Fix header tests.

Author: samuel-williams-shopify

lib/protocol/rack/adapter/rack2.rb

@@ -165,7 +165,11 @@ def self.make_response(env, response)
 					end
 
 					headers.transform_values! do |value|
-						value.is_a?(Array) ? value.join("\n") : value
+						if value.is_a?(Array)
+							value.join("\n")
+						else
+							value
+						end
 					end
 
 					[response.status, headers, body]

lib/protocol/rack/adapter/rack3.rb

@@ -130,14 +130,6 @@ def self.make_response(env, response)
 						# Force streaming response:
 						body = body.method(:call)
 					end
-
-					headers.transform_values! do |value|
-						if value.is_a?(Array) and value.size == 1
-							value.first
-						else
-							value
-						end
-					end
 
 					[response.status, headers, body]
 				end

test/protocol/rack/adapter.rb

@@ -55,20 +55,22 @@
 			response = Protocol::HTTP::Response[200, headers: {"x-custom" => "123"}, body: ["Hello World!"]]
 			status, headers, body = subject.make_response(env, response)
 
-			expect(headers["x-custom"]).to be == "123"
+			x_custom = headers["x-custom"]
+
+			expect(x_custom).to (be == "123").or(be == ["123"])
 		end
 
 		it "can wrap multi-value headers" do
-			response = Protocol::HTTP::Response[200, headers: {"set-cookie" => ["a=b", "x=y"]}, body: ["Hello World!"]]
+			response = Protocol::HTTP::Response[200, headers: [["x-custom", "a=b"], ["x-custom", "x=y"]], body: ["Hello World!"]]
 
 			status, headers, body = subject.make_response(env, response)
 
-			set_cookie = headers["set-cookie"]
+			x_custom = headers["x-custom"]
 
 			if subject::VERSION < "3"
-				expect(set_cookie).to be == "a=b\nx=y"
+				expect(x_custom).to be == "a=b\nx=y"
 			else
-				expect(set_cookie).to be == ["a=b", "x=y"]
+				expect(x_custom).to be == ["a=b", "x=y"]
 			end
 		end
 	end

test/protocol/rack/adapter/rack31.rb

@@ -4,7 +4,6 @@
 # Copyright, 2025, by Samuel Williams.
 
 require "sus/fixtures/console"
-require "rack/mock_request"
 
 require "protocol/http/request"
 require "protocol/rack/adapter/rack31"