Always use ActionDispatch::ShowExceptions middleware [#6462 state:resolved]

This will make sure the application will raise `ActionController::RoutingError` in case "X-Cascade: pass" header was set, usually when there's no route match.

railties/lib/rails/application.rb

@@ -157,7 +157,7 @@ def default_middleware_stack
         middleware.use ::Rack::Lock unless config.allow_concurrency
         middleware.use ::Rack::Runtime
         middleware.use ::Rails::Rack::Logger
-        middleware.use ::ActionDispatch::ShowExceptions, config.consider_all_requests_local if config.action_dispatch.show_exceptions
+        middleware.use ::ActionDispatch::ShowExceptions, config.consider_all_requests_local
         middleware.use ::ActionDispatch::RemoteIp, config.action_dispatch.ip_spoofing_check, config.action_dispatch.trusted_proxies
         middleware.use ::Rack::Sendfile, config.action_dispatch.x_sendfile_header
         middleware.use ::ActionDispatch::Reloader unless config.cache_classes

railties/test/application/middleware/show_exceptions_test.rb

+require 'isolation/abstract_unit'
+
+module ApplicationTests
+  class ShowExceptionsTest < Test::Unit::TestCase
+    include ActiveSupport::Testing::Isolation
+
+    def setup
+      build_app
+      boot_rails
+      FileUtils.rm_rf "#{app_path}/config/environments"
+    end
+
+    def app
+      @app ||= Rails.application
+    end
+
+    test "unspecified route when set action_dispatch.show_exceptions to false" do
+      make_basic_app do |app|
+        app.config.action_dispatch.show_exceptions = false
+      end
+
+      assert_raise(ActionController::RoutingError) do
+        get '/foo'
+      end
+    end
+
+    test "unspecified route when set action_dispatch.show_exceptions to true" do
+      make_basic_app do |app|
+        app.config.action_dispatch.show_exceptions = true
+      end
+
+      assert_nothing_raised(ActionController::RoutingError) do
+        get '/foo'
+      end
+    end
+  end
+end

railties/test/application/middleware_test.rb

@@ -78,10 +78,10 @@ def app
       assert !middleware.include?("ActionDispatch::Static")
     end
 
-    test "removes show exceptions if action_dispatch.show_exceptions is disabled" do
+    test "includes show exceptions even action_dispatch.show_exceptions is disabled" do
       add_to_config "config.action_dispatch.show_exceptions = false"
       boot!
-      assert !middleware.include?("ActionDispatch::ShowExceptions")
+      assert middleware.include?("ActionDispatch::ShowExceptions")
     end
 
     test "removes ActionDispatch::Reloader if cache_classes is true" do