使用 go-sqlmock 创建 gorm 数据库（运行时错误）

Question

概括

我正在尝试使用go-sqlmock和gorm进行测试。 我想为初始数据库迁移编写一个测试，但我遇到了一个panic: runtime error: invalid memory address or nil pointer dereference ，我一直无法弄清楚原因。 从错误堆栈来看，我认为是这样的语句： db.AutoMigrate(&models.User{}) 。 我不知道为什么，因为db据称此时已成功启动，并且models.User被定义和实例化为db.AutoMigrate的参数。 我感觉错误出在mocks.NewDatabase函数中，但我不知所措。

不确定是否有人有时间或愿意在相关代码上达到顶峰并帮助我？ 我已经在代码中指出了发生故障的地方（它们在最后两个代码块中）。 如果任何其他上下文会有所帮助，请告诉我。

相关代码

项目/src/models/models.go

package models

import (
    "time"

    "github.com/google/uuid"
    "gorm.io/gorm"
)

type Base struct {
    ID        uuid.UUID      `json:"-" gorm:"primaryKey;type:uuid;not null"`
    CreatedAt time.Time      `json:"-" gorm:"autoCreateTime"`
    UpdatedAt time.Time      `json:"-" gorm:"autoUpdateTime"`
    DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
}

type User struct {
    Base
    Name     string `json:"-"`
    Email    string `json:"-" gorm:"unique_index:user_email_index"`
    Password string `json:"-" gorm:"size:72"`
}

项目/src/mocks/database.go

package mocks

import (
    "project/src/models"
    "log"

    "github.com/DATA-DOG/go-sqlmock"
    "gorm.io/driver/mysql"
    "gorm.io/gorm"
)

func NewDatabase() (*gorm.DB, sqlmock.Sqlmock) {

    // get db and mock
    sqlDB, mock, err := sqlmock.New(
        sqlmock.QueryMatcherOption(sqlmock.QueryMatcherRegexp),
    )
    if err != nil {
        log.Fatalf("[sqlmock new] %s", err)
    }
    defer sqlDB.Close()

    // create dialector
    dialector := mysql.New(mysql.Config{
        Conn: sqlDB,
    DriverName: "mysql",
    })

    // a SELECT VERSION() query will be run when gorm opens the database
    // so we need to expect that here
    columns := []string{"version"}
    mock.ExpectQuery("SELECT VERSION()").WithArgs().WillReturnRows(
    mock.NewRows(columns).FromCSVString("1"),
    )

    // open the database
    db, err := gorm.Open(dialector, &gorm.Config{ PrepareStmt: true })
    if err != nil {
        log.Fatalf("[gorm open] %s", err)
    }

  return db, mock
}

项目/src/数据库/init.go

package database

import (
    "project/src/models"

    "gorm.io/gorm"
)

// Init auto-migrates the DB.
func Init(db *gorm.DB) {
    // Migrate the schema
    // this panics with
    // panic: runtime error: invalid memory address or nil pointer dereference
    // User is defined and instantiated here
    db.AutoMigrate(&models.User{})
}

现在测试：

项目/src/数据库/init_test.go

package database

import (
    "project/src/mocks"
    "testing"
)

func TestInitMigratesDB(t *testing.T) {
    db, mock := mocks.NewDatabase()
    mock.ExpectExec("CREATE TABLE users(.*)")
    mock.ExpectCommit()
    
    // fails here
    Init(db)
}

和日志

Running tool: /usr/local/go/bin/go test -timeout 30s -run ^TestInitMigratesDB$ project/src/database

--- FAIL: TestInitMigratesDB (0.00s)
panic: runtime error: invalid memory address or nil pointer dereference
    panic: runtime error: invalid memory address or nil pointer dereference [recovered]
    panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x11ce22e]

goroutine 35 [running]:
testing.tRunner.func1.2({0x1505320, 0x19bfb00})
    /usr/local/go/src/testing/testing.go:1209 +0x24e
testing.tRunner.func1()
    /usr/local/go/src/testing/testing.go:1212 +0x218
panic({0x1505320, 0x19bfb00})
    /usr/local/go/src/runtime/panic.go:1038 +0x215
database/sql.(*Rows).close(0x0, {0x0, 0x0})
    /usr/local/go/src/database/sql/sql.go:3267 +0x8e
database/sql.(*Rows).Close(0x1e)
    /usr/local/go/src/database/sql/sql.go:3263 +0x1d
panic({0x1505320, 0x19bfb00})
    /usr/local/go/src/runtime/panic.go:1038 +0x215
database/sql.(*Rows).Next(0x0)
    /usr/local/go/src/database/sql/sql.go:2944 +0x27
database/sql.(*Row).Scan(0xc0000afbd8, {0xc0000efb38, 0x11, 0x1})
    /usr/local/go/src/database/sql/sql.go:3333 +0xb4
gorm.io/gorm/migrator.Migrator.CurrentDatabase({{0x0, 0xc000483350, {0x1659c58, 0xc00041a0f0}}})
    /go/pkg/mod/gorm.io/gorm@v1.21.15/migrator/migrator.go:673 +0x8d
gorm.io/gorm/migrator.Migrator.HasTable.func1(0xc0000f8380)
    /go/pkg/mod/gorm.io/gorm@v1.21.15/migrator/migrator.go:265 +0x51
gorm.io/gorm/migrator.Migrator.RunWithValue({{0x80, 0xc000483260, {0x1659c58, 0xc00041a0f0}}}, {0x1512320, 0xc0004fe2a0}, 0xc0000efcb8)
    /go/pkg/mod/gorm.io/gorm@v1.21.15/migrator/migrator.go:50 +0x126
gorm.io/gorm/migrator.Migrator.HasTable({{0x0, 0xc000483260, {0x1659c58, 0xc00041a0f0}}}, {0x1512320, 0xc0004fe2a0})
    /go/pkg/mod/gorm.io/gorm@v1.21.15/migrator/migrator.go:264 +0xe8
gorm.io/gorm/migrator.Migrator.AutoMigrate({{0x0, 0xc000426f90, {0x1659c58, 0xc00041a0f0}}}, {0xc00040f690, 0x0, 0x0})
    /go/pkg/mod/gorm.io/gorm@v1.21.15/migrator/migrator.go:92 +0x127
gorm.io/gorm.(*DB).AutoMigrate(0x151a800, {0xc00040f690, 0x1, 0x1})
    /go/pkg/mod/gorm.io/gorm@v1.21.15/migrator.go:26 +0x43
project/src/database.Init(0xc00041c230)
    /Projects/project/src/database/init.go:12 +0x7b
project/src/database.TestInitMigratesDB(0x0)
    /Projects/project/src/database/init_test.go:12 +0x5a
testing.tRunner(0xc0003a21a0, 0x15b5328)
    /usr/local/go/src/testing/testing.go:1259 +0x102
created by testing.(*T).Run
    /usr/local/go/src/testing/testing.go:1306 +0x35a
FAIL    project/src/database    0.276s
FAIL

Answer 1

弄清楚了。 这是一个配置选项： &gorm.Config{ PrepareStmt: true } 。 虽然这在生产中有效，但它不适用于 sqlmock。 通过将其更改为： &gorm.Config{}来修复它。