Use Protocol::Rack::Adapter.parse_file for compatibility with older Rack versions. (#232)

* Restore workflow for multiple rack versions.

Author: ioquatix

.github/workflows/test.yaml

@@ -10,10 +10,13 @@ env:
 
 jobs:
   test:
-    name: ${{matrix.ruby}} on ${{matrix.os}}
+    name: ${{matrix.ruby}} on ${{matrix.os}} ${{matrix.gemfile}}
     runs-on: ${{matrix.os}}-latest
     continue-on-error: ${{matrix.experimental}}
 
+    env:
+      BUNDLER_GEMFILE: ${{matrix.gemfile}}
+    
     strategy:
       matrix:
         os:
@@ -26,6 +29,12 @@ jobs:
           - "3.2"
           - "3.3"
 
+        gemfile:
+          - gems/rack-v1.rb
+          - gems/rack-v2.rb
+          - gems/rack-v3.rb
+          - gems/rack-head.rb
+        
         experimental: [false]
 
         include:

falcon.gemspec

@@ -35,6 +35,6 @@ Gem::Specification.new do |spec|
 	spec.add_dependency "localhost", "~> 1.1"
 	spec.add_dependency "openssl", "~> 3.0"
 	spec.add_dependency "process-metrics", "~> 0.2.0"
-	spec.add_dependency "protocol-rack", "~> 0.1"
+	spec.add_dependency "protocol-rack", "~> 0.5"
 	spec.add_dependency "samovar", "~> 2.3"
 end

lib/falcon/environment/rackup.rb

@@ -15,7 +15,7 @@ def rackup_path
 			end
 
 			def rack_app
-				::Rack::Builder.parse_file(rackup_path)
+				::Protocol::Rack::Adapter.parse_file(rackup_path)
 			end
 
 			def middleware