2 files changed, 23 insertions, 6 deletions
diff --git a/actionpack/lib/action_dispatch/testing/assertions.rb b/actionpack/lib/action_dispatch/testing/assertions.rb
index 96f08f2355..0e4a92048f 100644
--- a/actionpack/lib/action_dispatch/testing/assertions.rb
+++ b/actionpack/lib/action_dispatch/testing/assertions.rb
@@ -1,8 +1,21 @@
 module ActionDispatch
   module Assertions
-    %w(response selector tag dom routing model).each do |kind|
-      require "action_dispatch/testing/assertions/#{kind}"
-      include const_get("#{kind.camelize}Assertions")
+    autoload :DomAssertions, 'action_dispatch/testing/assertions/dom'
+    autoload :ModelAssertions, 'action_dispatch/testing/assertions/model'
+    autoload :ResponseAssertions, 'action_dispatch/testing/assertions/response'
+    autoload :RoutingAssertions, 'action_dispatch/testing/assertions/routing'
+    autoload :SelectorAssertions, 'action_dispatch/testing/assertions/selector'
+    autoload :TagAssertions, 'action_dispatch/testing/assertions/tag'
+
+    extend ActiveSupport::Concern
+
+    included do
+      include DomAssertions
+      include ModelAssertions
+      include ResponseAssertions
+      include RoutingAssertions
+      include SelectorAssertions
+      include TagAssertions
     end
   end
 end
diff --git a/actionpack/lib/action_dispatch/testing/integration.rb b/actionpack/lib/action_dispatch/testing/integration.rb
index 2c4a3a356d..40d6f97b2a 100644
--- a/actionpack/lib/action_dispatch/testing/integration.rb
+++ b/actionpack/lib/action_dispatch/testing/integration.rb
@@ -396,8 +396,12 @@ module ActionDispatch
       # Delegate unhandled messages to the current session instance.
       def method_missing(sym, *args, &block)
         reset! unless @integration_session
-        returning @integration_session.__send__(sym, *args, &block) do
-          copy_session_variables!
+        if @integration_session.respond_to?(sym)
+          returning @integration_session.__send__(sym, *args, &block) do
+            copy_session_variables!
+          end
+        else
+          super
         end
       end
     end
@@ -486,7 +490,7 @@ module ActionDispatch
     def self.app
       # DEPRECATE Rails application fallback
       # This should be set by the initializer
-      @@app || (defined?(Rails.application) && Rails.application.new) || nil
+      @@app || (defined?(Rails.application) && Rails.application) || nil
     end
 
     def self.app=(app)