Merge pull request #47091 from ioquatix/rack-3-case-insensitive-headers

Use Rack's own headers classes where appropriate.

actionpack/lib/action_dispatch.rb

@@ -40,6 +40,7 @@ module ActionDispatch
 
   class IllegalStateError < StandardError
   end
+  deprecate_constant :IllegalStateError
 
   class MissingController < NameError
   end

actionpack/lib/action_dispatch/http/response.rb

@@ -32,27 +32,14 @@ module ActionDispatch # :nodoc:
   #    end
   #  end
   class Response
-    class Header < DelegateClass(Hash) # :nodoc:
-      def initialize(response, header)
-        @response = response
-        super(header)
-      end
-
-      def []=(k, v)
-        if @response.sending? || @response.sent?
-          raise ActionDispatch::IllegalStateError, "header already sent"
-        end
-
-        super
-      end
-
-      def merge(other)
-        self.class.new @response, __getobj__.merge(other)
-      end
-
-      def to_hash
-        __getobj__.dup
-      end
+    begin
+      # For `Rack::Headers` (Rack 3+):
+      require "rack/headers"
+      Header = ::Rack::Headers
+    rescue LoadError
+      # For `Rack::Utils::HeaderHash`:
+      require "rack/utils"
+      Header = ::Rack::Utils::HeaderHash
     end
 
     # The request that the response is responding to.
@@ -168,10 +155,14 @@ module ActionDispatch # :nodoc:
     # The underlying body, as a streamable object.
     attr_reader :stream
 
-    def initialize(status = 200, header = {}, body = [])
+    def initialize(status = 200, header = nil, body = [])
       super()
 
-      @header = Header.new(self, header)
+      @header = Header.new
+
+      header&.each do |key, value|
+        @header[key] = value
+      end
 
       self.body, self.status = body, status
 
@@ -461,8 +452,8 @@ module ActionDispatch # :nodoc:
       # our last chance.
       commit! unless committed?
 
-      headers.freeze
-      request.commit_cookie_jar! unless committed?
+      @header.freeze
+      @request.commit_cookie_jar! unless committed?
     end
 
     def build_buffer(response, body)

actionpack/test/controller/test_case_test.rb

@@ -1086,8 +1086,11 @@ class ResponseDefaultHeadersTest < ActionController::TestCase
   test "response contains default headers" do
     get :leave_alone
 
-    # Response headers start out with the defaults
-    assert_equal @defaults.merge("Content-Type" => "text/html"), response.headers
+    expected_headers = @defaults.merge("Content-Type" => "text/html")
+
+    expected_headers.each do |key, value|
+      assert_equal value, @response.headers[key]
+    end
   end
 
   test "response deletes a default header" do

actionpack/test/dispatch/live_response_test.rb

@@ -24,8 +24,9 @@ module ActionController
           end
         end
 
-        header = r.new.header
-        assert_kind_of(ActionController::Live::Response::Header, header)
+        headers = r.create.headers
+        assert_kind_of(ActionController::Live::Response::Header, headers)
+        assert_equal "g", headers["omg"]
       end
 
       def test_parallel
@@ -98,11 +99,10 @@ module ActionController
 
         latch.wait
         assert_predicate @response.headers, :frozen?
-        e = assert_raises(ActionDispatch::IllegalStateError) do
+        assert_raises(FrozenError) do
           @response.headers["Content-Length"] = "zomg"
         end
 
-        assert_equal "header already sent", e.message
         @response.stream.close
         t.join
       end
@@ -112,10 +112,9 @@ module ActionController
         # we can add data until it's actually written, which happens on `each`
         @response.each { |x| }
 
-        e = assert_raises(ActionDispatch::IllegalStateError) do
+        assert_raises(FrozenError) do
           @response.headers["Content-Length"] = "zomg"
         end
-        assert_equal "header already sent", e.message
       end
     end
   end

actionpack/test/dispatch/response_test.rb

@@ -423,14 +423,12 @@ class ResponseHeadersTest < ActiveSupport::TestCase
 
   test "has_header?" do
     assert @response.has_header? "Foo"
-    assert_not @response.has_header? "foo"
-    assert_not @response.has_header? nil
+    assert @response.has_header? "foo"
   end
 
   test "get_header" do
     assert_equal "1", @response.get_header("Foo")
-    assert_nil @response.get_header("foo")
-    assert_nil @response.get_header(nil)
+    assert_equal "1", @response.get_header("foo")
   end
 
   test "set_header" do
@@ -444,11 +442,6 @@ class ResponseHeadersTest < ActiveSupport::TestCase
   end
 
   test "delete_header" do
-    assert_nil @response.delete_header(nil)
-
-    assert_nil @response.delete_header("foo")
-    assert @response.has_header?("Foo")
-
     assert_equal "1", @response.delete_header("Foo")
     assert_not @response.has_header?("Foo")
   end