factory.go
// factory
package factory
import (
"errors"
"fmt"
)
const (
Cash = 1
DebitCard = 2
)
type PaymentMethod interface {
Pay(amount float32) string
}
func GetPaymentMethod(m int) (PaymentMethod, error) {
switch m {
case Cash:
return new(CashPM), nil
case DebitCard:
return new(DebitCardPM), nil
default:
return nil, errors.New(fmt.Sprintf("Payment method %d not recognized!", m))
}
}
type CashPM struct{}
type DebitCardPM struct{}
func (c *CashPM) Pay(amount float32) string {
return fmt.Sprintf("%0.2f paid using cash", amount)
}
func (c *DebitCardPM) Pay(amount float32) string {
return fmt.Sprintf("%#0.2f paid using debit card", amount)
}
factory_test.go
// factorymethod
package factory
import (
"strings"
"testing"
)
func TestGetPaymentMethodCash(t *testing.T) {
payment, err := GetPaymentMethod(Cash)
if err != nil {
t.Fatal("A payment method of type 'Cash' must exist")
}
msg := payment.Pay(10.30)
if !strings.Contains(msg, "paid using cash") {
t.Error("The cash payment method message doesn't correct")
}
t.Log("Log:", msg)
}
func TestGetPaymentMethodDebitCard(t *testing.T) {
payment, err := GetPaymentMethod(DebitCard)
if err != nil {
t.Fatal("A payment method of type 'DebitCard' must exist")
}
msg := payment.Pay(22.30)
if !strings.Contains(msg, "paid using debit card") {
t.Error("The debit card payment method message doesn't correct")
}
t.Log("Log:", msg)
}
程序输出如下,
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