[Go] 使用 go-sqlmock 模拟数据库驱动编写单元测试用例

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go get github.com/DATA-DOG/go-sqlmock

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package main

import (
	"database/sql"

	_ "github.com/go-sql-driver/mysql"
)

func recordStats(db *sql.DB, userID, productID int64) (err error) {
	tx, err := db.Begin()
	if err != nil {
		return
	}

	defer func() {
		switch err {
		case nil:
			err = tx.Commit()
		default:
			tx.Rollback()
		}
	}()

	if _, err = tx.Exec("UPDATE products SET views = views + 1"); err != nil {
		return
	}
	if _, err = tx.Exec("INSERT INTO product_viewers (user_id, product_id) VALUES (?, ?)", userID, productID); err != nil {
		return
	}
	return
}

func main() {
	// @NOTE: the real connection is not required for tests
	db, err := sql.Open("mysql", "root@/blog")
	if err != nil {
		panic(err)
	}
	defer db.Close()

	if err = recordStats(db, 1 /*some user id*/, 5 /*some product id*/); err != nil {
		panic(err)
	}
}

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package main

import (
	"fmt"
	"testing"

	"github.com/DATA-DOG/go-sqlmock"
)

// go test -mod=mod -v -run="TestShouldUpdateStats"
// a successful case
func TestShouldUpdateStats(t *testing.T) {
	db, mock, err := sqlmock.New()
	if err != nil {
		t.Fatalf("an error '%s' was not expected when opening a stub database connection", err)
	}
	defer db.Close()

	mock.ExpectBegin()
	mock.ExpectExec("UPDATE products").WillReturnResult(sqlmock.NewResult(1, 1))
	mock.ExpectExec("INSERT INTO product_viewers").WithArgs(2, 3).WillReturnResult(sqlmock.NewResult(1, 1))
	mock.ExpectCommit()

	// now we execute our method
	if err = recordStats(db, 2, 3); err != nil {
		t.Errorf("error was not expected while updating stats: %s", err)
	}

	// we make sure that all expectations were met
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Errorf("there were unfulfilled expectations: %s", err)
	}
}

// a failing test case
func TestShouldRollbackStatUpdatesOnFailure(t *testing.T) {
	db, mock, err := sqlmock.New()
	if err != nil {
		t.Fatalf("an error '%s' was not expected when opening a stub database connection", err)
	}
	defer db.Close()

	mock.ExpectBegin()
	mock.ExpectExec("UPDATE products").WillReturnResult(sqlmock.NewResult(1, 1))
	mock.ExpectExec("INSERT INTO product_viewers").
		WithArgs(2, 3).
		WillReturnError(fmt.Errorf("some error"))
	mock.ExpectRollback()

	// now we execute our method
	if err = recordStats(db, 2, 3); err == nil {
		t.Errorf("was expecting an error, but there was none")
	}

	// we make sure that all expectations were met
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Errorf("there were unfulfilled expectations: %s", err)
	}
}

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> go test -mod=mod -v -run="TestShouldUpdateStats"
go: finding module for package github.com/DATA-DOG/go-sqlmock
go: finding module for package github.com/go-sql-driver/mysql
go: downloading github.com/go-sql-driver/mysql v1.6.0
go: downloading github.com/DATA-DOG/go-sqlmock v1.5.0
go: found github.com/go-sql-driver/mysql in github.com/go-sql-driver/mysql v1.6.0
go: found github.com/DATA-DOG/go-sqlmock in github.com/DATA-DOG/go-sqlmock v1.5.0
=== RUN   TestShouldUpdateStats
--- PASS: TestShouldUpdateStats (0.00s)
PASS
ok      tools/sqlmock   0.016s

> go test -mod=mod -v -run="TestShouldRollbackStatUpdatesOnFailure"
=== RUN   TestShouldRollbackStatUpdatesOnFailure
--- PASS: TestShouldRollbackStatUpdatesOnFailure (0.00s)
PASS
ok      tools/sqlmock   0.014s

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package main

import (
	"time"

	"gorm.io/driver/mysql"
	"gorm.io/gorm"
)

type Product struct {
	ID        uint `gorm:"primarykey"`
	CreatedAt time.Time
	UpdatedAt time.Time
	Code      string
	Price     uint
}

type Repository struct {
	db *gorm.DB
}

func (p *Repository) ListAll() ([]*Product, error) {
	var l []*Product
	err := p.db.Find(&l).Error
	return l, err
}

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func getDBMock() (*gorm.DB, sqlmock.Sqlmock, error) {
	// mock一个*sql.DB对象，不需要连接真实的数据库
	db, mock, err := sqlmock.New(sqlmock.QueryMatcherOption(sqlmock.QueryMatcherEqual))
	if err != nil {
		return nil, nil, err
	}

	//测试时不需要真正连接数据库
	gormDB, err := gorm.Open(mysql.New(mysql.Config{
		Conn:                      db,
		SkipInitializeWithVersion: true,
	}), &gorm.Config{})
	if err != nil {
		return nil, nil, err
	}

	return gormDB, mock, nil
}

func Test_GormListAll(t *testing.T) {
	db, mock, err := getDBMock()
	if err != nil {
		t.Fatalf("an error '%s' was not expected when opening a stub database connection", err)
	}

	repository := &Repository{db: db}

	const sqlSelectAll = "SELECT * FROM `products`"

	mock.ExpectQuery(sqlSelectAll).
		WillReturnRows(sqlmock.NewRows(nil))

	l, err := repository.ListAll()
	if err != nil {
		t.Fatal(err)
	}
	t.Logf("%#v", l) // []*main.Product{}
}

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> go test -mod=mod -v -run="Test_GormListAll"
=== RUN   Test_GormListAll
    gorm_test.go:51: []*main.Product{}
--- PASS: Test_GormListAll (0.00s)
PASS