Recognize should also work with route is wrapped in a constraint.

actionpack/lib/action_dispatch/routing/mapper.rb

@@ -13,6 +13,8 @@ def self.new(app, constraints, request = Rack::Request)
           end
         end
 
+        attr_reader :app
+
         def initialize(app, constraints, request)
           @app, @constraints, @request = app, constraints, request
         end

actionpack/lib/action_dispatch/routing/route_set.rb

@@ -512,6 +512,8 @@ def recognize_path(path, environment = {})
           end
 
           dispatcher = route.app
+          dispatcher = dispatcher.app while dispatcher.is_a?(Mapper::Constraints)
+
           if dispatcher.is_a?(Dispatcher) && dispatcher.controller(params, false)
             dispatcher.prepare_params!(params)
             return params

actionpack/test/dispatch/routing_test.rb

@@ -45,7 +45,10 @@ def self.matches?(request)
       match 'account/logout' => redirect("/logout"), :as => :logout_redirect
       match 'account/login', :to => redirect("/login")
 
-      match 'account/overview'
+      constraints(lambda { |req| true }) do
+        match 'account/overview'
+      end
+
       match '/account/nested/overview'
       match 'sign_in' => "sessions#new"