make sure string keys are always looked up from the class cache

actionpack/lib/action_dispatch/middleware/stack.rb

@@ -4,7 +4,7 @@ require "active_support/dependencies"
 module ActionDispatch
   class MiddlewareStack
     class Middleware
-      attr_reader :args, :block
+      attr_reader :args, :block, :name, :classcache
 
       def initialize(klass_or_name, *args, &block)
         @klass = nil
@@ -16,11 +16,12 @@ module ActionDispatch
           @name  = klass_or_name.to_s
         end
 
+        @classcache = ActiveSupport::Dependencies::Reference
         @args, @block = args, block
       end
 
       def klass
-        @klass ||= ActiveSupport::Inflector.constantize(@name)
+        @klass || classcache[@name]
       end
 
       def ==(middleware)

actionpack/test/dispatch/middleware_stack/middleware_test.rb

@@ -47,6 +47,31 @@ module ActionDispatch
         mw = Middleware.new Omg
         assert_operator mw, :==, "::#{Omg.name}"
       end
+
+      def test_middleware_loads_classnames_from_cache
+        mw = Class.new(Middleware) {
+          attr_accessor :classcache
+        }.new(Omg.name)
+
+        fake_cache    = { mw.name => Omg }
+        mw.classcache = fake_cache
+
+        assert_equal Omg, mw.klass
+
+        fake_cache[mw.name] = Middleware
+        assert_equal Middleware, mw.klass
+      end
+
+      def test_middleware_always_returns_class
+        mw = Class.new(Middleware) {
+          attr_accessor :classcache
+        }.new(Omg)
+
+        fake_cache    = { mw.name => Middleware }
+        mw.classcache = fake_cache
+
+        assert_equal Omg, mw.klass
+      end
     end
   end
 end