Allow custom cache-control header in AC::Live

https://github.com/rails/rails/issues/35312

2 files changed, 8 insertions, 2 deletions

diff --git a/actionpack/lib/action_controller/metal/live.rb b/actionpack/lib/action_controller/metal/live.rb
index 083b762f5a..eb43ff9c63 100644
--- a/actionpack/lib/action_controller/metal/live.rb
+++ b/actionpack/lib/action_controller/metal/live.rb
@@ -146,7 +146,7 @@ module ActionController
 
       def write(string)
         unless @response.committed?
-          @response.set_header "Cache-Control", "no-cache"
+          @response.headers["Cache-Control"] ||= "no-cache"
           @response.delete_header "Content-Length"
         end
 
diff --git a/actionpack/test/dispatch/live_response_test.rb b/actionpack/test/dispatch/live_response_test.rb
index b673fd3805..f2459112b2 100644
--- a/actionpack/test/dispatch/live_response_test.rb
+++ b/actionpack/test/dispatch/live_response_test.rb
@@ -51,11 +51,17 @@ module ActionController
         assert_equal ["omg"], @response.body_parts
       end
 
-      def test_cache_control_is_set
+      def test_cache_control_is_set_by_default
         @response.stream.write "omg"
         assert_equal "no-cache", @response.headers["Cache-Control"]
       end
 
+      def test_cache_control_is_set_manually
+        @response.set_header("Cache-Control", "public")
+        @response.stream.write "omg"
+        assert_equal "public", @response.headers["Cache-Control"]
+      end
+
       def test_content_length_is_removed
         @response.headers["Content-Length"] = "1234"
         @response.stream.write "omg"