本篇内容介绍了“Golang如何实现单元测试中的逻辑层”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！

准备工作

安装

go install github.com/golang/mock/mockgen@v1.6.0

基本 case 代码

首先我们还是基于上一次的例子，这里给出上一次例子中所用到的接口

package service

import (
    "context"
    "fmt"

    "go-demo/m/unit-test/entity"
)

type UserRepo interface {
    AddUser(ctx context.Context, user *entity.User) (err error)
    DelUser(ctx context.Context, userID int) (err error)
    GetUser(ctx context.Context, userID int) (user *entity.User, exist bool, err error)
}

type UserService struct {
    userRepo UserRepo
}

func NewUserService(userRepo UserRepo) *UserService {
    return &UserService{userRepo: userRepo}
}

func (us *UserService) AddUser(ctx context.Context, username string) (err error) {
    if len(username) == 0 {
        return fmt.Errorf("username not specified")
    }
    return us.userRepo.AddUser(ctx, &entity.User{Username: username})
}

func (us *UserService) GetUser(ctx context.Context, userID int) (user *entity.User, err error) {
    userInfo, exist, err := us.userRepo.GetUser(ctx, userID)
    if err != nil {
        return nil, err
    }
    if !exist {
        return nil, fmt.Errorf("user %d not found", userID)
    }
    return userInfo, nil
}

可以看到我们的目标很明确，就是需要 mock 掉

UserRepo

AddUser

GetUser

生成 mock 接口

使用

mockgen

mockgen -source=./service/user.go -destination=./mock/user_mock.go -package=mock

参数名称都很好理解，我这边不赘述了。命令执行完成之后，会在

destination

生成的代码大致如下面的样子，可以简单瞄一眼：

// Code generated by MockGen. DO NOT EDIT.
// Source: ./user.go

// Package mock is a generated GoMock package.
package mock

import (
    context "context"
    entity "go-demo/m/unit-test/entity"
    reflect "reflect"

    gomock "github.com/golang/mock/gomock"
)

// MockUserRepo is a mock of UserRepo interface.
type MockUserRepo struct {
    ctrl     *gomock.Controller
    recorder *MockUserRepoMockRecorder
}

// MockUserRepoMockRecorder is the mock recorder for MockUserRepo.
type MockUserRepoMockRecorder struct {
    mock *MockUserRepo
}

// NewMockUserRepo creates a new mock instance.
func NewMockUserRepo(ctrl *gomock.Controller) *MockUserRepo {
    mock := &MockUserRepo{ctrl: ctrl}
    mock.recorder = &MockUserRepoMockRecorder{mock}
    return mock
}

// EXPECT returns an object that allows the caller to indicate expected use.
func (m *MockUserRepo) EXPECT() *MockUserRepoMockRecorder {
    return m.recorder
}

// AddUser mocks base method.
func (m *MockUserRepo) AddUser(ctx context.Context, user *entity.User) error {
    m.ctrl.T.Helper()
    ret := m.ctrl.Call(m, "AddUser", ctx, user)
    ret0, _ := ret[0].(error)
    return ret0
}

// AddUser indicates an expected call of AddUser.
func (mr *MockUserRepoMockRecorder) AddUser(ctx, user interface{}) *gomock.Call {
    mr.mock.ctrl.T.Helper()
    return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "AddUser", reflect.TypeOf((*MockUserRepo)(nil).AddUser), ctx, user)
}

// DelUser mocks base method.
func (m *MockUserRepo) DelUser(ctx context.Context, userID int) error {
    m.ctrl.T.Helper()
    ret := m.ctrl.Call(m, "DelUser", ctx, userID)
    ret0, _ := ret[0].(error)
    return ret0
}

// DelUser indicates an expected call of DelUser.
func (mr *MockUserRepoMockRecorder) DelUser(ctx, userID interface{}) *gomock.Call {
    mr.mock.ctrl.T.Helper()
    return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "DelUser", reflect.TypeOf((*MockUserRepo)(nil).DelUser), ctx, userID)
}

// GetUser mocks base method.
func (m *MockUserRepo) GetUser(ctx context.Context, userID int) (*entity.User, bool, error) {
    m.ctrl.T.Helper()
    ret := m.ctrl.Call(m, "GetUser", ctx, userID)
    ret0, _ := ret[0].(*entity.User)
    ret1, _ := ret[1].(bool)
    ret2, _ := ret[2].(error)
    return ret0, ret1, ret2
}

// GetUser indicates an expected call of GetUser.
func (mr *MockUserRepoMockRecorder) GetUser(ctx, userID interface{}) *gomock.Call {
    mr.mock.ctrl.T.Helper()
    return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetUser", reflect.TypeOf((*MockUserRepo)(nil).GetUser), ctx, userID)
}

编写单元测试

gomock

EXPECT()

package service

import (
    "context"
    "testing"

    "github.com/golang/mock/gomock"
    "github.com/stretchr/testify/assert"
    "go-demo/m/unit-test/entity"
    "go-demo/m/unit-test/mock"
)

func TestUserService_AddUser(t *testing.T) {
    ctl := gomock.NewController(t)
    defer ctl.Finish()

    mockUserRepo := mock.NewMockUserRepo(ctl)
    userInfo := &entity.User{Username: "LinkinStar"}
    // 无论对 AddUser 方法输入任意参数，均会返回 userInfo 信息
    mockUserRepo.EXPECT().AddUser(gomock.Any(), gomock.Any()).Return(nil)

    userService := NewUserService(mockUserRepo)
    err := userService.AddUser(context.TODO(), userInfo.Username)
    assert.NoError(t, err)
}

func TestUserService_GetUser(t *testing.T) {
    ctl := gomock.NewController(t)
    defer ctl.Finish()

    userID := 1
    username := "LinkinStar"

    mockUserRepo := mock.NewMockUserRepo(ctl)
    // 只有当对于 GetUser 传入 userID 为 1 时才会返回 user 信息
    mockUserRepo.EXPECT().GetUser(context.TODO(), userID).Return(&entity.User{
        ID:       userID,
        Username: username,
    }, true, nil)

    userService := NewUserService(mockUserRepo)
    userInfo, err := userService.GetUser(context.TODO(), userID)
    assert.NoError(t, err)
    assert.Equal(t, username, userInfo.Username)
}

与之前一样，我们依旧使用

github.com/stretchr/testify

优化

当然，如果我们每次修改接口或者新增接口都需要重新执行一次命令，一个文件还好，当有很多文件的时候肯定是非常困难的。所以我们需要使用 go:generate 来优化一下。

我们可以在需要 mock 的接口上方加入注释(注意这里写的路径要和实际路径相符合)：

//go:generate mockgen -source=./user.go -destination=../mock/user_mock.go -package=mock
type UserRepo interface {
    AddUser(ctx context.Context, user *entity.User) (err error)
    DelUser(ctx context.Context, userID int) (err error)
    GetUser(ctx context.Context, userID int) (user *entity.User, exist bool, err error)
}

然后只需要使用命令

go generate ./...

就可以生成全部的 mock 嘞，所以及时文件很多，只需要利用好 go:generate 也能一次搞定。