digest"] = "SHA256"
-    get :set_encrypted_cookie
-    cookies = @controller.send :cookies
-    assert_not_equal "bar", cookies[:foo]
-    assert_equal "bar", cookies.encrypted[:foo]
-
-    sign_secret = @request.env["action_dispatch.key_generator"].generate_key(@request.env["action_dispatch.encrypted_signed_cookie_salt"])
-
-    sha1_verifier   = ActiveSupport::MessageVerifier.new(sign_secret, serializer: ActiveSupport::MessageEncryptor::NullSerializer, digest: "SHA1")
-    sha256_verifier = ActiveSupport::MessageVerifier.new(sign_secret, serializer: ActiveSupport::MessageEncryptor::NullSerializer, digest: "SHA256")
-
-    assert_raises(ActiveSupport::MessageVerifier::InvalidSignature) do
-      sha1_verifier.verify(cookies[:foo])
-    end
-
-    assert_nothing_raised do
-      sha256_verifier.verify(cookies[:foo])
-    end
-  end
-
   def test_encrypted_cookie_using_hybrid_serializer_can_migrate_marshal_dumped_value_to_json
     @request.env["action_dispatch.cookies_serializer"] = :hybrid
 
-    key_generator = @request.env["action_dispatch.key_generator"]
-    encrypted_cookie_salt = @request.env["action_dispatch.encrypted_cookie_salt"]
-    encrypted_signed_cookie_salt = @request.env["action_dispatch.encrypted_signed_cookie_salt"]
-    secret = key_generator.generate_key(encrypted_cookie_salt)
-    sign_secret = key_generator.generate_key(encrypted_signed_cookie_salt)
+    cipher = "aes-256-gcm"
+    salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
+    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: Marshal)
 
-    marshal_value = ActiveSupport::MessageEncryptor.new(secret[0, ActiveSupport::MessageEncryptor.key_len], sign_secret, serializer: Marshal).encrypt_and_sign("bar")
-    @request.headers["Cookie"] = "foo=#{marshal_value}"
+    marshal_value = encryptor.encrypt_and_sign("bar")
+    @request.headers["Cookie"] = "foo=#{::Rack::Utils.escape marshal_value}"
 
     get :get_encrypted_cookie
 
@@ -616,40 +585,28 @@ class CookiesTest < ActionController::TestCase
     assert_not_equal "bar", cookies[:foo]
     assert_equal "bar", cookies.encrypted[:foo]
 
-    encryptor = ActiveSupport::MessageEncryptor.new(secret[0, ActiveSupport::MessageEncryptor.key_len], sign_secret, serializer: JSON)
-    assert_equal "bar", encryptor.decrypt_and_verify(@response.cookies["foo"])
+    json_encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: JSON)
+    assert_not_nil @response.cookies["foo"]
+    assert_equal "bar", json_encryptor.decrypt_and_verify(@response.cookies["foo"])
   end
 
   def test_encrypted_cookie_using_hybrid_serializer_can_read_from_json_dumped_value
     @request.env["action_dispatch.cookies_serializer"] = :hybrid
 
-    key_generator = @request.env["action_dispatch.key_generator"]
-    encrypted_cookie_salt = @request.env["action_dispatch.encrypted_cookie_salt"]
-    encrypted_signed_cookie_salt = @request.env["action_dispatch.encrypted_signed_cookie_salt"]
-    secret = key_generator.generate_key(encrypted_cookie_salt)
-    sign_secret = key_generator.generate_key(encrypted_signed_cookie_salt)
-    json_value = ActiveSupport::MessageEncryptor.new(secret[0, ActiveSupport::MessageEncryptor.key_len], sign_secret, serializer: JSON).encrypt_and_sign("bar")
-    @request.headers["Cookie"] = "foo=#{json_value}"
-
-    get :get_encrypted_cookie
+    cipher = "aes-256-gcm"
+    salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
+    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: JSON)
 
-    cookies = @controller.send :cookies
-    assert_not_equal "bar", cookies[:foo]
-    assert_equal "bar", cookies.encrypted[:foo]
-
-    assert_nil @response.cookies["foo"]
-  end
-
-  def test_compat_encrypted_cookie_using_64_byte_key
-    # Cookie generated with 64 bytes secret
-    message = ["566d4e75536d686e633246564e6b493062557079626c566d51574d30515430394c53315665564a694e4563786555744f57537454576b396a5a31566a626e52525054303d2d2d34663234333330623130623261306163363562316266323335396164666364613564643134623131"].pack("H*")
-    @request.headers["Cookie"] = "foo=#{message}"
+    json_value = encryptor.encrypt_and_sign("bar")
+    @request.headers["Cookie"] = "foo=#{::Rack::Utils.escape json_value}"
 
     get :get_encrypted_cookie
 
     cookies = @controller.send :cookies
     assert_not_equal "bar", cookies[:foo]
     assert_equal "bar", cookies.encrypted[:foo]
+
     assert_nil @response.cookies["foo"]
   end
 
@@ -813,10 +770,10 @@ class CookiesTest < ActionController::TestCase
 
     assert_equal "bar", @controller.send(:cookies).encrypted[:foo]
 
-    key_generator = @request.env["action_dispatch.key_generator"]
-    secret = key_generator.generate_key(@request.env["action_dispatch.encrypted_cookie_salt"])
-    sign_secret = key_generator.generate_key(@request.env["action_dispatch.encrypted_signed_cookie_salt"])
-    encryptor = ActiveSupport::MessageEncryptor.new(secret[0, ActiveSupport::MessageEncryptor.key_len], sign_secret)
+    cipher = "aes-256-gcm"
+    salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
+    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: Marshal)
     assert_equal "bar", encryptor.decrypt_and_verify(@response.cookies["foo"])
   end
 
@@ -842,8 +799,6 @@ class CookiesTest < ActionController::TestCase
     @request.env["action_dispatch.cookies_serializer"] = :json
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
     @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-    @request.env["action_dispatch.encrypted_cookie_salt"] = "4433796b79d99a7735553e316522acee"
-    @request.env["action_dispatch.encrypted_signed_cookie_salt"] = "00646eb40062e1b1deff205a27cd30f9"
 
     legacy_value = ActiveSupport::MessageVerifier.new("b3c631c314c0bbca50c1b2843150fe33", serializer: JSON).generate("bar")
 
@@ -852,10 +807,10 @@ class CookiesTest < ActionController::TestCase
 
     assert_equal "bar", @controller.send(:cookies).encrypted[:foo]
 
-    key_generator = @request.env["action_dispatch.key_generator"]
-    secret = key_generator.generate_key(@request.env["action_dispatch.encrypted_cookie_salt"])
-    sign_secret = key_generator.generate_key(@request.env["action_dispatch.encrypted_signed_cookie_salt"])
-    encryptor = ActiveSupport::MessageEncryptor.new(secret[0, ActiveSupport::MessageEncryptor.key_len], sign_secret, serializer: JSON)
+    cipher = "aes-256-gcm"
+    salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
+    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: JSON)
     assert_equal "bar", encryptor.decrypt_and_verify(@response.cookies["foo"])
   end
 
@@ -881,8 +836,6 @@ class CookiesTest < ActionController::TestCase
     @request.env["action_dispatch.cookies_serializer"] = :hybrid
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
     @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-    @request.env["action_dispatch.encrypted_cookie_salt"] = "4433796b79d99a7735553e316522acee"
-    @request.env["action_dispatch.encrypted_signed_cookie_salt"] = "00646eb40062e1b1deff205a27cd30f9"
 
     legacy_value = ActiveSupport::MessageVerifier.new("b3c631c314c0bbca50c1b2843150fe33", serializer: JSON).generate("bar")
 
@@ -891,10 +844,10 @@ class CookiesTest < ActionController::TestCase
 
     assert_equal "bar", @controller.send(:cookies).encrypted[:foo]
 
-    key_generator = @request.env["action_dispatch.key_generator"]
-    secret = key_generator.generate_key(@request.env["action_dispatch.encrypted_cookie_salt"])
-    sign_secret = key_generator.generate_key(@request.env["action_dispatch.encrypted_signed_cookie_salt"])
-    encryptor = ActiveSupport::MessageEncryptor.new(secret[0, ActiveSupport::MessageEncryptor.key_len], sign_secret, serializer: JSON)
+    cipher = "aes-256-gcm"
+    salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
+    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: JSON)
     assert_equal "bar", encryptor.decrypt_and_verify(@response.cookies["foo"])
   end
 
@@ -920,8 +873,6 @@ class CookiesTest < ActionController::TestCase
     @request.env["action_dispatch.cookies_serializer"] = :hybrid
     @request.env["action_dispatch.secret_token"] = "b3c631c314c0bbca50c1b2843150fe33"
     @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
-    @request.env["action_dispatch.encrypted_cookie_salt"] = "4433796b79d99a7735553e316522acee"
-    @request.env["action_dispatch.encrypted_signed_cookie_salt"] = "00646eb40062e1b1deff205a27cd30f9"
 
     legacy_value = ActiveSupport::MessageVerifier.new("b3c631c314c0bbca50c1b2843150fe33").generate("bar")
 
@@ -930,10 +881,10 @@ class CookiesTest < ActionController::TestCase
 
     assert_equal "bar", @controller.send(:cookies).encrypted[:foo]
 
-    key_generator = @request.env["action_dispatch.key_generator"]
-    secret = key_generator.generate_key(@request.env["action_dispatch.encrypted_cookie_salt"])
-    sign_secret = key_generator.generate_key(@request.env["action_dispatch.encrypted_signed_cookie_salt"])
-    encryptor = ActiveSupport::MessageEncryptor.new(secret[0, ActiveSupport::MessageEncryptor.key_len], sign_secret, serializer: JSON)
+    cipher = "aes-256-gcm"
+    salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
+    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: JSON)
     assert_equal "bar", encryptor.decrypt_and_verify(@response.cookies["foo"])
   end
 
@@ -959,6 +910,89 @@ class CookiesTest < ActionController::TestCase
     assert_nil @response.cookies["foo"]
   end
 
+  def test_legacy_hmac_aes_cbc_encrypted_marshal_cookie_is_upgraded_to_authenticated_encrypted_cookie
+    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
+
+    @request.env["action_dispatch.encrypted_cookie_salt"] =
+      @request.env["action_dispatch.encrypted_signed_cookie_salt"] = SALT
+
+    key_generator = @request.env["action_dispatch.key_generator"]
+    encrypted_cookie_salt = @request.env["action_dispatch.encrypted_cookie_salt"]
+    encrypted_signed_cookie_salt = @request.env["action_dispatch.encrypted_signed_cookie_salt"]
+    secret = key_generator.generate_key(encrypted_cookie_salt)
+    sign_secret = key_generator.generate_key(encrypted_signed_cookie_salt)
+    marshal_value = ActiveSupport::MessageEncryptor.new(secret[0, ActiveSupport::MessageEncryptor.key_len], sign_secret, serializer: Marshal).encrypt_and_sign("bar")
+
+    @request.headers["Cookie"] = "foo=#{marshal_value}"
+
+    get :get_encrypted_cookie
+
+    cookies = @controller.send :cookies
+    assert_not_equal "bar", cookies[:foo]
+    assert_equal "bar", cookies.encrypted[:foo]
+
+    aead_cipher = "aes-256-gcm"
+    aead_salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
+    aead_secret = key_generator.generate_key(aead_salt)[0, ActiveSupport::MessageEncryptor.key_len(aead_cipher)]
+    aead_encryptor = ActiveSupport::MessageEncryptor.new(aead_secret, cipher: aead_cipher, serializer: Marshal)
+
+    assert_equal "bar", aead_encryptor.decrypt_and_verify(@response.cookies["foo"])
+  end
+
+  def test_legacy_hmac_aes_cbc_encrypted_json_cookie_is_upgraded_to_authenticated_encrypted_cookie
+    @request.env["action_dispatch.cookies_serializer"] = :json
+    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
+
+    @request.env["action_dispatch.encrypted_cookie_salt"] =
+      @request.env["action_dispatch.encrypted_signed_cookie_salt"] = SALT
+
+    key_generator = @request.env["action_dispatch.key_generator"]
+    encrypted_cookie_salt = @request.env["action_dispatch.encrypted_cookie_salt"]
+    encrypted_signed_cookie_salt = @request.env["action_dispatch.encrypted_signed_cookie_salt"]
+    secret = key_generator.generate_key(encrypted_cookie_salt)
+    sign_secret = key_generator.generate_key(encrypted_signed_cookie_salt)
+    marshal_value = ActiveSupport::MessageEncryptor.new(secret[0, ActiveSupport::MessageEncryptor.key_len], sign_secret, serializer: JSON).encrypt_and_sign("bar")
+
+    @request.headers["Cookie"] = "foo=#{marshal_value}"
+
+    get :get_encrypted_cookie
+
+    cookies = @controller.send :cookies
+    assert_not_equal "bar", cookies[:foo]
+    assert_equal "bar", cookies.encrypted[:foo]
+
+    aead_cipher = "aes-256-gcm"
+    aead_salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
+    aead_secret = key_generator.generate_key(aead_salt)[0, ActiveSupport::MessageEncryptor.key_len(aead_cipher)]
+    aead_encryptor = ActiveSupport::MessageEncryptor.new(aead_secret, cipher: aead_cipher, serializer: JSON)
+
+    assert_equal "bar", aead_encryptor.decrypt_and_verify(@response.cookies["foo"])
+  end
+
+  def test_legacy_hmac_aes_cbc_encrypted_cookie_using_64_byte_key_is_upgraded_to_authenticated_encrypted_cookie
+    @request.env["action_dispatch.secret_key_base"] = "c3b95688f35581fad38df788add315ff"
+
+    @request.env["action_dispatch.encrypted_cookie_salt"] =
+      @request.env["action_dispatch.encrypted_signed_cookie_salt"] = SALT
+
+    # Cookie generated with 64 bytes secret
+    message = ["566d4e75536d686e633246564e6b493062557079626c566d51574d30515430394c53315665564a694e4563786555744f57537454576b396a5a31566a626e52525054303d2d2d34663234333330623130623261306163363562316266323335396164666364613564643134623131"].pack("H*")
+    @request.headers["Cookie"] = "foo=#{message}"
+
+    get :get_encrypted_cookie
+
+    cookies = @controller.send :cookies
+    assert_not_equal "bar", cookies[:foo]
+    assert_equal "bar", cookies.encrypted[:foo]
+    cipher = "aes-256-gcm"
+
+    salt = @request.env["action_dispatch.authenticated_encrypted_cookie_salt"]
+    secret = @request.env["action_dispatch.key_generator"].generate_key(salt)[0, ActiveSupport::MessageEncryptor.key_len(cipher)]
+    encryptor = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: Marshal)
+
+    assert_equal "bar", encryptor.decrypt_and_verify(@response.cookies["foo"])
+  end
+
   def test_cookie_with_all_domain_option
     get :set_cookie_with_domain
     assert_response :success
diff --git a/actionpack/test/dispatch/request/multipart_params_parsing_test.rb b/actionpack/test/dispatch/request/multipart_params_parsing_test.rb
index 01c5ff1429..e7e8c82974 100644
--- a/actionpack/test/dispatch/request/multipart_params_parsing_test.rb
+++ b/actionpack/test/dispatch/request/multipart_params_parsing_test.rb
@@ -21,7 +21,7 @@ class MultipartParamsParsingTest < ActionDispatch::IntegrationTest
     end
   end
 
-  FIXTURE_PATH = File.dirname(__FILE__) + "/../../fixtures/multipart"
+  FIXTURE_PATH = File.expand_path("../../fixtures/multipart", __dir__)
 
   def teardown
     TestController.last_request_parameters = nil
diff --git a/actionpack/test/dispatch/request/session_test.rb b/actionpack/test/dispatch/request/session_test.rb
index 311b80ea0a..228135c547 100644
--- a/actionpack/test/dispatch/request/session_test.rb
+++ b/actionpack/test/dispatch/request/session_test.rb
@@ -54,6 +54,11 @@ module ActionDispatch
         assert_equal %w[rails adequate], s.keys
       end
 
+      def test_keys_with_deferred_loading
+        s = Session.create(store_with_data, req, {})
+        assert_equal %w[sample_key], s.keys
+      end
+
       def test_values
         s = Session.create(store, req, {})
         s["rails"] = "ftw"
@@ -61,6 +66,11 @@ module ActionDispatch
         assert_equal %w[ftw awesome], s.values
       end
 
+      def test_values_with_deferred_loading
+        s = Session.create(store_with_data, req, {})
+        assert_equal %w[sample_value], s.values
+      end
+
       def test_clear
         s = Session.create(store, req, {})
         s["rails"] = "ftw"
@@ -113,6 +123,14 @@ module ActionDispatch
             def delete_session(env, id, options); 123; end
           }.new
         end
+
+        def store_with_data
+          Class.new {
+            def load_session(env); [1, { "sample_key" => "sample_value" }]; end
+            def session_exists?(env); true; end
+            def delete_session(env, id, options); 123; end
+          }.new
+        end
     end
 
     class SessionIntegrationTest < ActionDispatch::IntegrationTest
diff --git a/actionpack/test/dispatch/request/url_encoded_params_parsing_test.rb b/actionpack/test/dispatch/request/url_encoded_params_parsing_test.rb
index 1169bf0cdb..6721a388c1 100644
--- a/actionpack/test/dispatch/request/url_encoded_params_parsing_test.rb
+++ b/actionpack/test/dispatch/request/url_encoded_params_parsing_test.rb
@@ -107,7 +107,7 @@ class UrlEncodedParamsParsingTest < ActionDispatch::IntegrationTest
     query = [
       "customers[boston][first][name]=David",
       "something_else=blah",
-      "logo=#{File.expand_path(__FILE__)}"
+      "logo=#{__FILE__}"
     ].join("&")
     expected = {
       "customers" => {
@@ -118,7 +118,7 @@ class UrlEncodedParamsParsingTest < ActionDispatch::IntegrationTest
         }
       },
       "something_else" => "blah",
-      "logo" => File.expand_path(__FILE__),
+      "logo" => __FILE__,
     }
     assert_parses expected, query
   end
diff --git a/actionpack/test/dispatch/system_testing/driver_test.rb b/actionpack/test/dispatch/system_testing/driver_test.rb
index 814e1d707b..4a1b971da5 100644
--- a/actionpack/test/dispatch/system_testing/driver_test.rb
+++ b/actionpack/test/dispatch/system_testing/driver_test.rb
@@ -15,7 +15,21 @@ class DriverTest < ActiveSupport::TestCase
     assert_equal ({ url: "http://example.com/wd/hub" }), driver.instance_variable_get(:@options)
   end
 
-  test "selenium? returns false if driver is poltergeist" do
-    assert_not ActionDispatch::SystemTesting::Driver.new(:poltergeist).send(:selenium?)
+  test "initializing the driver with a poltergeist" do
+    driver = ActionDispatch::SystemTesting::Driver.new(:poltergeist, screen_size: [1400, 1400], options: { js_errors: false })
+    assert_equal :poltergeist, driver.instance_variable_get(:@name)
+    assert_equal [1400, 1400], driver.instance_variable_get(:@screen_size)
+    assert_equal ({ js_errors: false }), driver.instance_variable_get(:@options)
+  end
+
+  test "initializing the driver with a webkit" do
+    driver = ActionDispatch::SystemTesting::Driver.new(:webkit, screen_size: [1400, 1400], options: { skip_image_loading: true })
+    assert_equal :webkit, driver.instance_variable_get(:@name)
+    assert_equal [1400, 1400], driver.instance_variable_get(:@screen_size)
+    assert_equal ({ skip_image_loading: true }), driver.instance_variable_get(:@options)
+  end
+
+  test "rack_test? returns false if driver is poltergeist" do
+    assert_not ActionDispatch::SystemTesting::Driver.new(:poltergeist).send(:rack_test?)
   end
 end
diff --git a/actionpack/test/dispatch/system_testing/system_test_case_test.rb b/actionpack/test/dispatch/system_testing/system_test_case_test.rb
index 33d98f924f..8f90e45f5f 100644
--- a/actionpack/test/dispatch/system_testing/system_test_case_test.rb
+++ b/actionpack/test/dispatch/system_testing/system_test_case_test.rb
@@ -19,3 +19,15 @@ class SetDriverToSeleniumTest < DrivenBySeleniumWithChrome
     assert_equal :selenium, Capybara.current_driver
   end
 end
+
+class SetHostTest < DrivenByRackTest
+  test "sets default host" do
+    assert_equal "http://127.0.0.1", Capybara.app_host
+  end
+
+  test "overrides host" do
+    host! "http://example.com"
+
+    assert_equal "http://example.com", Capybara.app_host
+  end
+end
diff --git a/actionpack/test/fixtures/functional_caching/formatted_fragment_cached.html.erb b/actionpack/test/fixtures/functional_caching/formatted_fragment_cached.html.erb
index 9b88fa1f5a..dfcd423978 100644
--- a/actionpack/test/fixtures/functional_caching/formatted_fragment_cached.html.erb
+++ b/actionpack/test/fixtures/functional_caching/formatted_fragment_cached.html.erb
@@ -1,3 +1,3 @@
 <body>
-<%= cache do %><p>ERB</p><% end %>
+<%= cache("fragment") do %><p>ERB</p><% end %>
 </body>
diff --git a/actionpack/test/fixtures/functional_caching/formatted_fragment_cached.xml.builder b/actionpack/test/fixtures/functional_caching/formatted_fragment_cached.xml.builder
index efdcc28e0f..6599579740 100644
--- a/actionpack/test/fixtures/functional_caching/formatted_fragment_cached.xml.builder
+++ b/actionpack/test/fixtures/functional_caching/formatted_fragment_cached.xml.builder
@@ -1,5 +1,5 @@
 xml.body do
-  cache do
+  cache("fragment") do
     xml.p "Builder"
   end
 end
diff --git a/actionpack/test/fixtures/functional_caching/formatted_fragment_cached_with_variant.html+phone.erb b/actionpack/test/fixtures/functional_caching/formatted_fragment_cached_with_variant.html+phone.erb
index e523b74ae3..abf7017ce6 100644
--- a/actionpack/test/fixtures/functional_caching/formatted_fragment_cached_with_variant.html+phone.erb
+++ b/actionpack/test/fixtures/functional_caching/formatted_fragment_cached_with_variant.html+phone.erb
@@ -1,3 +1,3 @@
 <body>
-<%= cache do %><p>PHONE</p><% end %>
+<%= cache("fragment") do %><p>PHONE</p><% end %>
 </body>
diff --git a/actionpack/test/fixtures/functional_caching/fragment_cached.html.erb b/actionpack/test/fixtures/functional_caching/fragment_cached.html.erb
index fa5e6bd318..1148d83ad7 100644
--- a/actionpack/test/fixtures/functional_caching/fragment_cached.html.erb
+++ b/actionpack/test/fixtures/functional_caching/fragment_cached.html.erb
@@ -1,3 +1,3 @@
 Hello
-<%= cache do %>This bit's fragment cached<% end %>
+<%= cache "fragment" do %>This bit's fragment cached<% end %>
 <%= 'Ciao' %>
diff --git a/actionpack/test/journey/gtg/transition_table_test.rb b/actionpack/test/journey/gtg/transition_table_test.rb
index c7315c0338..889640fdd7 100644
--- a/actionpack/test/journey/gtg/transition_table_test.rb
+++ b/actionpack/test/journey/gtg/transition_table_test.rb
@@ -35,25 +35,25 @@ module ActionDispatch
 
         def test_simulate_gt
           sim = simulator_for ["/foo", "/bar"]
-          assert_match sim, "/foo"
+          assert_match_route sim, "/foo"
         end
 
         def test_simulate_gt_regexp
           sim = simulator_for [":foo"]
-          assert_match sim, "foo"
+          assert_match_route sim, "foo"
         end
 
         def test_simulate_gt_regexp_mix
           sim = simulator_for ["/get", "/:method/foo"]
-          assert_match sim, "/get"
-          assert_match sim, "/get/foo"
+          assert_match_route sim, "/get"
+          assert_match_route sim, "/get/foo"
         end
 
         def test_simulate_optional
           sim = simulator_for ["/foo(/bar)"]
-          assert_match sim, "/foo"
-          assert_match sim, "/foo/bar"
-          assert_no_match sim, "/foo/"
+          assert_match_route sim, "/foo"
+          assert_match_route sim, "/foo/bar"
+          assert_no_match_route sim, "/foo/"
         end
 
         def test_match_data
@@ -65,11 +65,11 @@ module ActionDispatch
 
           sim = GTG::Simulator.new tt
 
-          match = sim.match "/get"
-          assert_equal [paths.first], match.memos
+          memos = sim.memos "/get"
+          assert_equal [paths.first], memos
 
-          match = sim.match "/get/foo"
-          assert_equal [paths.last], match.memos
+          memos = sim.memos "/get/foo"
+          assert_equal [paths.last], memos
         end
 
         def test_match_data_ambiguous
@@ -86,8 +86,8 @@ module ActionDispatch
           builder = GTG::Builder.new ast
           sim     = GTG::Simulator.new builder.transition_table
 
-          match = sim.match "/articles/new"
-          assert_equal [paths[1], paths[3]], match.memos
+          memos = sim.memos "/articles/new"
+          assert_equal [paths[1], paths[3]], memos
         end
 
         private
@@ -109,6 +109,14 @@ module ActionDispatch
           def simulator_for(paths)
             GTG::Simulator.new tt(paths)
           end
+
+          def assert_match_route(simulator, path)
+            assert simulator.memos(path), "Simulator should match #{path}."
+          end
+
+          def assert_no_match_route(simulator, path)
+            assert_not simulator.memos(path) { nil }, "Simulator should not match #{path}."
+          end
       end
     end
   end
diff --git a/actionpack/test/lib/controller/fake_models.rb b/actionpack/test/lib/controller/fake_models.rb
index b768553e7a..ff37d85ed8 100644
--- a/actionpack/test/lib/controller/fake_models.rb
+++ b/actionpack/test/lib/controller/fake_models.rb
@@ -26,6 +26,10 @@ Customer = Struct.new(:name, :id) do
   def persisted?
     id.present?
   end
+
+  def cache_key
+    "#{name}/#{id}"
+  end
 end
 
 Post = Struct.new(:title, :author_name, :body, :secret, :persisted, :written_on, :cost) do