test: upgrade to rack 3.x and add workaround to rack 3.1.x

related: pact-foundation/pact-mock_service#152

.github/workflows/test.yml

@@ -13,6 +13,9 @@ jobs:
       matrix:
         ruby_version: ["2.7", "3.0", "3.1", "3.2", "3.3"]
         os: ["ubuntu-latest","windows-latest","macos-latest"]
+        rack_version: ["2", "3"]
+    env:
+      RACK_VERSION: ${{ matrix.rack_version }}
     steps:
       - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1

Gemfile

@@ -25,5 +25,10 @@ end
 group :test do
   gem 'faraday', '~>2.0'
   gem 'faraday-retry', '~>2.0'
-  gem 'rackup', '~> 2.1'
+  if ENV['RACK_VERSION'] == '2'
+    gem 'rack', '>= 2.0', '< 3.0'
+  else
+    gem 'rack', '>= 2.0'
+    gem 'rackup', '~> 2.1'
+  end
 end

spec/support/ssl_server.rb

@@ -32,11 +32,16 @@ def webrick_opts port
   require "webrick"
   require "webrick/https"
   require "rack"
-  require "rackup/handler/webrick"
-
-  opts = webrick_opts(4444)
-
-  Rack::Handler::WEBrick.run(app, **opts) do |server|
+  begin
+    require 'rackup/handler/webrick'
+    opts = webrick_opts(4444)
+    PactWEBrick = Rackup::Handler::WEBrick
+  rescue LoadError
+      require 'rack/handler/webrick'
+      PactWEBrick = Rack::Handler::WEBrick
+      opts = webrick_opts(4444)
+  end
+  server = PactWEBrick.run(app, **opts) do |server|
     @server = server
   end
 end