Add before block
Add 'instanciates receiving a ShippingProvider class' test
Add 'has a get_fee method that returns a hash with :provider, :origin :destination and :fees keys' test
Create ShiṕpingFee class
Create constructor
Fix has_key? method name
Add 'get_fee' method
Add 'shows provider name' test
Add attr_reader :provider
Add 'shows form URL0 test
Add URL and FORM_URL constants and remove their attr_reader
Add PROVIDER constant and remove its attr_reader