http://square.jobs/

payment.rb

# Usage: spec payment.rb
# Depends on Ruby and Rspec.
#
# Modify this code to compute the correct fee amount for a given payment amount.
# Add additional tests to cover any behavior you introduce.

class Payment
  BASIS_POINTS = 290
  INTERCHANGE  = 15

  def initialize(amount)
    @amount = amount
  end
end

describe Payment, "#fee_amount is calculated from the basis points and the interchange fee" do
  it "returns 44 cents for $10.00" do
    payment = Payment.new(10.00)
    payment.fee_amount.should == 0.44
  end
end