gistfile1.builder

def assert_monthly_apr_payment_matches(loan_amount, rate, period, fee, points)
  mortgage_util = MortgageUtil.new(loan_amount, rate, period, fee, points)
  monthly_payment_with_fees = mortgage_util.monthly_payment_with_fees
  monthly_payment_from_apr = MortgageUtil.new(loan_amount, mortgage_util.apr, period, 0, 0).monthly_payment
  monthly_payment_with_fees.should be_close(monthly_payment_from_apr, 0.01)
end

it "should calculate original monthly payment from APR" do
  assert_monthly_apr_payment_matches(300000, 6.5, 360, 1200, 1.25)
  assert_monthly_apr_payment_matches(300000, 6.5, 360, 0, 0)
  assert_monthly_apr_payment_matches(400000, 1.1, 180, 1200, 1.25)
  assert_monthly_apr_payment_matches(300000, 6.5, 360, 0, 7.25)
  assert_monthly_apr_payment_matches(300000, 6.5, 360, 10000, 7.25)
end