Add support for testing with multiple versions of Rack

.github/workflows/ruby.yml

@@ -7,6 +7,11 @@ jobs:
     strategy:
       matrix:
         ruby: [ '2.5', '2.6', '2.7', '3.0', '3.1', '3.2', '3.3' ]
+        gemfile:
+          - "rack_2"
+          - "rack_3"
+    env:
+      BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/${{ matrix.gemfile }}.gemfile
     name: Ruby ${{ matrix.ruby }}
     steps:
     - uses: actions/checkout@v4

Gemfile

@@ -1,13 +1,8 @@
 # frozen_string_literal: true
+
 source 'https://rubygems.org'
 
 gemspec
 
-gem 'rake'
 gem 'pry'
 
-group :test do
-  gem 'rspec', '~> 3'
-  gem 'rack-test'
-  gem 'rack-session'
-end

gemfiles/rack_2.gemfile

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+gem "rack", "~> 2.2"
+
+gemspec path: "../"

gemfiles/rack_3.gemfile

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+gem "rack", "~> 3.0"
+
+gemspec path: "../"

warden.gemspec

@@ -22,4 +22,9 @@ Gem::Specification.new do |spec|
   end
   spec.require_paths = ["lib"]
   spec.add_dependency "rack", ">= 2.2.3"
+
+  spec.add_development_dependency "rake"
+  spec.add_development_dependency "rspec", "~> 3"
+  spec.add_development_dependency "rack-test"
+  spec.add_development_dependency "rack-session"
 end