Change `ActionDispatch::Response#content_type` returning Content-Type header as it is

Since #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 `media_type` method.
And `Response#content_type` changed (as the method name) to return Content-Type
header as it is.

Fixes #35709.

[Rafael Mendonça França & Yuuji Yaginuma ]

1 files changed, 28 insertions, 8 deletions

diff --git a/actionpack/test/dispatch/response_test.rb b/actionpack/test/dispatch/response_test.rb
index 7758b0406a..33cf86a081 100644
--- a/actionpack/test/dispatch/response_test.rb
+++ b/actionpack/test/dispatch/response_test.rb
@@ -290,8 +290,8 @@ class ResponseTest < ActiveSupport::TestCase
     resp.to_a
 
     assert_equal("utf-16", resp.charset)
-    assert_equal(Mime[:xml], resp.content_type)
-
+    assert_equal(Mime[:xml], resp.media_type)
+    assert_equal("application/xml; charset=utf-16", resp.content_type)
     assert_equal("application/xml; charset=utf-16", resp.headers["Content-Type"])
   end
 
@@ -503,8 +503,8 @@ class ResponseIntegrationTest < ActionDispatch::IntegrationTest
     assert_response :success
 
     assert_equal("utf-16", @response.charset)
-    assert_equal(Mime[:xml], @response.content_type)
-
+    assert_equal(Mime[:xml], @response.media_type)
+    assert_equal("application/xml; charset=utf-16", @response.content_type)
     assert_equal("application/xml; charset=utf-16", @response.headers["Content-Type"])
   end
 
@@ -519,8 +519,8 @@ class ResponseIntegrationTest < ActionDispatch::IntegrationTest
     assert_response :success
 
     assert_equal("utf-16", @response.charset)
-    assert_equal(Mime[:xml], @response.content_type)
-
+    assert_equal(Mime[:xml], @response.media_type)
+    assert_equal("application/xml; charset=utf-16", @response.content_type)
     assert_equal("application/xml; charset=utf-16", @response.headers["Content-Type"])
   end
 
@@ -553,7 +553,26 @@ class ResponseIntegrationTest < ActionDispatch::IntegrationTest
     assert_response :success
 
     assert_equal("text/csv; charset=utf-16; header=present", @response.headers["Content-Type"])
-    assert_equal("text/csv", @response.content_type)
+    assert_equal("text/csv; charset=utf-16; header=present", @response.content_type)
+    assert_equal("text/csv", @response.media_type)
+    assert_equal("utf-16", @response.charset)
+  end
+
+  test "response Content-Type with optional parameters that set before charset" do
+    @app = lambda { |env|
+      [
+        200,
+        { "Content-Type" => "text/csv; header=present; charset=utf-16" },
+        ["Hello"]
+      ]
+    }
+
+    get "/"
+    assert_response :success
+
+    assert_equal("text/csv; header=present; charset=utf-16", @response.headers["Content-Type"])
+    assert_equal("text/csv; header=present; charset=utf-16", @response.content_type)
+    assert_equal("text/csv", @response.media_type)
     assert_equal("utf-16", @response.charset)
   end
 
@@ -570,7 +589,8 @@ class ResponseIntegrationTest < ActionDispatch::IntegrationTest
     assert_response :success
 
     assert_equal('text/csv; header=present; charset="utf-16"', @response.headers["Content-Type"])
-    assert_equal("text/csv", @response.content_type)
+    assert_equal('text/csv; header=present; charset="utf-16"', @response.content_type)
+    assert_equal("text/csv", @response.media_type)
     assert_equal("utf-16", @response.charset)
   end
 end