```ruby
require 'sinatra'

class App < Sinatra::Base
  get('/v1/success') do
    status 200
  end

  post('/v1/forbidden') do
    status 403
  end

  get('/v1/not_found') do
    status 404
  end

  post('/v1/service_unavailable')  do
    status 503
  end
end

run App```

Add body check route to spec test rackup
user
```ruby
require 'sinatra'

class App < Sinatra::Base
  get('/v1/success') do
    status 200
  end

  post('/v1/forbidden') do
    status 403
  end

  get('/v1/not_found') do
    status 404
  end

  post('/v1/service_unavailable')  do
    status 503
  end

  post('/v1/retry_body') do
    body = request.env["rack.input"].read
    if body.empty?
      status 504 # body not sent
    else
      status 502 # body sent
    end
  end
end

run App```
assistant