Restore Response#content_type to the original behavior

Since rails#35709, `Response#conten_type` returns only MIME type correctly.
It is a documented behavior that this method only returns MIME type, so
this change seems appropriate.
https://github.com/rails/rails/blob/39de7fac0507070e3c5f8b33fbad6fced84d97ed/actionpack/lib/action_dispatch/http/response.rb#L245-L249

But unfortunately, some users expect this method to return all
Content-Type that does not contain charset. This seems to be breaking
changes.

We can change this behavior with the deprecate cycle.
But, in that case, a method needs that include Content-Type with
additional parameters. And that method name is probably the
`content_type` seems to properly.

So I changed the new behavior to more appropriate another
method(`mime_type`) and restored `Response#conten_type` to the original
behavior.

The original `conten_type` method seems to have some problems with
charset parsing (it implicitly expects charset to be at the end). So I
think we should consider the appropriate behavior again later.

Fixes rails#35709.

actionpack/lib/action_controller/metal.rb

@@ -148,7 +148,7 @@ def controller_name
     attr_internal :response, :request
     delegate :session, to: "@_request"
     delegate :headers, :status=, :location=, :content_type=,
-             :status, :location, :content_type, to: "@_response"
+             :status, :location, :content_type, :media_type, to: "@_response"
 
     def initialize
       @_request = nil

actionpack/lib/action_controller/metal/mime_responds.rb

@@ -205,7 +205,7 @@ def respond_to(*mimes)
       yield collector if block_given?
 
       if format = collector.negotiate_format(request)
-        if content_type && content_type != format
+        if media_type && media_type != format
           raise ActionController::RespondToMismatchError
         end
         _process_format(format)

actionpack/lib/action_controller/metal/renderers.rb

@@ -157,7 +157,7 @@ def _render_to_body_with_renderer(options)
       json = json.to_json(options) unless json.kind_of?(String)
 
       if options[:callback].present?
-        if content_type.nil? || content_type == Mime[:json]
+        if media_type.nil? || media_type == Mime[:json]
           self.content_type = Mime[:js]
         end
 

actionpack/lib/action_controller/metal/rendering.rb

@@ -73,7 +73,7 @@ def _set_html_content_type
       end
 
       def _set_rendered_content_type(format)
-        if format && !response.content_type
+        if format && !response.media_type
           self.content_type = format.to_s
         end
       end

actionpack/lib/action_dispatch/http/response.rb

@@ -242,9 +242,8 @@ def content_type=(content_type)
       set_content_type new_header_info.mime_type, charset
     end
 
-    # Content type of response.
-    # It returns just MIME type and does NOT contain charset part.
-    def content_type
+    # Media type of response.
+    def media_type
       parsed_content_type_header.mime_type
     end
 
@@ -458,7 +457,7 @@ def munge_body_object(body)
     end
 
     def assign_default_content_type_and_charset!
-      return if content_type
+      return if media_type
 
       ct = parsed_content_type_header
       set_content_type(ct.mime_type || Mime[:html].to_s,

actionpack/lib/action_dispatch/testing/assertions.rb

@@ -14,7 +14,7 @@ module Assertions
     include Rails::Dom::Testing::Assertions
 
     def html_document
-      @html_document ||= if @response.content_type.to_s.end_with?("xml")
+      @html_document ||= if @response.media_type.to_s.end_with?("xml")
         Nokogiri::XML::Document.parse(@response.body)
       else
         Nokogiri::HTML::Document.parse(@response.body)

actionpack/lib/action_dispatch/testing/test_response.rb

@@ -19,7 +19,7 @@ def parsed_body
     end
 
     def response_parser
-      @response_parser ||= RequestEncoder.parser(content_type)
+      @response_parser ||= RequestEncoder.parser(media_type)
     end
   end
 end

actionpack/test/controller/content_type_test.rb

@@ -66,68 +66,68 @@ def setup
   def test_render_defaults
     get :render_defaults
     assert_equal "utf-8", @response.charset
-    assert_equal Mime[:text], @response.content_type
+    assert_equal Mime[:text], @response.media_type
   end
 
   def test_render_changed_charset_default
     with_default_charset "utf-16" do
       get :render_defaults
       assert_equal "utf-16", @response.charset
-      assert_equal Mime[:text], @response.content_type
+      assert_equal Mime[:text], @response.media_type
     end
   end
 
   # :ported:
   def test_content_type_from_body
     get :render_content_type_from_body
-    assert_equal Mime[:rss], @response.content_type
+    assert_equal Mime[:rss], @response.media_type
     assert_equal "utf-8", @response.charset
   end
 
   # :ported:
   def test_content_type_from_render
     get :render_content_type_from_render
-    assert_equal Mime[:rss], @response.content_type
+    assert_equal Mime[:rss], @response.media_type
     assert_equal "utf-8", @response.charset
   end
 
   # :ported:
   def test_charset_from_body
     get :render_charset_from_body
-    assert_equal Mime[:text], @response.content_type
+    assert_equal Mime[:text], @response.media_type
     assert_equal "utf-16", @response.charset
   end
 
   # :ported:
   def test_nil_charset_from_body
     get :render_nil_charset_from_body
-    assert_equal Mime[:text], @response.content_type
+    assert_equal Mime[:text], @response.media_type
     assert_equal "utf-8", @response.charset, @response.headers.inspect
   end
 
   def test_nil_default_for_erb
     with_default_charset nil do
       get :render_default_for_erb
-      assert_equal Mime[:html], @response.content_type
+      assert_equal Mime[:html], @response.media_type
       assert_nil @response.charset, @response.headers.inspect
     end
   end
 
   def test_default_for_erb
     get :render_default_for_erb
-    assert_equal Mime[:html], @response.content_type
+    assert_equal Mime[:html], @response.media_type
     assert_equal "utf-8", @response.charset
   end
 
   def test_default_for_builder
     get :render_default_for_builder
-    assert_equal Mime[:xml], @response.content_type
+    assert_equal Mime[:xml], @response.media_type
     assert_equal "utf-8", @response.charset
   end
 
   def test_change_for_builder
     get :render_change_for_builder
-    assert_equal Mime[:html], @response.content_type
+    assert_equal Mime[:html], @response.media_type
     assert_equal "utf-8", @response.charset
   end
 
@@ -148,22 +148,22 @@ class AcceptBasedContentTypeTest < ActionController::TestCase
   def test_render_default_content_types_for_respond_to
     @request.accept = Mime[:html].to_s
     get :render_default_content_types_for_respond_to
-    assert_equal Mime[:html], @response.content_type
+    assert_equal Mime[:html], @response.media_type
 
     @request.accept = Mime[:js].to_s
     get :render_default_content_types_for_respond_to
-    assert_equal Mime[:js], @response.content_type
+    assert_equal Mime[:js], @response.media_type
   end
 
   def test_render_default_content_types_for_respond_to_with_template
     @request.accept = Mime[:xml].to_s
     get :render_default_content_types_for_respond_to
-    assert_equal Mime[:xml], @response.content_type
+    assert_equal Mime[:xml], @response.media_type
   end
 
   def test_render_default_content_types_for_respond_to_with_overwrite
     @request.accept = Mime[:rss].to_s
     get :render_default_content_types_for_respond_to
-    assert_equal Mime[:xml], @response.content_type
+    assert_equal Mime[:xml], @response.media_type
   end
 end

actionpack/test/controller/integration_test.rb

@@ -522,11 +522,11 @@ def test_accept_not_overridden_when_xhr_true
     with_test_route_set do
       get "/get", headers: { "Accept" => "application/json" }, xhr: true
       assert_equal "application/json", request.accept
-      assert_equal "application/json", response.content_type
+      assert_equal "application/json", response.media_type
 
       get "/get", headers: { "HTTP_ACCEPT" => "application/json" }, xhr: true
       assert_equal "application/json", request.accept
-      assert_equal "application/json", response.content_type
+      assert_equal "application/json", response.media_type
     end
   end
 
@@ -986,7 +986,7 @@ def test_standard_json_encoding_works
   def test_encoding_as_json
     post_to_foos as: :json do
       assert_response :success
-      assert_equal "application/json", request.content_type
+      assert_equal "application/json", request.media_type
       assert_equal "application/json", request.accepts.first.to_s
       assert_equal :json, request.format.ref
       assert_equal({ "foo" => "fighters" }, request.request_parameters)
@@ -1025,7 +1025,7 @@ def test_registering_custom_encoder
     post_to_foos as: :wibble do
       assert_response :success
       assert_equal "/foos_wibble", request.path
-      assert_equal "text/wibble", request.content_type
+      assert_equal "text/wibble", request.media_type
       assert_equal "text/wibble", request.accepts.first.to_s
       assert_equal :wibble, request.format.ref
       assert_equal Hash.new, request.request_parameters # Unregistered MIME Type can't be parsed.

actionpack/test/controller/localized_templates_test.rb

@@ -43,6 +43,6 @@ def test_localized_template_has_correct_header_with_no_format_in_template_name
     I18n.locale = :it
     get :hello_world
     assert_equal "Ciao Mondo", @response.body
-    assert_equal "text/html",  @response.content_type
+    assert_equal "text/html",  @response.media_type
   end
 end

actionpack/test/controller/metal/renderers_test.rb

@@ -38,13 +38,13 @@ def test_render_json
     get :one
     assert_response :success
     assert_equal({ a: "b" }.to_json, @response.body)
-    assert_equal "application/json", @response.content_type
+    assert_equal "application/json", @response.media_type
   end
 
   def test_render_xml
     get :two
     assert_response :success
     assert_equal(" ", @response.body)
-    assert_equal "text/plain", @response.content_type
+    assert_equal "text/plain", @response.media_type
   end
 end