```ruby
module Konacha
  class Engine < Rails::Engine
    # Do not mess up the application's namespace.
    # http://api.rubyonrails.org/classes/Rails/Engine.html#label-Isolated+Engine
    isolate_namespace Konacha

    config.konacha = ActiveSupport::OrderedOptions.new

    def self.application(app)
      Rack::Builder.app do
        use Rack::ShowExceptions

        map app.config.assets.prefix do
          run app.assets
        end

        map "/" do
          run Engine
        end
      end
    end

    def self.formatters
      if ENV['FORMAT']
        ENV['FORMAT'].split(',').map do |string|
          eval(string).new(STDOUT)
        end
      else
        [Konacha::Formatter.new(STDOUT)]
      end
    end

    initializer "konacha.environment" do |app|
      options = app.config.konacha

      options.spec_dir     ||= "spec/javascripts"
      options.spec_matcher ||= /_spec\.|_test\./
      options.port         ||= 3500
      options.host         ||= 'localhost'
      options.application  ||= self.class.application(app)
      options.driver       ||= :selenium
      options.stylesheets  ||= %w(application)
      options.javascripts  ||= %w(chai konacha/iframe)
      options.verbose      ||= false
      options.runner_port  ||= nil
      options.formatters   ||= self.class.formatters

      spec_dirs = [options.spec_dir].flatten
      app.config.assets.paths += spec_dirs.map{|d| app.root.join(d).to_s}
      app.config.assets.raise_runtime_errors = false
    end
  end
end
```

Use root namespace for Rails::Engine
user
```ruby
module Konacha
  class Engine < ::Rails::Engine
    # Do not mess up the application's namespace.
    # http://api.rubyonrails.org/classes/Rails/Engine.html#label-Isolated+Engine
    isolate_namespace Konacha

    config.konacha = ActiveSupport::OrderedOptions.new

    def self.application(app)
      Rack::Builder.app do
        use Rack::ShowExceptions

        map app.config.assets.prefix do
          run app.assets
        end

        map "/" do
          run Engine
        end
      end
    end

    def self.formatters
      if ENV['FORMAT']
        ENV['FORMAT'].split(',').map do |string|
          eval(string).new(STDOUT)
        end
      else
        [Konacha::Formatter.new(STDOUT)]
      end
    end

    initializer "konacha.environment" do |app|
      options = app.config.konacha

      options.spec_dir     ||= "spec/javascripts"
      options.spec_matcher ||= /_spec\.|_test\./
      options.port         ||= 3500
      options.host         ||= 'localhost'
      options.application  ||= self.class.application(app)
      options.driver       ||= :selenium
      options.stylesheets  ||= %w(application)
      options.javascripts  ||= %w(chai konacha/iframe)
      options.verbose      ||= false
      options.runner_port  ||= nil
      options.formatters   ||= self.class.formatters

      spec_dirs = [options.spec_dir].flatten
      app.config.assets.paths += spec_dirs.map{|d| app.root.join(d).to_s}
      app.config.assets.raise_runtime_errors = false
    end
  end
end
```
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