6 files changed, 16 insertions, 15 deletions
diff --git a/actionpack/lib/action_dispatch/http/cache.rb b/actionpack/lib/action_dispatch/http/cache.rb
index 63a3cbc90b..747d295261 100644
--- a/actionpack/lib/action_dispatch/http/cache.rb
+++ b/actionpack/lib/action_dispatch/http/cache.rb
@@ -69,17 +69,17 @@ module ActionDispatch
         end
 
         def date
-          if date_header = headers['Date']
+          if date_header = headers[DATE]
             Time.httpdate(date_header)
           end
         end
 
         def date?
-          headers.include?('Date')
+          headers.include?(DATE)
         end
 
         def date=(utc_time)
-          headers['Date'] = utc_time.httpdate
+          headers[DATE] = utc_time.httpdate
         end
 
         def etag=(etag)
@@ -89,6 +89,7 @@ module ActionDispatch
 
       private
 
+        DATE          = 'Date'.freeze
         LAST_MODIFIED = "Last-Modified".freeze
         ETAG          = "ETag".freeze
         CACHE_CONTROL = "Cache-Control".freeze
diff --git a/actionpack/lib/action_dispatch/http/filter_redirect.rb b/actionpack/lib/action_dispatch/http/filter_redirect.rb
index cd603649c3..bf79963351 100644
--- a/actionpack/lib/action_dispatch/http/filter_redirect.rb
+++ b/actionpack/lib/action_dispatch/http/filter_redirect.rb
@@ -4,7 +4,7 @@ module ActionDispatch
 
       FILTERED = '[FILTERED]'.freeze # :nodoc:
 
-      def filtered_location
+      def filtered_location # :nodoc:
         filters = location_filter
         if !filters.empty? && location_filter_match?(filters)
           FILTERED
diff --git a/actionpack/lib/action_dispatch/http/mime_type.rb b/actionpack/lib/action_dispatch/http/mime_type.rb
index 047a17937a..7e585aa244 100644
--- a/actionpack/lib/action_dispatch/http/mime_type.rb
+++ b/actionpack/lib/action_dispatch/http/mime_type.rb
@@ -45,7 +45,7 @@ module Mime
   #
   #       respond_to do |format|
   #         format.html
-  #         format.ics { render text: @post.to_ics, mime_type: Mime::Type["text/calendar"]  }
+  #         format.ics { render text: @post.to_ics, mime_type: Mime::Type.lookup("text/calendar")  }
   #         format.xml { render xml: @post }
   #       end
   #     end
diff --git a/actionpack/lib/action_dispatch/http/request.rb b/actionpack/lib/action_dispatch/http/request.rb
index cadbfc88cb..732ee67268 100644
--- a/actionpack/lib/action_dispatch/http/request.rb
+++ b/actionpack/lib/action_dispatch/http/request.rb
@@ -50,7 +50,7 @@ module ActionDispatch
       @original_fullpath = nil
       @fullpath          = nil
       @ip                = nil
-      @uuid              = nil
+      @request_id        = nil
     end
 
     def check_path_parameters!
@@ -114,7 +114,7 @@ module ActionDispatch
     end
 
     def engine_script_name(_routes) # :nodoc:
-      env["ROUTES_#{_routes.object_id}_SCRIPT_NAME"]
+      env[_routes.env_key]
     end
 
     def request_method=(request_method) #:nodoc:
@@ -249,10 +249,12 @@ module ActionDispatch
     #
     # This unique ID is useful for tracing a request from end-to-end as part of logging or debugging.
     # This relies on the rack variable set by the ActionDispatch::RequestId middleware.
-    def uuid
-      @uuid ||= env["action_dispatch.request_id"]
+    def request_id
+      @request_id ||= env["action_dispatch.request_id"]
     end
 
+    alias_method :uuid, :request_id
+
     # Returns the lowercase name of the HTTP server software.
     def server_software
       (@env['SERVER_SOFTWARE'] && /^([a-zA-Z]+)/ =~ @env['SERVER_SOFTWARE']) ? $1.downcase : nil
diff --git a/actionpack/lib/action_dispatch/http/response.rb b/actionpack/lib/action_dispatch/http/response.rb
index 4061ea71a3..a895d1ab18 100644
--- a/actionpack/lib/action_dispatch/http/response.rb
+++ b/actionpack/lib/action_dispatch/http/response.rb
@@ -113,10 +113,10 @@ module ActionDispatch # :nodoc:
     # The underlying body, as a streamable object.
     attr_reader :stream
 
-    def initialize(status = 200, header = {}, body = [])
+    def initialize(status = 200, header = {}, body = [], default_headers: self.class.default_headers)
       super()
 
-      header = merge_default_headers(header, self.class.default_headers)
+      header = merge_default_headers(header, default_headers)
 
       self.body, self.header, self.status = body, header, status
 
@@ -308,9 +308,7 @@ module ActionDispatch # :nodoc:
     end
 
     def merge_default_headers(original, default)
-      return original unless default.respond_to?(:merge)
-
-      default.merge(original)
+      default.respond_to?(:merge) ? default.merge(original) : original
     end
 
     def build_buffer(response, body)
diff --git a/actionpack/lib/action_dispatch/http/url.rb b/actionpack/lib/action_dispatch/http/url.rb
index 001b14ec97..7da6301ac4 100644
--- a/actionpack/lib/action_dispatch/http/url.rb
+++ b/actionpack/lib/action_dispatch/http/url.rb
@@ -67,7 +67,7 @@ module ActionDispatch
         end
 
         def path_for(options)
-          path  = options[:script_name].to_s.chomp("/")
+          path  = options[:script_name].to_s.chomp("/".freeze)
           path << options[:path] if options.key?(:path)
 
           add_trailing_slash(path) if options[:trailing_slash]