pointer go

test.go

// LOOP DE TESTE
for _, tc := range testCases {
  t.Run(tc.testName, func(t *testing.T) {
    record := Call{
      StartPeriod: tc.start,
      EndPeriod:   tc.end,
    }

    price, _ := CalcAmount(record)
    amountAsDecimal, _ := decimal.NewFromFloat(tc.expectedAmount).Float64()
    billingAmount, _ := price.Float64()

    if billingAmount != amountAsDecimal {
      t.Errorf(errorMessage, tc.testName, amountAsDecimal, billingAmount)
    }
  })
}

// METEDO QUE REALIZA O CALCULO
func CalcAmount(c Call) (decimal.Decimal, error) {
  decimal.DivisionPrecision = 2
  diff, err := c.Duration()
  if err != nil {
    return decimal.Zero, err
  }

  var amount decimal.Decimal
  if !c.InReducedTariffPeriod() {
    exactMinutes := math.Floor(diff.Minutes())
    amount = amount.Add(
      decimal.NewFromFloat(exactMinutes).Mul(minuteFee),
    )
  }

  amount = amount.Add(connectionFee)

  return amount, nil
}

func (c *Call) Duration() (time.Duration, error) {
	if c.StartPeriod.IsZero() || c.EndPeriod.IsZero() {
		return 0, errInvalidCallPeriod
	}

	// if the call is not in reduced period the fee per minute
	// should be calc only until 22:00
	if !c.InReducedTariffPeriod() {
		h, m, s, ns := 22, 00, 00, 00
		c.EndPeriod = time.Date(
			c.StartPeriod.Year(), c.StartPeriod.Month(), c.StartPeriod.Day(),
			h, m, s, ns, time.UTC,
		)
	}

	return c.EndPeriod.Sub(c.StartPeriod), nil
}

//{
//	testName:       "2 minutes of call",
//	start:          time.Date(2019, 9, 21, 21, 57, 13, 0, time.UTC),
//	end:            time.Date(2019, 9, 22, 10, 11, 10, 0, time.UTC),
//	expectedAmount: 0.54,
//},
//{
//	testName:       "1 minute of call",
//	start:          time.Date(2019, 9, 21, 10, 10, 10, 0, time.UTC),
//	end:            time.Date(2019, 9, 21, 10, 11, 10, 0, time.UTC),
//	expectedAmount: 0.45,
//},