test: rack 2 & 3 compat

.github/workflows/test.yml

@@ -0,0 +1,22 @@
+name: Test
+
+on: [push, pull_request]
+
+jobs:
+  test:
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby_version: ["2.7", "3.0", "3.1", "3.2", "3.3"]
+        os: ["ubuntu-latest","windows-latest","macos-latest"]
+        rack_version: ["2", "3"]
+    runs-on: ${{ matrix.os }}
+    env:
+      RACK_VERSION: ${{ matrix.rack_version }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby_version }}
+      - run: "bundle install"
+      - run: "bundle exec rake"

lib/rack_reverse_proxy/middleware.rb

@@ -17,8 +17,8 @@ class Middleware
     }
 
     def initialize(app = nil, &b)
-      @app = app || lambda { |_| [404, {}, []] }
-      @rules = []
+      @app = app || lambda { |_| [404, ENV['RACK_VERSION'] == '2' ? [] : {}, []] }
+              @rules = []
       @global_options = DEFAULT_OPTIONS
       instance_eval(&b) if block_given?
     end

lib/rack_reverse_proxy/roundtrip.rb

@@ -152,7 +152,11 @@ def target_response
     end
 
     def response_headers
-      @_response_headers ||= build_response_headers.transform_keys(&:downcase)
+      @_response_headers ||= begin
+      headers = build_response_headers
+      headers = headers.transform_keys(&:downcase) unless ENV['RACK_VERSION'] == '2'
+      headers
+      end
     end
 
     def build_response_headers
@@ -163,25 +167,30 @@ def build_response_headers
     end
 
     def rack_response_headers
-      Rack::Headers.new.merge(
-        Rack::Proxy.normalize_headers(
-          format_headers(target_response.headers)
-        )
-      )
+      headers = Rack::Proxy.normalize_headers(format_headers(target_response.headers))
+      if ENV['RACK_VERSION'] == '2'
+      Rack::Utils::HeaderHash.new(headers)
+      else
+      Rack::Headers.new.merge(headers)
+      end
+    end
+
+    def set_rack_version_specific_location_header
+      location_header = ENV['RACK_VERSION'] == '2' ? 'Location' : 'location'
     end
 
     def replace_location_header
       return unless need_replace_location?
       rewrite_uri(response_location, source_request)
-      response_headers["location"] = response_location.to_s
+      response_headers[set_rack_version_specific_location_header] = response_location.to_s
     end
 
     def response_location
-      @_response_location ||= URI(response_headers["location"] || uri)
+      @_response_location ||= URI(response_headers[set_rack_version_specific_location_header] || uri)
     end
 
     def need_replace_location?
-      response_headers["location"] && options[:replace_response_host] && response_location.host
+      response_headers[set_rack_version_specific_location_header] && options[:replace_response_host] && response_location.host
     end
 
     def setup_request

rack-reverse-proxy.gemspec

@@ -35,10 +35,15 @@ eos
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
 
-  spec.add_dependency "rack", ">= 1.0.0"
-  spec.add_dependency "rack-proxy", "~> 0.7", ">= 0.7.0"
-
-  spec.add_development_dependency "bundler", "~> 2.5"
-  spec.add_development_dependency "rake", "~> 13.2"
+  if ENV['RACK_VERSION'] == '2'
+    spec.add_dependency 'rack', ">= 1.0.0", '< 3.0'
+  else
+    spec.add_dependency 'rack', '>= 3.0', '< 4.0'
+    spec.add_dependency 'rackup', '~> 2.0'
+  end
+  spec.add_dependency "rack-proxy", "~> 0.6", ">= 0.6.1"
+
+  spec.add_development_dependency "bundler", ">= 1.7", "< 3.0"
+  spec.add_development_dependency "rake", ">= 10.3"
 end
 # rubocop:enable

spec/rack/reverse_proxy_spec.rb

@@ -76,7 +76,8 @@ def app
     it "produces a response header of type Headers" do
       stub_request(:get, "http://example.com/test")
       get "/test"
-      expect(last_response.headers).to be_an_instance_of(Rack::Headers)
+      expected_class = ENV['RACK_VERSION'] == "2" ? Rack::Utils::HeaderHash : Rack::Headers
+      expect(last_response.headers).to be_an_instance_of(expected_class)
     end
 
     it "parses the headers as a Hash with values of type String" do
@@ -163,7 +164,11 @@ def app
 
       headers = last_response.headers.to_hash
       expect(headers["Date"]).to eq("Wed, 22 Jul 2015 11:27:21 GMT")
-      expect(headers["date"]).to eq("Wed, 22 Jul 2015 11:27:21 GMT")
+      if ENV['RACK_VERSION'] == "2"
+        expect(headers["date"]).to be_nil
+      else
+        expect(headers["date"]).to eq("Wed, 22 Jul 2015 11:27:21 GMT")
+      end
     end
 
     it "formats the headers with dashes correctly" do
@@ -175,7 +180,11 @@ def app
       get "/2test"
 
       headers = last_response.headers.to_hash
-      expect(headers["x-additional-info"]).to eq("something")
+      if ENV['RACK_VERSION'] == "2"
+        expect(headers["x-additional-info"]).to be_nil
+      else
+        expect(headers["x-additional-info"]).to eq("something")
+      end
     end
 
     it "the response header includes content-length" do