Experimental Rack 3 support (#2646)

* Experimental Rack 3 support

Author: twalpole

.github/workflows/build.yml

@@ -154,3 +154,29 @@ jobs:
           bundler-cache: true
       - name: Run tests inside a window manager
         run: xvfb-run sh -c "fluxbox & bundle exec rake ${{ matrix.task }}; killall fluxbox"
+
+  rack_3:
+    runs-on: ubuntu-latest
+
+    env:
+      HEADLESS: true
+      BUNDLE_GEMFILE: gemfiles/Gemfile.rack3
+
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby: ["3.2"]
+        task: ["spec_rack"]
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - name: Run smoke tests
+        run: bundle exec rake ${{ matrix.task }}
+
+

gemfiles/Gemfile.rack3

@@ -0,0 +1,8 @@
+source "https://rubygems.org"
+
+gem 'bundler', '< 3.0'
+gemspec path: '..'
+
+gem 'rack', '~>3.0.0'
+gem 'rackup'
+gem 'sinatra', github: 'dentarg/sinatra', branch: 'rack-3'

lib/capybara/registrations/servers.rb

@@ -19,6 +19,10 @@
 end
 
 Capybara.register_server :puma do |app, port, host, **options| # rubocop:disable Metrics/BlockLength
+  begin
+    require 'rackup'
+  rescue LoadError # rubocop:disable Lint/SuppressedException
+  end
   begin
     require 'rack/handler/puma'
   rescue LoadError

spec/rack_test_spec.rb

@@ -220,7 +220,7 @@ module TestSessions
       driver = described_class.new(TestApp)
 
       driver.visit('/redirect')
-      expect(driver.response.header['Location']).to be_nil
+      expect(driver.response.headers['Location']).to be_nil
       expect(driver.current_url).to match %r{/landed$}
     end
 
@@ -234,7 +234,7 @@ module TestSessions
       driver = described_class.new(TestApp, follow_redirects: false)
 
       driver.visit('/redirect')
-      expect(driver.response.header['Location']).to match %r{/redirect_again$}
+      expect(driver.response.headers['Location']).to match %r{/redirect_again$}
       expect(driver.current_url).to match %r{/redirect$}
     end
   end