Fix compatibility with Rack 3.1

.github/workflows/ci.yml

@@ -4,23 +4,32 @@ on: [push, pull_request]
 
 jobs:
   ruby:
-    name: Ruby ${{ matrix.ruby }} ${{ matrix.rubyopt }}
+    name: Ruby ${{ matrix.ruby }} / Rack ${{ matrix.rack }} ${{ matrix.rubyopt }}
     timeout-minutes: 15
     strategy:
       fail-fast: false
       matrix:
         os: ["ubuntu-latest"]
         ruby: ["ruby-head", "3.3", "3.2", "3.1", "3.0", "2.7", "2.6"]
         rubyopt: [""]
+        rack: ["~> 3.1"]
         include:
           - ruby: "3.3"
             rubyopt: "--enable-frozen-string-literal"
+            rack: "~> 3.1"
+          - ruby: "3.3"
+            rack: "~> 3.0.0"
+          - ruby: "3.3"
+            rack: "~> 2.0"
+    env:
+      RACK_VERSION: "${{ matrix.rack }}"
+      RUBYOPT: "${{ matrix.rubyopt }}"
     runs-on: ubuntu-latest
     steps:
       - name: Check out code
         uses: actions/checkout@v4
 
-      - name: Set up Ruby
+      - name: Set up Ruby ${{ matrix.ruby }}
         uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}
@@ -29,5 +38,5 @@ jobs:
       - name: Install packages
         run: sudo apt-get install -y ragel socat netcat
 
-      - name: Tests ${{ matrix.rubyopt }}
-        run: RUBYOPT="${{ matrix.rubyopt }}" bundle exec rake
+      - name: Tests Rack ${{ matrix.rack }} ${{ matrix.rubyopt }}
+        run: bundle exec rake

.gitignore

@@ -22,3 +22,4 @@ pkg/
 /LATEST
 /*_1
 test/integration/trash/
+Gemfile.lock

Gemfile

@@ -5,6 +5,9 @@ source "https://rubygems.org"
 gem 'minitest'
 gem 'rake'
 gem 'rake-compiler'
+if ENV["RACK_VERSION"]
+  gem "rack", ENV["RACK_VERSION"]
+end
 
 group :benchmark do
   gem "puma"