Fakes in Ruby

fake.rb

class FileTransferJob
  def initialize(ftp_service = FtpService.new)
    @ftp_service = ftp_service
  end
  
  def do_the_needful
    @ftp_service.put("/tmp/the_file_to_send", "/tmp/the_destination")
  end
end

describe FileTransferJob do
  class FakeFtpService
    attr_accessor :transfers

    def put(file, destination)
      self.transfers ||= []
      transfers << {:file => file, :destination => destination}
    end
  end
  
  let(:ftp_service) { FakeFtpService.new }
  let(:job) { FileTransferJob.new(ftp_service) }
  
  it "sends the file" do
    job.do_the_needful
    
    ftp_service.transfers.first[:file].should == "/tmp/the_file_to_send"
    ftp_service.transfers.first[:destination].should == "/tmp/the_destination"
  end
end

gistfile1.sh

Matthews-MacBook-Air:lobot (ubuntu) $ rspec ~/Desktop/fake.rb 

FileTransferJob
  sends the file

Finished in 0.00058 seconds
1 example, 0 failures