Add spec adapter with ActiveSupport for comparison testing

Gemfile

@@ -34,4 +34,5 @@ end
 group :spec do
   # Minimum required: 3d1b492 (run `bundle update liquid-spec` to get newer)
   gem 'liquid-spec', github: 'Shopify/liquid-spec', ref: '3d1b492dce27cd78b4d5a46ca8cf260ae1349f29'
+  gem 'activesupport'
 end

spec/ruby_liquid_with_active_support.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+# Liquid Spec Adapter for Shopify/liquid with ActiveSupport loaded
+#
+# Run with: bundle exec liquid-spec run spec/ruby_liquid_with_active_support.rb
+
+$LOAD_PATH.unshift(File.expand_path('../lib', __dir__))
+require 'active_support/all'
+require 'liquid'
+
+LiquidSpec.configure do |config|
+  # Run core Liquid specs
+  config.features = [:core]
+end
+
+# Compile a template string into a Liquid::Template
+LiquidSpec.compile do |source, options|
+  Liquid::Template.parse(source, **options)
+end
+
+# Render a compiled template with the given context
+# @param template [Liquid::Template] compiled template
+# @param assigns [Hash] environment variables
+# @param options [Hash] :registers, :strict_errors, :exception_renderer
+LiquidSpec.render do |template, assigns, options|
+  registers = Liquid::Registers.new(options[:registers] || {})
+
+  context = Liquid::Context.build(
+    static_environments: assigns,
+    registers: registers,
+    rethrow_errors: options[:strict_errors],
+  )
+
+  context.exception_renderer = options[:exception_renderer] if options[:exception_renderer]
+
+  template.render(context)
+end