Run tests against both Rack 2.x.x and 3.x.x

This ensures we’re backwardsly compatible with both versions of Rack.

Author: pezholio

.github/workflows/test.yml

@@ -9,7 +9,10 @@ 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"]
     runs-on: ${{ matrix.os }}
+    env:
+      RACK_VERSION: ${{ matrix.rack_version }}
     steps:
       - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1

pact-mock_service.gemspec

@@ -20,8 +20,12 @@ Gem::Specification.new do |gem|
   gem.require_paths = ["lib"]
   gem.license       = 'MIT'
 
-  gem.add_runtime_dependency 'rack', '>= 2.0', '< 4.0'
-  gem.add_runtime_dependency 'rackup', '~> 2.0'
+  if ENV['RACK_VERSION'] == '2'
+    gem.add_runtime_dependency 'rack', '>= 2.0', '< 3.0'
+  else
+    gem.add_runtime_dependency 'rack', '>= 3.0', '< 4.0'
+    gem.add_runtime_dependency 'rackup', '~> 2.0'
+  end
   gem.add_runtime_dependency 'rspec', '>=2.14'
   gem.add_runtime_dependency 'find_a_port', '~> 1.0.1'
   gem.add_runtime_dependency 'thor', '>= 0.19', '< 2.0'