Using Rack gem in Rails

Using Rack gem in Rails

I'm trying to use a stupid little Rack gem I just wrote in my Rails
project, but I keep on getting an uninitialized constant error whenever I
call it. This is driving me insane because I've already written Rack gems
before, and those work in my Rails projects just fine.
In my Gemfile:
gem 'hide_heroku', :git => 'https://github.com/ykessler/hide-heroku'
In my application.rb:
module Tester
class Application < Rails::Application
config.middleware.use Rack::HideHeroku
But starting my local server, I get:
uninitialized constant Rack::HideHeroku (NameError)
The gem:
module Rack
class HideHeroku
def initialize(app)
@app=app
end
def call(env)
@status, @headers, @response = @app.call(env)
@request = Rack::Request.new(env)
[@status, _apply_headers, @response]
end
private
def _apply_headers
if /\.herokuapp\.com\/?.*/ =~ @request.url
@headers['X-Robots-Tag'] = 'noindex, nofollow'
end
@headers
end
end
end
See it here: https://github.com/appgrinders/rack-conditional-response-headers