Make response headers compliant with Rack 3 specification (#73)

Author: hamajyotan

lib/rack/dev-mark/middleware.rb

@@ -20,7 +20,7 @@ def call(env)
 
         read_headers = defined?(Rack::Headers) ? Rack::Headers.new(headers) : HeaderHash.new(headers)
 
-        headers['X-Rack-Dev-Mark-Env'] = CGI.escape Rack::DevMark.env
+        headers['x-rack-dev-mark-env'] = CGI.escape Rack::DevMark.env
 
         redirect = 300 <= status.to_i && status.to_i < 400
         if !redirect && !Rack::DevMark.tmp_disabled && read_headers['Content-Type'].to_s =~ %r{\btext/html\b}i
@@ -33,7 +33,7 @@ def call(env)
             end
           end
           response.close if response.respond_to?(:close)
-          headers['Content-Length'] = new_body.bytesize.to_s if read_headers['Content-Length']
+          headers['content-length'] = new_body.bytesize.to_s if read_headers['Content-Length']
           response = [new_body]
         end
 

spec/rack/dev-mark/middleware_spec.rb

@@ -25,14 +25,14 @@
     context "ASCII env string" do
       it "adds http headers" do
         _, headers, _ = subject.call({})
-        expect(headers).to include('X-Rack-Dev-Mark-Env' => 'test')
+        expect(headers).to include('x-rack-dev-mark-env' => 'test')
       end
     end
     context "Non ASCII string" do
       let(:env) { 'テスト' }
       it "adds http headers" do
         _, headers, _ = subject.call({})
-        expect(headers).to include('X-Rack-Dev-Mark-Env' => '%E3%83%86%E3%82%B9%E3%83%88')
+        expect(headers).to include('x-rack-dev-mark-env' => '%E3%83%86%E3%82%B9%E3%83%88')
       end
     end
   end