Merge pull request #6372 from richo/bugs/middleware_stack_as_array

Add some common Array methods to the middleware stack

actionpack/lib/action_dispatch/middleware/stack.rb

@@ -75,6 +75,11 @@ def [](i)
       middlewares[i]
     end
 
+    def unshift(*args, &block)
+      middleware = self.class::Middleware.new(*args, &block)
+      middlewares.unshift(middleware)
+    end
+
     def initialize_copy(other)
       self.middlewares = other.middlewares.dup
     end

actionpack/test/dispatch/middleware_stack_test.rb

@@ -87,6 +87,11 @@ def setup
     assert_equal FooMiddleware, @stack[0].klass
   end
 
+  test "unshift adds a new middleware at the beginning of the stack" do
+    @stack.unshift :"MiddlewareStackTest::BazMiddleware"
+    assert_equal BazMiddleware, @stack.first.klass
+  end
+
   test "raise an error on invalid index" do
     assert_raise RuntimeError do
       @stack.insert("HiyaMiddleware", BazMiddleware)