chore: use Rack.release rather than RACK_VERSION env

lib/rack_reverse_proxy/middleware.rb

@@ -17,7 +17,7 @@ class Middleware
     }
 
     def initialize(app = nil, &b)
-      @app = app || lambda { |_| [404, ENV['RACK_VERSION'] == '2' ? [] : {}, []] }
+      @app = app || lambda { |_| [404, rack_version_less_than_three ? [] : {}, []] }
       @rules = []
       @global_options = DEFAULT_OPTIONS
       instance_eval(&b) if block_given?
@@ -29,6 +29,10 @@ def call(env)
 
     private
 
+    def rack_version_less_than_three
+      Rack.release.split('.').first.to_i < 3
+    end
+
     def reverse_proxy_options(options)
       @global_options = @global_options.merge(options)
     end

lib/rack_reverse_proxy/roundtrip.rb

@@ -154,7 +154,7 @@ def target_response
     def response_headers
       @_response_headers ||= begin
       headers = build_response_headers
-      headers = headers.transform_keys(&:downcase) unless ENV['RACK_VERSION'] == '2'
+      headers = headers.transform_keys(&:downcase) unless rack_version_less_than_three
       headers
       end
     end
@@ -168,16 +168,9 @@ def build_response_headers
 
     def rack_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
+      rack_version_less_than_three ?  Rack::Utils::HeaderHash.new(headers) : Rack::Headers.new.merge(headers)
     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?
@@ -281,5 +274,13 @@ def non_ambiguous_match
     def ambiguous_match?
       matches.length > 1 && global_options[:matching] != :first
     end
+
+    def rack_version_less_than_three
+      Rack.release.split('.').first.to_i < 3
+    end
+
+    def set_rack_version_specific_location_header
+      rack_version_less_than_three ? 'Location' : 'location'
+    end
   end
 end

rack-reverse-proxy.gemspec

@@ -35,7 +35,7 @@ eos
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
 
-  if ENV['RACK_VERSION'] == '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/rack/reverse_proxy_spec.rb

@@ -76,7 +76,7 @@ def app
     it "produces a response header of type Headers" do
       stub_request(:get, "http://example.com/test")
       get "/test"
-      expected_class = ENV['RACK_VERSION'] == "2" ? Rack::Utils::HeaderHash : Rack::Headers
+      expected_class = rack_version_less_than_three ? Rack::Utils::HeaderHash : Rack::Headers
       expect(last_response.headers).to be_an_instance_of(expected_class)
     end
 
@@ -164,11 +164,7 @@ def app
 
       headers = last_response.headers.to_hash
       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
+      expect(headers["date"]).to rack_version_less_than_three ? be_nil : eq("Wed, 22 Jul 2015 11:27:21 GMT")
     end
 
     it "formats the headers with dashes correctly" do
@@ -180,11 +176,7 @@ def app
       get "/2test"
 
       headers = last_response.headers.to_hash
-      if ENV['RACK_VERSION'] == "2"
-        expect(headers["x-additional-info"]).to be_nil
-      else
-        expect(headers["x-additional-info"]).to eq("something")
-      end
+        expect(headers["x-additional-info"]).to eq(rack_version_less_than_three ? nil : "something")
     end
 
     it "the response header includes content-length" do
@@ -767,7 +759,7 @@ def app
     end
   end
 
-  describe "as a rack app", skip: ENV['RACK_VERSION'] == "2" do
+  describe "as a rack app", skip: rack_version_less_than_three do
     it "responds with 404 when the path is not matched" do
       get "/"
       expect(last_response).to be_not_found

spec/spec_helper.rb

@@ -103,4 +103,8 @@
 
   # User-defined configuration
   WebMock.disable_net_connect!
+
+  def rack_version_less_than_three
+    Rack.release.split('.').first.to_i < 3
+  end
 end