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[Go] Factory Pattern(팩토리 패턴) 구현

상쾌한기분 2022. 7. 25. 12:16
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Factory Pattern

운송업체별로 물리 프린터기 출력용지나 출력물 등 달라지는데 여기서는 물리 프린터기에서 출력을 위한 데이터를
팩토리 패턴으로 구현 하였다.

  1. PrineterMethod Interface 구현
  2. EMSPrinter, SFPrinter struct 구현 → GetOuput() 구현
  3. Create() 를 통해서 new() 로 사용할 Prineter를 Create and Return
  4. Return Struct의 GetOuput() 메소드를 통해 결과값 Return

factory.go

package factory

import (
    "errors"
    "fmt"
)

const (
    EMS_CODE = "EMS"
    SF_CODE  = "SF"
)

type PrinterMethod interface {
    GetOutput(code string) string
}

type EMSPrinter struct{}
type SFPrinter struct{}

func (p *EMSPrinter) GetOutput(packageCode string) string {
    return fmt.Sprintf("<html><body><img src=\"http://host.com/%s.png\"></body></html>", packageCode)
}

func (p *SFPrinter) GetOutput(packageCode string) string {
    return fmt.Sprintf("^BZ^X,Y,100,100,%s^BI^BZ", packageCode)
}

func CreatePrinterMethod(transferCompanyCode string) (PrinterMethod, error) {
    switch transferCompanyCode {
    case EMS_CODE:
        return new(EMSPrinter), nil
    case SF_CODE:
        return new(SFPrinter), nil
    default:
        return nil, errors.New(fmt.Sprintf("%s is not implemented", transferCompanyCode))
    }
}

factory_test.go

package factory_test

import (
    "testing"

    "github.com/go-playground/assert/v2"
    "github.com/sanggi-wjg/go_demos/sample/pattern/factory"
)

func TestCreate(t *testing.T) {
    // given
    transferCompanyCode1 := factory.EMS_CODE
    transferCompanyCode2 := factory.SF_CODE
    transferCompanyCode3 := "What"

    // when
    method1, err1 := factory.CreatePrinterMethod(transferCompanyCode1)
    method2, err2 := factory.CreatePrinterMethod(transferCompanyCode2)
    method3, err3 := factory.CreatePrinterMethod(transferCompanyCode3)

    // then
    assert.Equal(t, method1, factory.EMSPrinter{})
    assert.Equal(t, err1, nil)

    assert.Equal(t, method2, factory.SFPrinter{})
    assert.Equal(t, err2, nil)

    assert.Equal(t, method3, nil)
    assert.NotEqual(t, err3, nil)
}

func TestCreateEMS(t *testing.T) {
    // given
    packageCode := "123"
    transferCompanyCode := factory.EMS_CODE

    // when
    printerMethod, err := factory.CreatePrinterMethod(transferCompanyCode)
    output := printerMethod.GetOutput(packageCode)

    // then
    assert.Equal(t, err, nil)
    assert.Equal(t, output, "<html><body><img src=\"http://host.com/123.png\"></body></html>")
}

func TestCreateSF(t *testing.T) {
    // given
    packageCode := "123"
    transferCompanyCode := factory.SF_CODE

    // when
    printerMethod, err := factory.CreatePrinterMethod(transferCompanyCode)
    output := printerMethod.GetOutput(packageCode)

    // then
    assert.Equal(t, err, nil)
    assert.Equal(t, output, "^BZ^X,Y,100,100,123^BI^BZ")
}
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