diff --git a/Gemfile b/Gemfile
index 92ca601..e89e6d0 100644
--- a/Gemfile
+++ b/Gemfile
@@ -14,6 +14,7 @@ end
 
 group :test do
   gem "rspec-rails"
+  gem "super_engine", path: "spec/dummies/with-engine/dummy/engines/super_engine", require: false
 end
 
 group :tools do
diff --git a/dry-rails.gemspec b/dry-rails.gemspec
index 08901ed..0070315 100644
--- a/dry-rails.gemspec
+++ b/dry-rails.gemspec
@@ -36,4 +36,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "bundler"
   spec.add_development_dependency "rake"
   spec.add_development_dependency "rspec"
+
+  # our super engine used in specs
+  spec.add_development_dependency "super_engine"
 end
diff --git a/lib/dry/rails.rb b/lib/dry/rails.rb
index b5ea529..0e8b7e9 100644
--- a/lib/dry/rails.rb
+++ b/lib/dry/rails.rb
@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 require "dry/rails/railtie"
+require "dry/rails/engine"
+require "dry/rails/finalizer"
 require "dry/rails/container"
 require "dry/rails/components"
 
@@ -20,14 +22,24 @@ module Dry
   #
   # @api public
   module Rails
+    extend Configurable
+    # Set to true to turn off dry-system for main application
+    # Meant to be used in setup where dry-system is only used within Rails::Engine(s)
+    #
+    # @api public
+    setting :main_app_disabled, default: false
+
+    # This is being injected by main app Railtie
+    # @api private
+    setting :main_app_name
+
     # Set container block that will be evaluated in the context of the container
     #
     # @return [self]
     #
     # @api public
     def self.container(&block)
-      _container_blocks << block
-      self
+      Engine.container(config.main_app_name, &block)
     end
 
     # Create a new container class
@@ -40,19 +52,12 @@ def self.container(&block)
     #
     # @api private
     def self.create_container(options = {})
-      Class.new(Container) { config.update(options) }
+      Engine.create_container(options)
     end
 
     # @api private
     def self.evaluate_initializer(container)
-      _container_blocks.each do |block|
-        container.class_eval(&block)
-      end
-    end
-
-    # @api private
-    def self._container_blocks
-      @_container_blocks ||= []
+      Engine.evaluate_initializer(config.main_app_name, container)
     end
   end
 end
diff --git a/lib/dry/rails/boot/safe_params.rb b/lib/dry/rails/boot/safe_params.rb
index f0c014d..4fd21c2 100644
--- a/lib/dry/rails/boot/safe_params.rb
+++ b/lib/dry/rails/boot/safe_params.rb
@@ -6,7 +6,7 @@
   end
 
   start do
-    ApplicationController.include(Dry::Rails::Features::SafeParams)
+    ActionController::Base.include(Dry::Rails::Features::SafeParams)
 
     if defined?(ActionController::API)
       ActionController::API.include(Dry::Rails::Features::SafeParams)
diff --git a/lib/dry/rails/engine.rb b/lib/dry/rails/engine.rb
new file mode 100644
index 0000000..3e5daac
--- /dev/null
+++ b/lib/dry/rails/engine.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module Dry
+  module Rails
+    module Engine
+      # Set container block that will be evaluated in the context of the container
+      #
+      # @param name [Symbol]
+      # @return [self]
+      #
+      # @api public
+      def self.container(name, &block)
+        _container_blocks[name] << block
+        self
+      end
+
+      # Create a new container class
+      #
+      # This is used during booting and reloading
+      #
+      # @param name [Symbol]
+      # @param options [Hash] Container configuration settings
+      #
+      # @return [Class]
+      #
+      # @api private
+      def self.create_container(options = {})
+        Class.new(Container) { config.update(options) }
+      end
+
+      # @api private
+      def self.evaluate_initializer(name, container)
+        _container_blocks[name].each do |block|
+          container.class_eval(&block)
+        end
+      end
+
+      # @api private
+      def self._container_blocks
+        @_container_blocks ||= Hash.new { |h, k| h[k] = [] }
+      end
+    end
+  end
+end
diff --git a/lib/dry/rails/finalizer.rb b/lib/dry/rails/finalizer.rb
new file mode 100644
index 0000000..1236cdc
--- /dev/null
+++ b/lib/dry/rails/finalizer.rb
@@ -0,0 +1,172 @@
+# frozen_string_literal: true
+
+module Dry
+  module Rails
+    class Finalizer
+      def self.app_namespace_to_name(app_namespace)
+        app_namespace.name.underscore.to_sym
+      end
+
+      # rubocop:disable Metrics/ParameterLists
+      def initialize(
+        railtie:,
+        app_namespace:,
+        root_path:,
+        name: Dry::Rails.config.main_app_name,
+        container_const_name: Dry::Rails::Container.container_constant,
+        default_inflector: ActiveSupport::Inflector
+      )
+        @railtie = railtie
+        @app_namespace = app_namespace
+        @root_path = root_path
+        @name = name
+        @container_const_name = container_const_name
+        @default_inflector = default_inflector
+      end
+      # rubocop:enable Metrics/ParameterLists
+
+      attr_reader :railtie,
+                  :root_path,
+                  :container_const_name
+
+      # Infer the default application namespace
+      #
+      # TODO: we had to rename namespace=>app_namespace because
+      #       Rake::DSL's Kernel#namespace *sometimes* breaks things.
+      #       Currently we are missing specs verifying that rake tasks work
+      #       correctly and those must be added!
+      #
+      # @return [Module]
+      #
+      # @api public
+      attr_reader :app_namespace
+
+      # Code-reloading-aware finalization process
+      #
+      # This sets up `Container` and `Deps` constants, reloads them if this is in reloading mode,
+      # and registers default components like the railtie itself or the inflector
+      #
+      # @api public
+      #
+      # rubocop:disable Metrics/AbcSize
+      def finalize!
+        stop_features if reloading?
+
+        container = Dry::Rails::Engine.create_container(
+          root: root_path,
+          inflector: default_inflector,
+          system_dir: root_path.join("config/system"),
+          bootable_dirs: [root_path.join("config/system/boot")]
+        )
+
+        # Enable :env plugin by default because it is a very common requirement
+        container.use :env, inferrer: -> { ::Rails.env }
+
+        container.register(:railtie, railtie)
+        container.register(:inflector, default_inflector)
+
+        # Remove previously defined constants, if any, so we don't end up with
+        # unsused constants in app's namespace when a name change happens.
+        remove_constant(container.auto_inject_constant)
+        remove_constant(container.container_constant)
+
+        Dry::Rails::Engine.evaluate_initializer(name, container)
+
+        @container_const_name = container.container_constant
+
+        set_or_reload(container.container_constant, container)
+        set_or_reload(container.auto_inject_constant, container.injector)
+
+        container.features.each do |feature|
+          container.boot(feature, from: :rails)
+        end
+
+        container.refresh_boot_files if reloading?
+
+        container.finalize!(freeze: !::Rails.env.test?)
+      end
+      # rubocop:enable Metrics/AbcSize
+
+      # Stops all configured features (bootable components)
+      #
+      # This is *crucial* when reloading code in development mode. Every bootable component
+      # should be able to clear the runtime from any constants that it created in its `stop`
+      # lifecycle step
+      #
+      # @api public
+      def stop_features
+        container.features.each do |feature|
+          container.stop(feature) if container.booted?(feature)
+        end
+      end
+
+      # Exposes the container constant
+      #
+      # @return [Dry::Rails::Container]
+      #
+      # @api public
+      def container
+        app_namespace.const_get(container_const_name, false)
+      end
+
+      # Return true if we're in code-reloading mode
+      #
+      # @api private
+      def reloading?
+        app_namespace.const_defined?(container_const_name, false)
+      end
+
+      # Return the default system name
+      #
+      # In the dry-system world containers are explicitly named using symbols, so that you can
+      # refer to them easily when ie importing one container into another
+      #
+      # @return [Symbol]
+      #
+      # @api private
+      attr_reader :name
+
+      # Sets or reloads a constant within the application namespace
+      #
+      # @api private
+      attr_reader :default_inflector
+
+      # @api private
+      def set_or_reload(const_name, const)
+        remove_constant(const_name)
+        app_namespace.const_set(const_name, const)
+      end
+
+      # @api private
+      def remove_constant(const_name)
+        if app_namespace.const_defined?(const_name, false)
+          app_namespace.__send__(:remove_const, const_name)
+        end
+      end
+    end
+
+    module Engine
+      class Finalizer
+        # rubocop:disable Metrics/ParameterLists
+        def self.new(
+          railtie:,
+          app_namespace:,
+          root_path:,
+          name: nil,
+          container_const_name: Dry::Rails::Container.container_constant,
+          default_inflector: ActiveSupport::Inflector
+        )
+          Dry::Rails::Finalizer.new(
+            railtie: railtie,
+            app_namespace: app_namespace,
+            root_path: root_path,
+            name: name || ::Dry::Rails::Finalizer.app_namespace_to_name(app_namespace),
+            container_const_name: container_const_name,
+            default_inflector: default_inflector
+          )
+        end
+        # rubocop:enable Metrics/ParameterLists
+      end
+    end
+  end
+end
diff --git a/lib/dry/rails/railtie.rb b/lib/dry/rails/railtie.rb
index 4063b93..9b3f808 100644
--- a/lib/dry/rails/railtie.rb
+++ b/lib/dry/rails/railtie.rb
@@ -8,12 +8,31 @@ module Rails
     #
     # @api public
     class Railtie < ::Rails::Railtie
-      attr_reader :container_const_name
-
       # This is needed because `finalize!` can reload code and this hook is called every-time
       # in development env upon a request (in production it's called just once during booting)
       config.to_prepare do
-        Railtie.finalize!
+        Railtie.finalize! unless Dry::Rails.config.main_app_disabled
+      end
+
+      initializer "dry-rails.main-app-container" do
+        Dry::Rails.config.main_app_name = Dry::Rails::Finalizer.app_namespace_to_name(app_namespace)
+      end
+
+      # Infer the default application namespace
+      #
+      # TODO: we had to rename namespace=>app_namespace because
+      #       Rake::DSL's Kernel#namespace *sometimes* breaks things.
+      #       Currently we are missing specs verifying that rake tasks work
+      #       correctly and those must be added!
+      #
+      # @return [Module]
+      #
+      # @api public
+      def app_namespace
+        @app_namespace ||= begin
+          top_level_namespace = ::Rails.application.class.to_s.split("::").first
+          Object.const_get(top_level_namespace)
+        end
       end
 
       # Code-reloading-aware finalization process
@@ -22,49 +41,7 @@ class Railtie < ::Rails::Railtie
       # and registers default components like the railtie itself or the inflector
       #
       # @api public
-      #
-      # rubocop:disable Metrics/AbcSize
-      def finalize!
-        @container_const_name ||= Dry::Rails::Container.container_constant
-
-        stop_features if reloading?
-
-        root_path = ::Rails.root
-
-        container = Dry::Rails.create_container(
-          root: root_path,
-          inflector: default_inflector,
-          system_dir: root_path.join("config/system"),
-          bootable_dirs: [root_path.join("config/system/boot")]
-        )
-
-        # Enable :env plugin by default because it is a very common requirement
-        container.use :env, inferrer: -> { ::Rails.env }
-
-        container.register(:railtie, self)
-        container.register(:inflector, default_inflector)
-
-        # Remove previously defined constants, if any, so we don't end up with
-        # unsused constants in app's namespace when a name change happens.
-        remove_constant(container.auto_inject_constant)
-        remove_constant(container.container_constant)
-
-        Dry::Rails.evaluate_initializer(container)
-
-        @container_const_name = container.container_constant
-
-        set_or_reload(container.container_constant, container)
-        set_or_reload(container.auto_inject_constant, container.injector)
-
-        container.features.each do |feature|
-          container.boot(feature, from: :rails)
-        end
-
-        container.refresh_boot_files if reloading?
-
-        container.finalize!(freeze: !::Rails.env.test?)
-      end
-      # rubocop:enable Metrics/AbcSize
+      delegate :finalize!, to: :finalizer
       alias_method :reload, :finalize!
 
       # Stops all configured features (bootable components)
@@ -74,75 +51,29 @@ def finalize!
       # lifecycle step
       #
       # @api public
-      def stop_features
-        container.features.each do |feature|
-          container.stop(feature) if container.booted?(feature)
-        end
-      end
+      delegate :stop_features, to: :finalizer
 
       # Exposes the container constant
       #
       # @return [Dry::Rails::Container]
       #
       # @api public
-      def container
-        app_namespace.const_get(container_const_name, false)
-      end
+      delegate :container, to: :finalizer
 
-      # Return true if we're in code-reloading mode
-      #
       # @api private
-      def reloading?
-        app_namespace.const_defined?(container_const_name, false)
-      end
+      delegate :set_or_reload, to: :finalizer
 
-      # Return the default system name
-      #
-      # In the dry-system world containers are explicitly named using symbols, so that you can
-      # refer to them easily when ie importing one container into another
-      #
-      # @return [Symbol]
-      #
       # @api private
-      def name
-        app_namespace.name.underscore.to_sym
-      end
+      delegate :remove_constant, to: :finalizer
 
-      # Infer the default application namespace
-      #
-      # TODO: we had to rename namespace=>app_namespace because
-      #       Rake::DSL's Kernel#namespace *sometimes* breaks things.
-      #       Currently we are missing specs verifying that rake tasks work
-      #       correctly and those must be added!
-      #
-      # @return [Module]
-      #
-      # @api public
-      def app_namespace
-        @app_namespace ||= begin
-          top_level_namespace = ::Rails.application.class.to_s.split("::").first
-          Object.const_get(top_level_namespace)
-        end
-      end
+      private
 
-      # Sets or reloads a constant within the application namespace
-      #
-      # @api private
-      def default_inflector
-        ActiveSupport::Inflector
-      end
-
-      # @api private
-      def set_or_reload(const_name, const)
-        remove_constant(const_name)
-        app_namespace.const_set(const_name, const)
-      end
-
-      # @api private
-      def remove_constant(const_name)
-        if app_namespace.const_defined?(const_name, false)
-          app_namespace.__send__(:remove_const, const_name)
-        end
+      def finalizer
+        @finalizer ||= Finalizer.new(
+          railtie: self,
+          app_namespace: app_namespace,
+          root_path: ::Rails.root
+        )
       end
     end
   end
diff --git a/spec/dummy-5.x/dummy/.rspec b/spec/dummies/with-engine/dummy-5.x/dummy/.rspec
similarity index 100%
rename from spec/dummy-5.x/dummy/.rspec
rename to spec/dummies/with-engine/dummy-5.x/dummy/.rspec
diff --git a/spec/dummies/with-engine/dummy-5.x/dummy/Gemfile b/spec/dummies/with-engine/dummy-5.x/dummy/Gemfile
new file mode 100644
index 0000000..609014c
--- /dev/null
+++ b/spec/dummies/with-engine/dummy-5.x/dummy/Gemfile
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+gem "actionpack"
+gem "dry-rails", path: "../../../.."
+gem "listen"
+gem "railties"
+gem "super_engine", path: "engines/super_engine"
diff --git a/spec/dummy-5.x/dummy/app b/spec/dummies/with-engine/dummy-5.x/dummy/app
similarity index 100%
rename from spec/dummy-5.x/dummy/app
rename to spec/dummies/with-engine/dummy-5.x/dummy/app
diff --git a/spec/dummy-5.x/dummy/config/application.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/application.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/application.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/application.rb
diff --git a/spec/dummy-5.x/dummy/config/boot.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/boot.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/boot.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/boot.rb
diff --git a/spec/dummies/with-engine/dummy-5.x/dummy/config/environment.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/environment.rb
new file mode 100644
index 0000000..18213e5
--- /dev/null
+++ b/spec/dummies/with-engine/dummy-5.x/dummy/config/environment.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+# Load the Rails application.
+require_relative "application"
+require "super_engine"
+
+# Initialize the Rails application.
+Rails.application.initialize!
diff --git a/spec/dummy-5.x/dummy/config/environments/development.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/environments/development.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/environments/development.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/environments/development.rb
diff --git a/spec/dummy-5.x/dummy/config/environments/production.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/environments/production.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/environments/production.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/environments/production.rb
diff --git a/spec/dummy-5.x/dummy/config/environments/test.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/environments/test.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/environments/test.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/environments/test.rb
diff --git a/spec/dummy-5.x/dummy/config/initializers/application_controller_renderer.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/application_controller_renderer.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/initializers/application_controller_renderer.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/application_controller_renderer.rb
diff --git a/spec/dummy-5.x/dummy/config/initializers/backtrace_silencers.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/backtrace_silencers.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/initializers/backtrace_silencers.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/backtrace_silencers.rb
diff --git a/spec/dummy-5.x/dummy/config/initializers/cookies_serializer.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/cookies_serializer.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/initializers/cookies_serializer.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/cookies_serializer.rb
diff --git a/spec/dummy-5.x/dummy/config/initializers/filter_parameter_logging.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/filter_parameter_logging.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/initializers/filter_parameter_logging.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/filter_parameter_logging.rb
diff --git a/spec/dummy-5.x/dummy/config/initializers/inflections.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/inflections.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/initializers/inflections.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/inflections.rb
diff --git a/spec/dummy-5.x/dummy/config/initializers/mime_types.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/mime_types.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/initializers/mime_types.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/mime_types.rb
diff --git a/spec/dummy-5.x/dummy/config/initializers/new_framework_defaults.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/new_framework_defaults.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/initializers/new_framework_defaults.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/new_framework_defaults.rb
diff --git a/spec/dummy-5.x/dummy/config/initializers/session_store.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/session_store.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/initializers/session_store.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/session_store.rb
diff --git a/spec/dummy-5.x/dummy/config/initializers/system.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/system.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/initializers/system.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/system.rb
diff --git a/spec/dummy-5.x/dummy/config/initializers/wrap_parameters.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/wrap_parameters.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/initializers/wrap_parameters.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/initializers/wrap_parameters.rb
diff --git a/spec/dummy-5.x/dummy/config/locales b/spec/dummies/with-engine/dummy-5.x/dummy/config/locales
similarity index 100%
rename from spec/dummy-5.x/dummy/config/locales
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/locales
diff --git a/spec/dummy-5.x/dummy/config/routes.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/routes.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/routes.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/routes.rb
diff --git a/spec/dummy-5.x/dummy/config/secrets.yml b/spec/dummies/with-engine/dummy-5.x/dummy/config/secrets.yml
similarity index 100%
rename from spec/dummy-5.x/dummy/config/secrets.yml
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/secrets.yml
diff --git a/spec/dummy-5.x/dummy/config/spring.rb b/spec/dummies/with-engine/dummy-5.x/dummy/config/spring.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/spring.rb
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/spring.rb
diff --git a/spec/dummy-5.x/dummy/config/system b/spec/dummies/with-engine/dummy-5.x/dummy/config/system
similarity index 100%
rename from spec/dummy-5.x/dummy/config/system
rename to spec/dummies/with-engine/dummy-5.x/dummy/config/system
diff --git a/spec/dummies/with-engine/dummy-5.x/dummy/engines b/spec/dummies/with-engine/dummy-5.x/dummy/engines
new file mode 120000
index 0000000..cf9958b
--- /dev/null
+++ b/spec/dummies/with-engine/dummy-5.x/dummy/engines
@@ -0,0 +1 @@
+../../dummy/engines
\ No newline at end of file
diff --git a/spec/dummy-5.x/dummy/lib b/spec/dummies/with-engine/dummy-5.x/dummy/lib
similarity index 100%
rename from spec/dummy-5.x/dummy/lib
rename to spec/dummies/with-engine/dummy-5.x/dummy/lib
diff --git a/spec/dummy-5.x/dummy/log/.keep b/spec/dummies/with-engine/dummy-5.x/dummy/log/.keep
similarity index 100%
rename from spec/dummy-5.x/dummy/log/.keep
rename to spec/dummies/with-engine/dummy-5.x/dummy/log/.keep
diff --git a/spec/dummies/with-engine/dummy-6.x/dummy/Gemfile b/spec/dummies/with-engine/dummy-6.x/dummy/Gemfile
new file mode 100644
index 0000000..dff8c3a
--- /dev/null
+++ b/spec/dummies/with-engine/dummy-6.x/dummy/Gemfile
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+git_source(:github) { |repo| "https://github.com/#{repo}.git" }
+
+ruby "2.6.5"
+
+gem "dry-rails", path: "../../../../.."
+gem "super_engine", path: "engines/super_engine"
+
+# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
+gem "rails", "~> 6.0.2", ">= 6.0.2.1"
+# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
+gem "jbuilder", "~> 2.7"
+# Use Active Model has_secure_password
+# gem 'bcrypt', '~> 3.1.7'
+
+group :development, :test do
+  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
+  gem "byebug", platforms: %i[mri mingw x64_mingw]
+end
+
+group :development do
+  # Access an interactive console on exception pages or by calling 'console' anywhere in the code.
+  gem "listen", ">= 3.0.5", "< 3.2"
+  gem "web-console", ">= 3.3.0"
+  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
+  gem "spring"
+  gem "spring-watcher-listen", "~> 2.0.0"
+end
+
+# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
+gem "tzinfo-data", platforms: %i[mingw mswin x64_mingw jruby]
diff --git a/spec/dummy-6.x/dummy/app b/spec/dummies/with-engine/dummy-6.x/dummy/app
similarity index 100%
rename from spec/dummy-6.x/dummy/app
rename to spec/dummies/with-engine/dummy-6.x/dummy/app
diff --git a/spec/dummy-6.x/dummy/config/application.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/application.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/application.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/application.rb
diff --git a/spec/dummy-6.x/dummy/config/boot.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/boot.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/boot.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/boot.rb
diff --git a/spec/dummy-6.x/dummy/config/credentials.yml.enc b/spec/dummies/with-engine/dummy-6.x/dummy/config/credentials.yml.enc
similarity index 100%
rename from spec/dummy-6.x/dummy/config/credentials.yml.enc
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/credentials.yml.enc
diff --git a/spec/dummies/with-engine/dummy-6.x/dummy/config/environment.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/environment.rb
new file mode 100644
index 0000000..18213e5
--- /dev/null
+++ b/spec/dummies/with-engine/dummy-6.x/dummy/config/environment.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+# Load the Rails application.
+require_relative "application"
+require "super_engine"
+
+# Initialize the Rails application.
+Rails.application.initialize!
diff --git a/spec/dummy-6.x/dummy/config/environments/development.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/environments/development.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/environments/development.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/environments/development.rb
diff --git a/spec/dummy-6.x/dummy/config/environments/production.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/environments/production.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/environments/production.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/environments/production.rb
diff --git a/spec/dummy-6.x/dummy/config/environments/test.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/environments/test.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/environments/test.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/environments/test.rb
diff --git a/spec/dummy-6.x/dummy/config/initializers/application_controller_renderer.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/application_controller_renderer.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/initializers/application_controller_renderer.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/application_controller_renderer.rb
diff --git a/spec/dummy-6.x/dummy/config/initializers/backtrace_silencers.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/backtrace_silencers.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/initializers/backtrace_silencers.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/backtrace_silencers.rb
diff --git a/spec/dummy-6.x/dummy/config/initializers/content_security_policy.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/content_security_policy.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/initializers/content_security_policy.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/content_security_policy.rb
diff --git a/spec/dummy-6.x/dummy/config/initializers/cookies_serializer.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/cookies_serializer.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/initializers/cookies_serializer.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/cookies_serializer.rb
diff --git a/spec/dummy-6.x/dummy/config/initializers/filter_parameter_logging.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/filter_parameter_logging.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/initializers/filter_parameter_logging.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/filter_parameter_logging.rb
diff --git a/spec/dummy-6.x/dummy/config/initializers/inflections.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/inflections.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/initializers/inflections.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/inflections.rb
diff --git a/spec/dummy-6.x/dummy/config/initializers/mime_types.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/mime_types.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/initializers/mime_types.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/mime_types.rb
diff --git a/spec/dummy-6.x/dummy/config/initializers/system.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/system.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/initializers/system.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/system.rb
diff --git a/spec/dummy-6.x/dummy/config/initializers/wrap_parameters.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/wrap_parameters.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/initializers/wrap_parameters.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/initializers/wrap_parameters.rb
diff --git a/spec/dummy-6.x/dummy/config/locales b/spec/dummies/with-engine/dummy-6.x/dummy/config/locales
similarity index 100%
rename from spec/dummy-6.x/dummy/config/locales
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/locales
diff --git a/spec/dummy-6.x/dummy/config/master.key b/spec/dummies/with-engine/dummy-6.x/dummy/config/master.key
similarity index 100%
rename from spec/dummy-6.x/dummy/config/master.key
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/master.key
diff --git a/spec/dummy-6.x/dummy/config/routes.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/routes.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/routes.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/routes.rb
diff --git a/spec/dummy-6.x/dummy/config/spring.rb b/spec/dummies/with-engine/dummy-6.x/dummy/config/spring.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/spring.rb
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/spring.rb
diff --git a/spec/dummy-6.x/dummy/config/system b/spec/dummies/with-engine/dummy-6.x/dummy/config/system
similarity index 100%
rename from spec/dummy-6.x/dummy/config/system
rename to spec/dummies/with-engine/dummy-6.x/dummy/config/system
diff --git a/spec/dummies/with-engine/dummy-6.x/dummy/engines b/spec/dummies/with-engine/dummy-6.x/dummy/engines
new file mode 120000
index 0000000..cf9958b
--- /dev/null
+++ b/spec/dummies/with-engine/dummy-6.x/dummy/engines
@@ -0,0 +1 @@
+../../dummy/engines
\ No newline at end of file
diff --git a/spec/dummy-6.x/dummy/lib b/spec/dummies/with-engine/dummy-6.x/dummy/lib
similarity index 100%
rename from spec/dummy-6.x/dummy/lib
rename to spec/dummies/with-engine/dummy-6.x/dummy/lib
diff --git a/spec/dummy-6.x/dummy/log/.keep b/spec/dummies/with-engine/dummy-6.x/dummy/log/.keep
similarity index 100%
rename from spec/dummy-6.x/dummy/log/.keep
rename to spec/dummies/with-engine/dummy-6.x/dummy/log/.keep
diff --git a/spec/dummy/app/controllers/api_safe_params_callbacks_controller.rb b/spec/dummies/with-engine/dummy/app/controllers/api_safe_params_callbacks_controller.rb
similarity index 100%
rename from spec/dummy/app/controllers/api_safe_params_callbacks_controller.rb
rename to spec/dummies/with-engine/dummy/app/controllers/api_safe_params_callbacks_controller.rb
diff --git a/spec/dummy/app/controllers/api_users_controller.rb b/spec/dummies/with-engine/dummy/app/controllers/api_users_controller.rb
similarity index 100%
rename from spec/dummy/app/controllers/api_users_controller.rb
rename to spec/dummies/with-engine/dummy/app/controllers/api_users_controller.rb
diff --git a/spec/dummy/app/controllers/application_controller.rb b/spec/dummies/with-engine/dummy/app/controllers/application_controller.rb
similarity index 100%
rename from spec/dummy/app/controllers/application_controller.rb
rename to spec/dummies/with-engine/dummy/app/controllers/application_controller.rb
diff --git a/spec/dummy/app/controllers/safe_params_callbacks_controller.rb b/spec/dummies/with-engine/dummy/app/controllers/safe_params_callbacks_controller.rb
similarity index 100%
rename from spec/dummy/app/controllers/safe_params_callbacks_controller.rb
rename to spec/dummies/with-engine/dummy/app/controllers/safe_params_callbacks_controller.rb
diff --git a/spec/dummy/app/controllers/users_controller.rb b/spec/dummies/with-engine/dummy/app/controllers/users_controller.rb
similarity index 100%
rename from spec/dummy/app/controllers/users_controller.rb
rename to spec/dummies/with-engine/dummy/app/controllers/users_controller.rb
diff --git a/spec/dummy/app/forms/create_user_form.rb b/spec/dummies/with-engine/dummy/app/forms/create_user_form.rb
similarity index 100%
rename from spec/dummy/app/forms/create_user_form.rb
rename to spec/dummies/with-engine/dummy/app/forms/create_user_form.rb
diff --git a/spec/dummy/app/models/container.rb b/spec/dummies/with-engine/dummy/app/models/container.rb
similarity index 100%
rename from spec/dummy/app/models/container.rb
rename to spec/dummies/with-engine/dummy/app/models/container.rb
diff --git a/spec/dummy/app/models/user_repo.rb b/spec/dummies/with-engine/dummy/app/models/user_repo.rb
similarity index 100%
rename from spec/dummy/app/models/user_repo.rb
rename to spec/dummies/with-engine/dummy/app/models/user_repo.rb
diff --git a/spec/dummy/app/operations/create_user.rb b/spec/dummies/with-engine/dummy/app/operations/create_user.rb
similarity index 100%
rename from spec/dummy/app/operations/create_user.rb
rename to spec/dummies/with-engine/dummy/app/operations/create_user.rb
diff --git a/spec/dummy/app/services/github.rb b/spec/dummies/with-engine/dummy/app/services/github.rb
similarity index 100%
rename from spec/dummy/app/services/github.rb
rename to spec/dummies/with-engine/dummy/app/services/github.rb
diff --git a/spec/dummy/app/workers/mailer_worker.rb b/spec/dummies/with-engine/dummy/app/workers/mailer_worker.rb
similarity index 100%
rename from spec/dummy/app/workers/mailer_worker.rb
rename to spec/dummies/with-engine/dummy/app/workers/mailer_worker.rb
diff --git a/spec/dummy/config/initializers/system.rb b/spec/dummies/with-engine/dummy/config/initializers/system.rb
similarity index 100%
rename from spec/dummy/config/initializers/system.rb
rename to spec/dummies/with-engine/dummy/config/initializers/system.rb
diff --git a/spec/dummy/config/locales/en.yml b/spec/dummies/with-engine/dummy/config/locales/en.yml
similarity index 100%
rename from spec/dummy/config/locales/en.yml
rename to spec/dummies/with-engine/dummy/config/locales/en.yml
diff --git a/spec/dummy/config/locales/pl.yml b/spec/dummies/with-engine/dummy/config/locales/pl.yml
similarity index 100%
rename from spec/dummy/config/locales/pl.yml
rename to spec/dummies/with-engine/dummy/config/locales/pl.yml
diff --git a/spec/dummies/with-engine/dummy/config/routes.rb b/spec/dummies/with-engine/dummy/config/routes.rb
new file mode 100644
index 0000000..356d4c7
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/config/routes.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+Rails.application.routes.draw do
+  mount SuperEngine::Engine, at: "super_engine"
+
+  get "users/show/:id" => "users#show"
+  get "users/new/:id" => "users#new"
+
+  get "safe_params_callbacks/show/:id" => "safe_params_callbacks#show"
+
+  get "/api/users/show/:id" => "api_users#show"
+  get "/api/users/new/:id" => "api_users#new"
+
+  get "/api/safe_params_callbacks/show/:id" => "api_safe_params_callbacks#show"
+end
diff --git a/spec/dummy/config/system/boot/persistence.rb b/spec/dummies/with-engine/dummy/config/system/boot/persistence.rb
similarity index 100%
rename from spec/dummy/config/system/boot/persistence.rb
rename to spec/dummies/with-engine/dummy/config/system/boot/persistence.rb
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/Gemfile b/spec/dummies/with-engine/dummy/engines/super_engine/Gemfile
new file mode 100644
index 0000000..7a51d15
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/Gemfile
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+# Declare your gem's dependencies in example_engine.gemspec.
+# Bundler will treat runtime dependencies like base dependencies, and
+# development dependencies will be added by default to the :development group.
+gemspec
+
+gem "dry-rails", path: "../../../../../.."
+
+# Declare any dependencies that are still in development here instead of in
+# your gemspec. These might include edge Rails or gems from your path or
+# Git. Remember to move these dependencies to your gemspec before releasing
+# your gem to rubygems.org.
+
+# To use a debugger
+# gem 'byebug', group: [:development, :test]
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/api_books_controller.rb b/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/api_books_controller.rb
new file mode 100644
index 0000000..8e15db8
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/api_books_controller.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+module SuperEngine
+  class ApiBooksController < ActionController::API
+    schema(:show) do
+      required(:id).value(:integer)
+    end
+
+    schema(:new) do
+      required(:id).value(:integer)
+    end
+
+    def show
+      if safe_params.success?
+        render json: {id: safe_params[:id], name: "Harry Potter"}
+      else
+        render json: {errors: safe_params.errors.to_h}
+      end
+    end
+
+    def new
+      if safe_params.success?
+        render json: {id: safe_params[:id], name: "Harry Potter"}
+      else
+        render json: {errors: safe_params.errors.to_h}
+      end
+    end
+  end
+end
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/api_safe_params_callbacks_controller.rb b/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/api_safe_params_callbacks_controller.rb
new file mode 100644
index 0000000..09bfca2
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/api_safe_params_callbacks_controller.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+module SuperEngine
+  class ApiSafeParamsCallbacksController < ActionController::API
+    before_action do
+      if safe_params&.failure?
+        head 422
+      else
+        head 200
+      end
+    end
+
+    schema(:show) do
+      required(:id).value(:integer)
+    end
+
+    def show; end
+  end
+end
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/application_controller.rb b/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/application_controller.rb
new file mode 100644
index 0000000..d755ce4
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/application_controller.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+module SuperEngine
+  class ApplicationController < ActionController::Base
+    protect_from_forgery with: :exception
+  end
+end
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/books_controller.rb b/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/books_controller.rb
new file mode 100644
index 0000000..759117f
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/books_controller.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+module SuperEngine
+  class BooksController < ApplicationController
+    schema(:show) do
+      required(:id).value(:integer)
+    end
+
+    schema(:new) do
+      required(:id).value(:integer)
+    end
+
+    def show
+      if safe_params.success?
+        render json: {id: safe_params[:id], name: "Harry Potter"}
+      else
+        render json: {errors: safe_params.errors.to_h}
+      end
+    end
+
+    def new
+      if safe_params.success?
+        render json: {id: safe_params[:id], name: "Harry Potter"}
+      else
+        render json: {errors: safe_params.errors.to_h}
+      end
+    end
+  end
+end
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/safe_params_callbacks_controller.rb b/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/safe_params_callbacks_controller.rb
new file mode 100644
index 0000000..dc891da
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/app/controllers/super_engine/safe_params_callbacks_controller.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+module SuperEngine
+  class SafeParamsCallbacksController < ApplicationController
+    before_action do
+      if safe_params&.failure?
+        head 422
+      else
+        head 200
+      end
+    end
+
+    schema(:show) do
+      required(:id).value(:integer)
+    end
+
+    def show; end
+  end
+end
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/app/forms/super_engine/create_book_form.rb b/spec/dummies/with-engine/dummy/engines/super_engine/app/forms/super_engine/create_book_form.rb
new file mode 100644
index 0000000..d771ded
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/app/forms/super_engine/create_book_form.rb
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+module SuperEngine
+  class CreateBookForm
+  end
+end
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/app/operations/super_engine/books/create.rb b/spec/dummies/with-engine/dummy/engines/super_engine/app/operations/super_engine/books/create.rb
new file mode 100644
index 0000000..5a5ed22
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/app/operations/super_engine/books/create.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+module SuperEngine
+  module Books
+    class Create
+    end
+  end
+end
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/config/routes.rb b/spec/dummies/with-engine/dummy/engines/super_engine/config/routes.rb
new file mode 100644
index 0000000..fa578a0
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/config/routes.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+SuperEngine::Engine.routes.draw do
+  get "books/show/:id" => "books#show"
+  get "books/new/:id" => "books#new"
+
+  get "safe_params_callbacks/show/:id" => "safe_params_callbacks#show"
+
+  get "/api/books/show/:id" => "api_books#show"
+  get "/api/books/new/:id" => "api_books#new"
+
+  get "/api/safe_params_callbacks/show/:id" => "api_safe_params_callbacks#show"
+end
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/config/system/.keep b/spec/dummies/with-engine/dummy/engines/super_engine/config/system/.keep
new file mode 100644
index 0000000..e69de29
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/lib/super_engine.rb b/spec/dummies/with-engine/dummy/engines/super_engine/lib/super_engine.rb
new file mode 100644
index 0000000..46b1428
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/lib/super_engine.rb
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+require "super_engine/engine"
+
+module SuperEngine
+end
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/lib/super_engine/engine.rb b/spec/dummies/with-engine/dummy/engines/super_engine/lib/super_engine/engine.rb
new file mode 100644
index 0000000..3408e4e
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/lib/super_engine/engine.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+require "dry-rails"
+
+module SuperEngine
+  class Engine < ::Rails::Engine
+    isolate_namespace SuperEngine
+
+    initializer "super_engine.dry-container" do |_app|
+      Dry::Rails::Engine.container(:super_engine) do
+        config.component_dirs.add "app/operations"
+      end
+    end
+
+    # This is needed because `finalize!` can reload code and this hook is called every-time
+    # in development env upon a request (in production it's called just once during booting)
+    config.to_prepare do
+      Engine.finalize!
+    end
+
+    # Code-reloading-aware finalization process
+    #
+    # This sets up `Container` and `Deps` constants, reloads them if this is in reloading mode,
+    # and registers default components like the railtie itself or the inflector
+    #
+    # @api public
+    #
+    delegate :finalize!, to: :finalizer
+    alias_method :reload, :finalize!
+
+    # Stops all configured features (bootable components)
+    #
+    # This is *crucial* when reloading code in development mode. Every bootable component
+    # should be able to clear the runtime from any constants that it created in its `stop`
+    # lifecycle step
+    #
+    # @api public
+    delegate :stop_features, to: :finalizer
+
+    # Exposes the container constant
+    #
+    # @return [Dry::Rails::Container]
+    #
+    # @api public
+    delegate :container, to: :finalizer
+
+    # @api private
+    delegate :set_or_reload, to: :finalizer
+
+    # @api private
+    delegate :remove_constant, to: :finalizer
+
+    private
+
+    def finalizer
+      @finalizer ||= Dry::Rails::Engine::Finalizer.new(
+        railtie: self,
+        app_namespace: SuperEngine,
+        root_path: ::Rails.root.join("engines/super_engine")
+      )
+    end
+  end
+end
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/lib/super_engine/version.rb b/spec/dummies/with-engine/dummy/engines/super_engine/lib/super_engine/version.rb
new file mode 100644
index 0000000..6aa8c9e
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/lib/super_engine/version.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+module SuperEngine
+  VERSION = "0.0.1"
+end
diff --git a/spec/dummies/with-engine/dummy/engines/super_engine/super_engine.gemspec b/spec/dummies/with-engine/dummy/engines/super_engine/super_engine.gemspec
new file mode 100644
index 0000000..8bb38a3
--- /dev/null
+++ b/spec/dummies/with-engine/dummy/engines/super_engine/super_engine.gemspec
@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+$LOAD_PATH.push File.expand_path("lib", __dir__)
+unless defined? RAILS_VERSION
+  RAILS_VERSION = ENV["RAILS_VERSION"] || "6.x"
+end
+
+# Maintain your gem's version:
+require "super_engine/version"
+
+# Describe your gem and declare its dependencies:
+Gem::Specification.new do |spec|
+  spec.name        = "super_engine"
+  spec.version     = SuperEngine::VERSION
+  spec.authors     = ["Krzysztof Zalewski"]
+  spec.email       = ["zlw.zalewski@gmail.com"]
+  spec.homepage    = ""
+  spec.summary     = ""
+  spec.description = ""
+  spec.required_ruby_version = ">= 2.6.0"
+
+  spec.files = Dir["{app,config,db,lib}/**/*", "MIT-LICENSE", "Rakefile", "README.md"]
+
+  spec.add_dependency "actionpack", "~> 6.0.2", ">= 6.0.2.1"
+  spec.add_dependency "dry-rails"
+end
diff --git a/spec/dummy/lib/dummy/notifier.rb b/spec/dummies/with-engine/dummy/lib/dummy/notifier.rb
similarity index 100%
rename from spec/dummy/lib/dummy/notifier.rb
rename to spec/dummies/with-engine/dummy/lib/dummy/notifier.rb
diff --git a/spec/dummy/lib/dummy/user_contract.rb b/spec/dummies/with-engine/dummy/lib/dummy/user_contract.rb
similarity index 100%
rename from spec/dummy/lib/dummy/user_contract.rb
rename to spec/dummies/with-engine/dummy/lib/dummy/user_contract.rb
diff --git a/spec/dummy/lib/mailer.rb b/spec/dummies/with-engine/dummy/lib/mailer.rb
similarity index 100%
rename from spec/dummy/lib/mailer.rb
rename to spec/dummies/with-engine/dummy/lib/mailer.rb
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/.rspec b/spec/dummies/without-engine/dummy-5.x/dummy/.rspec
new file mode 100644
index 0000000..4e1e0d2
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/.rspec
@@ -0,0 +1 @@
+--color
diff --git a/spec/dummy-5.x/dummy/Gemfile b/spec/dummies/without-engine/dummy-5.x/dummy/Gemfile
similarity index 100%
rename from spec/dummy-5.x/dummy/Gemfile
rename to spec/dummies/without-engine/dummy-5.x/dummy/Gemfile
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/app b/spec/dummies/without-engine/dummy-5.x/dummy/app
new file mode 120000
index 0000000..577fcba
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/app
@@ -0,0 +1 @@
+../../dummy/app
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/application.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/application.rb
new file mode 100644
index 0000000..31541ef
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/application.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+require_relative "boot"
+
+require "rails"
+require "action_controller/railtie"
+
+Bundler.setup(*Rails.groups)
+
+module Dummy
+  class Application < Rails::Application
+    config.root = Pathname(__dir__).join("..").realpath
+  end
+end
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/boot.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/boot.rb
new file mode 100644
index 0000000..c2241d7
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/boot.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+ENV["BUNDLE_GEMFILE"] ||= File.expand_path("../Gemfile", __dir__)
+
+require "bundler/setup" # Set up gems listed in the Gemfile.
diff --git a/spec/dummy-5.x/dummy/config/environment.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/environment.rb
similarity index 100%
rename from spec/dummy-5.x/dummy/config/environment.rb
rename to spec/dummies/without-engine/dummy-5.x/dummy/config/environment.rb
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/environments/development.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/environments/development.rb
new file mode 100644
index 0000000..609196a
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/environments/development.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+Rails.application.configure do
+  # Settings specified here will take precedence over those in config/application.rb.
+
+  # In the development environment your application's code is reloaded on
+  # every request. This slows down response time but is perfect for development
+  # since you don't have to restart the web server when you make code changes.
+  config.cache_classes = false
+
+  # Do not eager load code on boot.
+  config.eager_load = false
+
+  # Show full error reports.
+  config.consider_all_requests_local = true
+
+  # Enable/disable caching. By default caching is disabled.
+  if Rails.root.join("tmp/caching-dev.txt").exist?
+    config.action_controller.perform_caching = true
+
+    config.cache_store = :memory_store
+    config.public_file_server.headers = {
+      "Cache-Control" => "public, max-age=172800"
+    }
+  else
+    config.action_controller.perform_caching = false
+
+    config.cache_store = :null_store
+  end
+
+  # Print deprecation notices to the Rails logger.
+  config.active_support.deprecation = :log
+
+  # Raises error for missing translations
+  # config.action_view.raise_on_missing_translations = true
+
+  # Use an evented file watcher to asynchronously detect changes in source code,
+  # routes, locales, etc. This feature depends on the listen gem.
+  config.file_watcher = ActiveSupport::EventedFileUpdateChecker
+end
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/environments/production.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/environments/production.rb
new file mode 100644
index 0000000..b1ce01e
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/environments/production.rb
@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+Rails.application.configure do
+  # Settings specified here will take precedence over those in config/application.rb.
+
+  # Code is not reloaded between requests.
+  config.cache_classes = true
+
+  # Eager load code on boot. This eager loads most of Rails and
+  # your application in memory, allowing both threaded web servers
+  # and those relying on copy on write to perform better.
+  # Rake tasks automatically ignore this option for performance.
+  config.eager_load = true
+
+  # Full error reports are disabled and caching is turned on.
+  config.consider_all_requests_local       = false
+  config.action_controller.perform_caching = true
+
+  # Disable serving static files from the `/public` folder by default since
+  # Apache or NGINX already handles this.
+  config.public_file_server.enabled = ENV["RAILS_SERVE_STATIC_FILES"].present?
+
+  # Enable serving of images, stylesheets, and JavaScripts from an asset server.
+  # config.action_controller.asset_host = 'http://assets.example.com'
+
+  # Specifies the header that your server uses for sending files.
+  # config.action_dispatch.x_sendfile_header = 'X-Sendfile' # for Apache
+  # config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect' # for NGINX
+
+  # Force all access to the app over SSL, use Strict-Transport-Security, and use secure cookies.
+  # config.force_ssl = true
+
+  # Use the lowest log level to ensure availability of diagnostic information
+  # when problems arise.
+  config.log_level = :debug
+
+  # Prepend all log lines with the following tags.
+  config.log_tags = [:request_id]
+
+  # Use a different cache store in production.
+  # config.cache_store = :mem_cache_store
+
+  # Use a real queuing backend for Active Job (and separate queues per environment)
+  # config.active_job.queue_adapter     = :resque
+  # config.active_job.queue_name_prefix = "dummy_#{Rails.env}"
+
+  # Enable locale fallbacks for I18n (makes lookups for any locale fall back to
+  # the I18n.default_locale when a translation cannot be found).
+  config.i18n.fallbacks = true
+
+  # Send deprecation notices to registered listeners.
+  config.active_support.deprecation = :notify
+
+  # Use default logging formatter so that PID and timestamp are not suppressed.
+  config.log_formatter = ::Logger::Formatter.new
+
+  # Use a different logger for distributed setups.
+  # require 'syslog/logger'
+  # config.logger = ActiveSupport::TaggedLogging.new(Syslog::Logger.new 'app-name')
+
+  if ENV["RAILS_LOG_TO_STDOUT"].present?
+    logger           = ActiveSupport::Logger.new($stdout)
+    logger.formatter = config.log_formatter
+    config.logger = ActiveSupport::TaggedLogging.new(logger)
+  end
+end
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/environments/test.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/environments/test.rb
new file mode 100644
index 0000000..baba7fb
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/environments/test.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+Rails.application.configure do
+  # Settings specified here will take precedence over those in config/application.rb.
+
+  # The test environment is used exclusively to run your application's
+  # test suite. You never need to work with it otherwise. Remember that
+  # your test database is "scratch space" for the test suite and is wiped
+  # and recreated between test runs. Don't rely on the data there!
+  config.cache_classes = true
+
+  # Do not eager load code on boot. This avoids loading your whole application
+  # just for the purpose of running a single test. If you are using a tool that
+  # preloads Rails for running tests, you may have to set it to true.
+  config.eager_load = false
+
+  # Configure public file server for tests with Cache-Control for performance.
+  config.public_file_server.enabled = true
+  config.public_file_server.headers = {
+    "Cache-Control" => "public, max-age=3600"
+  }
+
+  # Show full error reports and disable caching.
+  config.consider_all_requests_local       = true
+  config.action_controller.perform_caching = false
+
+  # Raise exceptions instead of rendering exception templates.
+  config.action_dispatch.show_exceptions = false
+
+  # Disable request forgery protection in test environment.
+  config.action_controller.allow_forgery_protection = false
+
+  # Print deprecation notices to the stderr.
+  config.active_support.deprecation = :stderr
+
+  # Raises error for missing translations
+  # config.action_view.raise_on_missing_translations = true
+end
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/application_controller_renderer.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/application_controller_renderer.rb
new file mode 100644
index 0000000..6e2d5d2
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/application_controller_renderer.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# ApplicationController.renderer.defaults.merge!(
+#   http_host: 'example.org',
+#   https: false
+# )
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/backtrace_silencers.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/backtrace_silencers.rb
new file mode 100644
index 0000000..521758a
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/backtrace_silencers.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# You can add backtrace silencers for libraries that you're
+# using but don't wish to see in your backtraces.
+# Rails.backtrace_cleaner.add_silencer { |line| line =~ /my_noisy_library/ }
+
+# You can also remove all the silencers if you're trying to
+# debug a problem that might stem from framework code.
+# Rails.backtrace_cleaner.remove_silencers!
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/cookies_serializer.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/cookies_serializer.rb
new file mode 100644
index 0000000..ee8dff9
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/cookies_serializer.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# Specify a serializer for the signed and encrypted cookie jars.
+# Valid options are :json, :marshal, and :hybrid.
+Rails.application.config.action_dispatch.cookies_serializer = :json
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/filter_parameter_logging.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/filter_parameter_logging.rb
new file mode 100644
index 0000000..7a4f47b
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/filter_parameter_logging.rb
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# Configure sensitive parameters which will be filtered from the log file.
+Rails.application.config.filter_parameters += [:password]
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/inflections.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/inflections.rb
new file mode 100644
index 0000000..dc84742
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/inflections.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# Add new inflection rules using the following format. Inflections
+# are locale specific, and you may define rules for as many different
+# locales as you wish. All of these examples are active by default:
+# ActiveSupport::Inflector.inflections(:en) do |inflect|
+#   inflect.plural /^(ox)$/i, '\1en'
+#   inflect.singular /^(ox)en/i, '\1'
+#   inflect.irregular 'person', 'people'
+#   inflect.uncountable %w( fish sheep )
+# end
+
+# These inflection rules are supported but not enabled by default:
+# ActiveSupport::Inflector.inflections(:en) do |inflect|
+#   inflect.acronym 'RESTful'
+# end
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/mime_types.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/mime_types.rb
new file mode 100644
index 0000000..be6fedc
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/mime_types.rb
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# Add new mime types for use in respond_to blocks:
+# Mime::Type.register "text/richtext", :rtf
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/new_framework_defaults.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/new_framework_defaults.rb
new file mode 100644
index 0000000..cc06b3f
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/new_framework_defaults.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+#
+# This file contains migration options to ease your Rails 5.0 upgrade.
+#
+# Read the Rails 5.0 release notes for more info on each option.
+
+# Enable per-form CSRF tokens. Previous versions had false.
+Rails.application.config.action_controller.per_form_csrf_tokens = true
+
+# Enable origin-checking CSRF mitigation. Previous versions had false.
+Rails.application.config.action_controller.forgery_protection_origin_check = true
+
+# Make Ruby 2.4 preserve the timezone of the receiver when calling `to_time`.
+# Previous versions had false.
+ActiveSupport.to_time_preserves_timezone = true
+
+# Configure SSL options to enable HSTS with subdomains. Previous versions had false.
+Rails.application.config.ssl_options = {hsts: {subdomains: true}}
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/session_store.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/session_store.rb
new file mode 100644
index 0000000..606745f
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/session_store.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+Rails.application.config.session_store :cookie_store, key: "_dummy_session"
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/system.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/system.rb
new file mode 120000
index 0000000..cd46fbe
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/system.rb
@@ -0,0 +1 @@
+../../../../dummy/config/initializers/system.rb
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/wrap_parameters.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/wrap_parameters.rb
new file mode 100644
index 0000000..e7148a3
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/initializers/wrap_parameters.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# This file contains settings for ActionController::ParamsWrapper which
+# is enabled by default.
+
+# Enable parameter wrapping for JSON. You can disable this by setting :format to an empty array.
+ActiveSupport.on_load(:action_controller) do
+  wrap_parameters format: [:json]
+end
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/locales b/spec/dummies/without-engine/dummy-5.x/dummy/config/locales
new file mode 120000
index 0000000..f6517ee
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/locales
@@ -0,0 +1 @@
+../../../dummy/config/locales
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/routes.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/routes.rb
new file mode 120000
index 0000000..b096837
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/routes.rb
@@ -0,0 +1 @@
+../../../dummy/config/routes.rb
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/secrets.yml b/spec/dummies/without-engine/dummy-5.x/dummy/config/secrets.yml
new file mode 100644
index 0000000..319f3b7
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/secrets.yml
@@ -0,0 +1,22 @@
+# Be sure to restart your server when you modify this file.
+
+# Your secret key is used for verifying the integrity of signed cookies.
+# If you change this key, all old signed cookies will become invalid!
+
+# Make sure the secret is at least 30 characters and all random,
+# no regular words or you'll be exposed to dictionary attacks.
+# You can use `rails secret` to generate a secure secret key.
+
+# Make sure the secrets in this file are kept private
+# if you're sharing your code publicly.
+
+development:
+  secret_key_base: 93cc56a5c8991ad66f5a0ad2fa901a680d33b4d2b2556737115113246700705a46122df56d060d3da333778569e9bd5a0a0e8c21693cd10c48ad496db33edffd
+
+test:
+  secret_key_base: 3040bb7ecbe834a675144408fc988bdaa791f78e9a9df2493665d514e25b8e409644e65194e070f903d18a03cd01e9463d0d562bb50bfbb7ba9dc8d0aef2076b
+
+# Do not keep production secrets in the repository,
+# instead read values from the environment.
+production:
+  secret_key_base: <%= ENV["SECRET_KEY_BASE"] %>
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/spring.rb b/spec/dummies/without-engine/dummy-5.x/dummy/config/spring.rb
new file mode 100644
index 0000000..c5933e4
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/spring.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+%w[
+  .ruby-version
+  .rbenv-vars
+  tmp/restart.txt
+  tmp/caching-dev.txt
+].each { |path| Spring.watch(path) }
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/config/system b/spec/dummies/without-engine/dummy-5.x/dummy/config/system
new file mode 120000
index 0000000..ac170f3
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/config/system
@@ -0,0 +1 @@
+../../../dummy/config/system
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/lib b/spec/dummies/without-engine/dummy-5.x/dummy/lib
new file mode 120000
index 0000000..40a291b
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-5.x/dummy/lib
@@ -0,0 +1 @@
+../../dummy/lib
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-5.x/dummy/log/.keep b/spec/dummies/without-engine/dummy-5.x/dummy/log/.keep
new file mode 100644
index 0000000..e69de29
diff --git a/spec/dummy-6.x/dummy/Gemfile b/spec/dummies/without-engine/dummy-6.x/dummy/Gemfile
similarity index 100%
rename from spec/dummy-6.x/dummy/Gemfile
rename to spec/dummies/without-engine/dummy-6.x/dummy/Gemfile
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/app b/spec/dummies/without-engine/dummy-6.x/dummy/app
new file mode 120000
index 0000000..577fcba
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/app
@@ -0,0 +1 @@
+../../dummy/app
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/application.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/application.rb
new file mode 100644
index 0000000..cc52713
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/application.rb
@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+require_relative "boot"
+
+require "rails"
+require "action_controller/railtie"
+require "action_view/railtie"
+
+# Require the gems listed in Gemfile, including any gems
+# you've limited to :test, :development, or :production.
+Bundler.require(*Rails.groups)
+
+module Dummy
+  class Application < Rails::Application
+    # Initialize configuration defaults for originally generated Rails version.
+    config.load_defaults 6.0
+
+    config.root = Pathname(__dir__).join("..").realpath
+
+    # Settings in config/environments/* take precedence over those specified here.
+    # Application configuration can go into files in config/initializers
+    # -- all .rb files in that directory are automatically loaded after loading
+    # the framework and any gems in your application.
+
+    # Don't generate system test files.
+    config.generators.system_tests = nil
+  end
+end
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/boot.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/boot.rb
new file mode 100644
index 0000000..c2241d7
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/boot.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+ENV["BUNDLE_GEMFILE"] ||= File.expand_path("../Gemfile", __dir__)
+
+require "bundler/setup" # Set up gems listed in the Gemfile.
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/credentials.yml.enc b/spec/dummies/without-engine/dummy-6.x/dummy/config/credentials.yml.enc
new file mode 100644
index 0000000..8f86f0f
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/credentials.yml.enc
@@ -0,0 +1 @@
+gQ0RauBY7+ysf9CEmGsMv3Qcd4FcdU/iCsHSy8GQOA3b5LvtWit8mLybKKNPT5Nua2kL1WWoUB2nvKYEMWcYVFwaMCgmygmslkY8GYgqQJYFd+L7NDC3xeJ8twc/7rih+CcnIQzWseVDSqJX16PwedAiH54UsP9OkLTONL0mOWGYNPnoXeAjnXLgYYekkBE+iwhapGFc7hfQ8QG4PvKKG5EkLDzAFkpGrGrxQ3Fzt2hLCRJ1MPF+qs0hqEYXcJ8lsuKFrH5GzumPWeQEI5saCm0RxfKfVCSP3FHUUnI4Rr9zyrWUcOzbaxs8NWg5QaG9qy75Q4I1gMRoAlIjUuMpQeir4i0njkpWeGVh5tjzRv6t42wlrx3SN1BwAVgbWIldNilNfJqb6KPvmT2Sshigb5Z0tGt042Jj9hDL--UtdTCgDlI7AAkKTI--7sR0UgSU0TcMcoYdCsKUdw==
\ No newline at end of file
diff --git a/spec/dummy-6.x/dummy/config/environment.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/environment.rb
similarity index 100%
rename from spec/dummy-6.x/dummy/config/environment.rb
rename to spec/dummies/without-engine/dummy-6.x/dummy/config/environment.rb
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/environments/development.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/environments/development.rb
new file mode 100644
index 0000000..6351e50
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/environments/development.rb
@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+Rails.application.configure do
+  # Settings specified here will take precedence over those in config/application.rb.
+
+  # In the development environment your application's code is reloaded on
+  # every request. This slows down response time but is perfect for development
+  # since you don't have to restart the web server when you make code changes.
+  config.cache_classes = false
+
+  # Do not eager load code on boot.
+  config.eager_load = false
+
+  # Show full error reports.
+  config.consider_all_requests_local = true
+
+  # Enable/disable caching. By default caching is disabled.
+  # Run rails dev:cache to toggle caching.
+  if Rails.root.join("tmp", "caching-dev.txt").exist?
+    config.action_controller.perform_caching = true
+    config.action_controller.enable_fragment_cache_logging = true
+
+    config.cache_store = :memory_store
+    config.public_file_server.headers = {
+      "Cache-Control" => "public, max-age=#{2.days.to_i}"
+    }
+  else
+    config.action_controller.perform_caching = false
+
+    config.cache_store = :null_store
+  end
+
+  # Print deprecation notices to the Rails logger.
+  config.active_support.deprecation = :log
+
+  # Raises error for missing translations.
+  # config.action_view.raise_on_missing_translations = true
+
+  # Use an evented file watcher to asynchronously detect changes in source code,
+  # routes, locales, etc. This feature depends on the listen gem.
+  config.file_watcher = ActiveSupport::EventedFileUpdateChecker
+end
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/environments/production.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/environments/production.rb
new file mode 100644
index 0000000..671f6d2
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/environments/production.rb
@@ -0,0 +1,91 @@
+# frozen_string_literal: true
+
+Rails.application.configure do
+  # Settings specified here will take precedence over those in config/application.rb.
+
+  # Code is not reloaded between requests.
+  config.cache_classes = true
+
+  # Eager load code on boot. This eager loads most of Rails and
+  # your application in memory, allowing both threaded web servers
+  # and those relying on copy on write to perform better.
+  # Rake tasks automatically ignore this option for performance.
+  config.eager_load = true
+
+  # Full error reports are disabled and caching is turned on.
+  config.consider_all_requests_local       = false
+  config.action_controller.perform_caching = true
+
+  # Ensures that a master key has been made available in either ENV["RAILS_MASTER_KEY"]
+  # or in config/master.key. This key is used to decrypt credentials (and other encrypted files).
+  # config.require_master_key = true
+
+  # Disable serving static files from the `/public` folder by default since
+  # Apache or NGINX already handles this.
+  config.public_file_server.enabled = ENV["RAILS_SERVE_STATIC_FILES"].present?
+
+  # Enable serving of images, stylesheets, and JavaScripts from an asset server.
+  # config.action_controller.asset_host = 'http://assets.example.com'
+
+  # Specifies the header that your server uses for sending files.
+  # config.action_dispatch.x_sendfile_header = 'X-Sendfile' # for Apache
+  # config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect' # for NGINX
+
+  # Force all access to the app over SSL, use Strict-Transport-Security, and use secure cookies.
+  # config.force_ssl = true
+
+  # Use the lowest log level to ensure availability of diagnostic information
+  # when problems arise.
+  config.log_level = :debug
+
+  # Prepend all log lines with the following tags.
+  config.log_tags = [:request_id]
+
+  # Use a different cache store in production.
+  # config.cache_store = :mem_cache_store
+
+  # Use a real queuing backend for Active Job (and separate queues per environment).
+  # config.active_job.queue_adapter     = :resque
+  # config.active_job.queue_name_prefix = "dummy_production"
+
+  # Enable locale fallbacks for I18n (makes lookups for any locale fall back to
+  # the I18n.default_locale when a translation cannot be found).
+  config.i18n.fallbacks = true
+
+  # Send deprecation notices to registered listeners.
+  config.active_support.deprecation = :notify
+
+  # Use default logging formatter so that PID and timestamp are not suppressed.
+  config.log_formatter = ::Logger::Formatter.new
+
+  # Use a different logger for distributed setups.
+  # require 'syslog/logger'
+  # config.logger = ActiveSupport::TaggedLogging.new(Syslog::Logger.new 'app-name')
+
+  if ENV["RAILS_LOG_TO_STDOUT"].present?
+    logger           = ActiveSupport::Logger.new($stdout)
+    logger.formatter = config.log_formatter
+    config.logger    = ActiveSupport::TaggedLogging.new(logger)
+  end
+
+  # Inserts middleware to perform automatic connection switching.
+  # The `database_selector` hash is used to pass options to the DatabaseSelector
+  # middleware. The `delay` is used to determine how long to wait after a write
+  # to send a subsequent read to the primary.
+  #
+  # The `database_resolver` class is used by the middleware to determine which
+  # database is appropriate to use based on the time delay.
+  #
+  # The `database_resolver_context` class is used by the middleware to set
+  # timestamps for the last write to the primary. The resolver uses the context
+  # class timestamps to determine how long to wait before reading from the
+  # replica.
+  #
+  # By default Rails will store a last write timestamp in the session. The
+  # DatabaseSelector middleware is designed as such you can define your own
+  # strategy for connection switching and pass that into the middleware through
+  # these configuration options.
+  # config.active_record.database_selector = { delay: 2.seconds }
+  # config.active_record.database_resolver = ActiveRecord::Middleware::DatabaseSelector::Resolver
+  # config.active_record.database_resolver_context = ActiveRecord::Middleware::DatabaseSelector::Resolver::Session
+end
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/environments/test.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/environments/test.rb
new file mode 100644
index 0000000..c045a26
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/environments/test.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+# The test environment is used exclusively to run your application's
+# test suite. You never need to work with it otherwise. Remember that
+# your test database is "scratch space" for the test suite and is wiped
+# and recreated between test runs. Don't rely on the data there!
+
+Rails.application.configure do
+  # Settings specified here will take precedence over those in config/application.rb.
+
+  config.cache_classes = false
+
+  # Do not eager load code on boot. This avoids loading your whole application
+  # just for the purpose of running a single test. If you are using a tool that
+  # preloads Rails for running tests, you may have to set it to true.
+  config.eager_load = false
+
+  # Configure public file server for tests with Cache-Control for performance.
+  config.public_file_server.enabled = true
+  config.public_file_server.headers = {
+    "Cache-Control" => "public, max-age=3600"
+  }
+
+  # Show full error reports and disable caching.
+  config.consider_all_requests_local       = true
+  config.action_controller.perform_caching = false
+  config.cache_store = :null_store
+
+  # Raise exceptions instead of rendering exception templates.
+  config.action_dispatch.show_exceptions = false
+
+  # Disable request forgery protection in test environment.
+  config.action_controller.allow_forgery_protection = false
+
+  # Print deprecation notices to the stderr.
+  config.active_support.deprecation = :stderr
+
+  # Raises error for missing translations.
+  # config.action_view.raise_on_missing_translations = true
+end
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/application_controller_renderer.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/application_controller_renderer.rb
new file mode 100644
index 0000000..6d56e43
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/application_controller_renderer.rb
@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# ActiveSupport::Reloader.to_prepare do
+#   ApplicationController.renderer.defaults.merge!(
+#     http_host: 'example.org',
+#     https: false
+#   )
+# end
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/backtrace_silencers.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/backtrace_silencers.rb
new file mode 100644
index 0000000..4b63f28
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/backtrace_silencers.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# You can add backtrace silencers for libraries that you're using but don't wish to see in your backtraces.
+# Rails.backtrace_cleaner.add_silencer { |line| line =~ /my_noisy_library/ }
+
+# You can also remove all the silencers if you're trying to debug a problem that might stem from framework code.
+# Rails.backtrace_cleaner.remove_silencers!
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/content_security_policy.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/content_security_policy.rb
new file mode 100644
index 0000000..87fd451
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/content_security_policy.rb
@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# Define an application-wide content security policy
+# For further information see the following documentation
+# https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy
+
+# Rails.application.config.content_security_policy do |policy|
+#   policy.default_src :self, :https
+#   policy.font_src    :self, :https, :data
+#   policy.img_src     :self, :https, :data
+#   policy.object_src  :none
+#   policy.script_src  :self, :https
+#   policy.style_src   :self, :https
+
+#   # Specify URI for violation reports
+#   # policy.report_uri "/csp-violation-report-endpoint"
+# end
+
+# If you are using UJS then enable automatic nonce generation
+# Rails.application.config.content_security_policy_nonce_generator = -> request { SecureRandom.base64(16) }
+
+# Set the nonce only to specific directives
+# Rails.application.config.content_security_policy_nonce_directives = %w(script-src)
+
+# Report CSP violations to a specified URI
+# For further information see the following documentation:
+# https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy-Report-Only
+# Rails.application.config.content_security_policy_report_only = true
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/cookies_serializer.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/cookies_serializer.rb
new file mode 100644
index 0000000..ee8dff9
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/cookies_serializer.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# Specify a serializer for the signed and encrypted cookie jars.
+# Valid options are :json, :marshal, and :hybrid.
+Rails.application.config.action_dispatch.cookies_serializer = :json
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/filter_parameter_logging.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/filter_parameter_logging.rb
new file mode 100644
index 0000000..7a4f47b
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/filter_parameter_logging.rb
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# Configure sensitive parameters which will be filtered from the log file.
+Rails.application.config.filter_parameters += [:password]
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/inflections.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/inflections.rb
new file mode 100644
index 0000000..dc84742
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/inflections.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# Add new inflection rules using the following format. Inflections
+# are locale specific, and you may define rules for as many different
+# locales as you wish. All of these examples are active by default:
+# ActiveSupport::Inflector.inflections(:en) do |inflect|
+#   inflect.plural /^(ox)$/i, '\1en'
+#   inflect.singular /^(ox)en/i, '\1'
+#   inflect.irregular 'person', 'people'
+#   inflect.uncountable %w( fish sheep )
+# end
+
+# These inflection rules are supported but not enabled by default:
+# ActiveSupport::Inflector.inflections(:en) do |inflect|
+#   inflect.acronym 'RESTful'
+# end
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/mime_types.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/mime_types.rb
new file mode 100644
index 0000000..be6fedc
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/mime_types.rb
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# Add new mime types for use in respond_to blocks:
+# Mime::Type.register "text/richtext", :rtf
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/system.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/system.rb
new file mode 120000
index 0000000..cd46fbe
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/system.rb
@@ -0,0 +1 @@
+../../../../dummy/config/initializers/system.rb
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/wrap_parameters.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/wrap_parameters.rb
new file mode 100644
index 0000000..e7148a3
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/initializers/wrap_parameters.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+
+# This file contains settings for ActionController::ParamsWrapper which
+# is enabled by default.
+
+# Enable parameter wrapping for JSON. You can disable this by setting :format to an empty array.
+ActiveSupport.on_load(:action_controller) do
+  wrap_parameters format: [:json]
+end
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/locales b/spec/dummies/without-engine/dummy-6.x/dummy/config/locales
new file mode 120000
index 0000000..f6517ee
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/locales
@@ -0,0 +1 @@
+../../../dummy/config/locales
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/master.key b/spec/dummies/without-engine/dummy-6.x/dummy/config/master.key
new file mode 100644
index 0000000..b933e58
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/master.key
@@ -0,0 +1 @@
+4fea9f11ee0a627b125c0fd8df6ebab5
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/routes.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/routes.rb
new file mode 120000
index 0000000..b096837
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/routes.rb
@@ -0,0 +1 @@
+../../../dummy/config/routes.rb
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/spring.rb b/spec/dummies/without-engine/dummy-6.x/dummy/config/spring.rb
new file mode 100644
index 0000000..37a3543
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/spring.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+Spring.watch(
+  ".ruby-version",
+  ".rbenv-vars",
+  "tmp/restart.txt",
+  "tmp/caching-dev.txt"
+)
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/config/system b/spec/dummies/without-engine/dummy-6.x/dummy/config/system
new file mode 120000
index 0000000..ac170f3
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/config/system
@@ -0,0 +1 @@
+../../../dummy/config/system
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/lib b/spec/dummies/without-engine/dummy-6.x/dummy/lib
new file mode 120000
index 0000000..40a291b
--- /dev/null
+++ b/spec/dummies/without-engine/dummy-6.x/dummy/lib
@@ -0,0 +1 @@
+../../dummy/lib
\ No newline at end of file
diff --git a/spec/dummies/without-engine/dummy-6.x/dummy/log/.keep b/spec/dummies/without-engine/dummy-6.x/dummy/log/.keep
new file mode 100644
index 0000000..e69de29
diff --git a/spec/dummies/without-engine/dummy/app/controllers/api_safe_params_callbacks_controller.rb b/spec/dummies/without-engine/dummy/app/controllers/api_safe_params_callbacks_controller.rb
new file mode 100644
index 0000000..0d7699d
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/app/controllers/api_safe_params_callbacks_controller.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class ApiSafeParamsCallbacksController < ActionController::API
+  before_action do
+    if safe_params&.failure?
+      head 422
+    else
+      head 200
+    end
+  end
+
+  schema(:show) do
+    required(:id).value(:integer)
+  end
+
+  def show; end
+end
diff --git a/spec/dummies/without-engine/dummy/app/controllers/api_users_controller.rb b/spec/dummies/without-engine/dummy/app/controllers/api_users_controller.rb
new file mode 100644
index 0000000..18bb0e2
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/app/controllers/api_users_controller.rb
@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+class ApiUsersController < ActionController::API
+  schema(:show) do
+    required(:id).value(:integer)
+  end
+
+  schema(:new) do
+    required(:id).value(:integer)
+  end
+
+  def show
+    if safe_params.success?
+      render json: {id: safe_params[:id], name: "Jane"}
+    else
+      render json: {errors: safe_params.errors.to_h}
+    end
+  end
+
+  def new
+    if safe_params.success?
+      render json: {id: safe_params[:id], name: "Jane"}
+    else
+      render json: {errors: safe_params.errors.to_h}
+    end
+  end
+end
diff --git a/spec/dummies/without-engine/dummy/app/controllers/application_controller.rb b/spec/dummies/without-engine/dummy/app/controllers/application_controller.rb
new file mode 100644
index 0000000..280cc28
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/app/controllers/application_controller.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class ApplicationController < ActionController::Base
+  protect_from_forgery with: :exception
+end
diff --git a/spec/dummies/without-engine/dummy/app/controllers/safe_params_callbacks_controller.rb b/spec/dummies/without-engine/dummy/app/controllers/safe_params_callbacks_controller.rb
new file mode 100644
index 0000000..3852d86
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/app/controllers/safe_params_callbacks_controller.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class SafeParamsCallbacksController < ApplicationController
+  before_action do
+    if safe_params&.failure?
+      head 422
+    else
+      head 200
+    end
+  end
+
+  schema(:show) do
+    required(:id).value(:integer)
+  end
+
+  def show; end
+end
diff --git a/spec/dummies/without-engine/dummy/app/controllers/users_controller.rb b/spec/dummies/without-engine/dummy/app/controllers/users_controller.rb
new file mode 100644
index 0000000..19c4089
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/app/controllers/users_controller.rb
@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+class UsersController < ApplicationController
+  schema(:show) do
+    required(:id).value(:integer)
+  end
+
+  schema(:new) do
+    required(:id).value(:integer)
+  end
+
+  def show
+    if safe_params.success?
+      render json: {id: safe_params[:id], name: "Jane"}
+    else
+      render json: {errors: safe_params.errors.to_h}
+    end
+  end
+
+  def new
+    if safe_params.success?
+      render json: {id: safe_params[:id], name: "Jane"}
+    else
+      render json: {errors: safe_params.errors.to_h}
+    end
+  end
+end
diff --git a/spec/dummies/without-engine/dummy/app/forms/create_user_form.rb b/spec/dummies/without-engine/dummy/app/forms/create_user_form.rb
new file mode 100644
index 0000000..0b928fc
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/app/forms/create_user_form.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+class CreateUserForm
+end
diff --git a/spec/dummies/without-engine/dummy/app/models/container.rb b/spec/dummies/without-engine/dummy/app/models/container.rb
new file mode 100644
index 0000000..f028c32
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/app/models/container.rb
@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+class Container; end
diff --git a/spec/dummies/without-engine/dummy/app/models/user_repo.rb b/spec/dummies/without-engine/dummy/app/models/user_repo.rb
new file mode 100644
index 0000000..35b38f0
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/app/models/user_repo.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class UserRepo
+  include Dummy::Deps["persistence.db"]
+end
diff --git a/spec/dummies/without-engine/dummy/app/operations/create_user.rb b/spec/dummies/without-engine/dummy/app/operations/create_user.rb
new file mode 100644
index 0000000..75bff97
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/app/operations/create_user.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+class CreateUser
+end
diff --git a/spec/dummies/without-engine/dummy/app/services/github.rb b/spec/dummies/without-engine/dummy/app/services/github.rb
new file mode 100644
index 0000000..2823203
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/app/services/github.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+class Github
+end
diff --git a/spec/dummies/without-engine/dummy/app/workers/mailer_worker.rb b/spec/dummies/without-engine/dummy/app/workers/mailer_worker.rb
new file mode 100644
index 0000000..5909c7c
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/app/workers/mailer_worker.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class MailerWorker
+  include Dummy::Deps["mailer"]
+end
diff --git a/spec/dummies/without-engine/dummy/config/initializers/system.rb b/spec/dummies/without-engine/dummy/config/initializers/system.rb
new file mode 100644
index 0000000..2e7ceba
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/config/initializers/system.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require "dry/rails"
+
+Dry::Rails.container do
+  config.component_dirs.add "lib" do |dir|
+    dir.default_namespace = "dummy"
+  end
+
+  config.component_dirs.add "app/operations"
+  config.component_dirs.add "app/services"
+  config.component_dirs.add("app/workers") do |dir|
+    dir.memoize = true
+  end
+end
diff --git a/spec/dummies/without-engine/dummy/config/locales/en.yml b/spec/dummies/without-engine/dummy/config/locales/en.yml
new file mode 100644
index 0000000..20b4827
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/config/locales/en.yml
@@ -0,0 +1,4 @@
+en:
+  contracts:
+    errors:
+      filled?: 'cannot be blank'
diff --git a/spec/dummies/without-engine/dummy/config/locales/pl.yml b/spec/dummies/without-engine/dummy/config/locales/pl.yml
new file mode 100644
index 0000000..c42e330
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/config/locales/pl.yml
@@ -0,0 +1,4 @@
+pl:
+  contracts:
+    errors:
+      filled?: 'nie może być puste'
diff --git a/spec/dummy/config/routes.rb b/spec/dummies/without-engine/dummy/config/routes.rb
similarity index 100%
rename from spec/dummy/config/routes.rb
rename to spec/dummies/without-engine/dummy/config/routes.rb
diff --git a/spec/dummies/without-engine/dummy/config/system/boot/persistence.rb b/spec/dummies/without-engine/dummy/config/system/boot/persistence.rb
new file mode 100644
index 0000000..884fb4a
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/config/system/boot/persistence.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+Dummy::Container.boot(:persistence) do |container|
+  start do
+    container.register("persistence.db", :i_am_db)
+  end
+end
diff --git a/spec/dummies/without-engine/dummy/lib/dummy/notifier.rb b/spec/dummies/without-engine/dummy/lib/dummy/notifier.rb
new file mode 100644
index 0000000..30e4a96
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/lib/dummy/notifier.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+module Dummy
+  class Notifier
+    include Deps[:mailer]
+  end
+end
diff --git a/spec/dummies/without-engine/dummy/lib/dummy/user_contract.rb b/spec/dummies/without-engine/dummy/lib/dummy/user_contract.rb
new file mode 100644
index 0000000..0e12a35
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/lib/dummy/user_contract.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+module Dummy
+  class UserContract < ApplicationContract
+    params do
+      required(:name).filled(:string)
+    end
+  end
+end
diff --git a/spec/dummies/without-engine/dummy/lib/mailer.rb b/spec/dummies/without-engine/dummy/lib/mailer.rb
new file mode 100644
index 0000000..1f0b195
--- /dev/null
+++ b/spec/dummies/without-engine/dummy/lib/mailer.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+class Mailer
+end
diff --git a/spec/integration/dry/rails/railtie/finalize_engine_spec.rb b/spec/integration/dry/rails/railtie/finalize_engine_spec.rb
new file mode 100644
index 0000000..826e9c5
--- /dev/null
+++ b/spec/integration/dry/rails/railtie/finalize_engine_spec.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+RSpec.describe Dry::Rails::Railtie, ".finalize!", :engine do
+  subject(:railtie) { Dry::Rails::Railtie.instance }
+
+  it "reloads container and import module", no_reload: true do
+    Rails.application.reloader.reload!
+
+    Dry::Rails.container do
+      config.component_dirs.add "app/forms"
+    end
+
+    Dry::Rails::Engine.container(:super_engine) do
+      config.component_dirs.add "app/forms" do |dir|
+        dir.default_namespace = "super_engine"
+      end
+    end
+
+    Dummy::Container.register("foo", Object.new)
+    SuperEngine::Container.register("bar", Object.new)
+
+    expect(Dummy::Container.keys).to include("foo")
+    expect(SuperEngine::Container.keys).to include("bar")
+
+    Rails.application.reloader.reload!
+
+    expect(Dummy::Container.keys).to_not include("foo")
+    expect(SuperEngine::Container.keys).to_not include("bar")
+
+    klass = Class.new do
+      include Dummy::Deps["create_user_form"]
+      include SuperEngine::Deps["create_book_form"]
+    end
+
+    obj = klass.new
+
+    expect(obj.create_user_form).to be_instance_of(CreateUserForm)
+    expect(obj.create_book_form).to be_instance_of(SuperEngine::CreateBookForm)
+  end
+end
diff --git a/spec/integration/dry/rails/railtie/finalize_spec.rb b/spec/integration/dry/rails/railtie/finalize_spec.rb
index 8608e80..5c59369 100644
--- a/spec/integration/dry/rails/railtie/finalize_spec.rb
+++ b/spec/integration/dry/rails/railtie/finalize_spec.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-RSpec.describe Dry::Rails::Railtie, ".finalize!" do
+RSpec.describe Dry::Rails::Railtie, ".finalize!", :main_app do
   subject(:railtie) { Dry::Rails::Railtie.instance }
 
   it "reloads container and import module", no_reload: true do
diff --git a/spec/requests/engine/api_books_spec.rb b/spec/requests/engine/api_books_spec.rb
new file mode 100644
index 0000000..069790b
--- /dev/null
+++ b/spec/requests/engine/api_books_spec.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+RSpec.describe "SuperEngine::ApiBooksController", :engine, type: :request do
+  %w[show new].each do |action|
+    describe "GET /api/users/#{action}" do
+      it "returns a successful response" do
+        get "/super_engine/api/books/#{action}/312"
+
+        json = JSON.parse(response.body, symbolize_names: true)
+
+        expect(json[:id]).to be(312)
+        expect(json[:name]).to eql("Harry Potter")
+      end
+
+      it "returns errors" do
+        get "/super_engine/api/books/#{action}/oops"
+
+        json = JSON.parse(response.body, symbolize_names: true)
+
+        expect(json[:errors]).to eql(id: ["must be an integer"])
+      end
+    end
+  end
+end
diff --git a/spec/requests/engine/api_safe_params_callbacks_spec.rb b/spec/requests/engine/api_safe_params_callbacks_spec.rb
new file mode 100644
index 0000000..8f6476a
--- /dev/null
+++ b/spec/requests/engine/api_safe_params_callbacks_spec.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+RSpec.describe "SuperEngine::ApiSafeParamsCallbacksController", :engine, type: :request do
+  describe "GET /api/safe_params_callbacks/show" do
+    it "returns a successful response code" do
+      get "/super_engine/api/safe_params_callbacks/show/312"
+
+      expect(response).to have_http_status(200)
+    end
+
+    it "returns errors" do
+      get "/super_engine/api/safe_params_callbacks/show/oops"
+
+      expect(response).to have_http_status(422)
+    end
+  end
+end
diff --git a/spec/requests/engine/books_spec.rb b/spec/requests/engine/books_spec.rb
new file mode 100644
index 0000000..16c5b76
--- /dev/null
+++ b/spec/requests/engine/books_spec.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+RSpec.describe "SuperEngine::BooksController", :engine, type: :request do
+  %w[show new].each do |action|
+    describe "GET /users/#{action}" do
+      it "returns a successful response" do
+        get "/super_engine/books/#{action}/312"
+
+        json = JSON.parse(response.body, symbolize_names: true)
+
+        expect(json[:id]).to be(312)
+        expect(json[:name]).to eql("Harry Potter")
+      end
+
+      it "returns errors" do
+        get "/super_engine/books/#{action}/oops"
+
+        json = JSON.parse(response.body, symbolize_names: true)
+
+        expect(json[:errors]).to eql(id: ["must be an integer"])
+      end
+    end
+  end
+end
diff --git a/spec/requests/engine/safe_params_callbacks_spec.rb b/spec/requests/engine/safe_params_callbacks_spec.rb
new file mode 100644
index 0000000..575f36b
--- /dev/null
+++ b/spec/requests/engine/safe_params_callbacks_spec.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+RSpec.describe "SuperEngine::SafeParamsCallbacksController", :engine, type: :request do
+  describe "GET /safe_params_callbacks/show" do
+    it "returns a successful response code" do
+      get "/super_engine/safe_params_callbacks/show/312"
+
+      expect(response).to have_http_status(200)
+    end
+
+    it "returns errors" do
+      get "/super_engine/safe_params_callbacks/show/oops"
+
+      expect(response).to have_http_status(422)
+    end
+  end
+end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 98cc8b2..f47a23e 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -15,12 +15,20 @@
 ENV["RAILS_ENV"] ||= "test"
 
 RAILS_VERSION = ENV["RAILS_VERSION"] || "6.x"
+WITH_ENGINE = (ENV["WITH_ENGINE"] || "true") == "true"
+DUMMY_DIR = WITH_ENGINE ? "with-engine" : "without-engine"
+require SPEC_ROOT.join("dummies/#{DUMMY_DIR}/dummy-#{RAILS_VERSION}/dummy/config/environment").to_s
 
-require SPEC_ROOT.join("dummy-#{RAILS_VERSION}/dummy/config/environment").to_s
 
 require "rspec/rails"
 
 RSpec.configure do |config|
+  if WITH_ENGINE
+    config.filter_run_excluding main_app: true
+  else
+    config.filter_run_excluding engine:   true
+  end
+
   config.disable_monkey_patching!
 
   config.before do |example|