Go项目中使用mockgen提升单元测试效率的实践指南

GO111MODULE=on go get github.com/golang/mock/mockgen@v1.6.0

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

// user_repository.go
type UserRepository interface {
    GetUser(id int64) (*User, error)
}

# 源码模式（推荐）
mockgen -source=./user_repository.go -destination=./mocks/mock_user_repo.go -package=mocks

# 反射模式（无源码时）
mockgen -destination=./mocks/mock_user_repo.go -package=mocks your_module/user_repository UserRepository

func TestGetUser(t *testing.T) {
    ctrl := gomock.NewController(t)
    defer ctrl.Finish() // Go≥1.14可省略

    // 创建UserRepository的Mock对象
    mockRepo := mocks.NewMockUserRepository(ctrl)
    
    // 预设行为：当传入id=1时返回模拟用户
    mockRepo.EXPECT().
        GetUser(gomock.Eq(int64(1))). // 参数匹配
        Return(&User{ID: 1, Name: "Alice"}, nil). // 返回值
        Times(1) // 预期调用次数

    // 注入Mock对象
    service := NewUserService(mockRepo)
    user, err := service.GetUser(1)
    
    // 断言结果
    assert.NoError(t, err)
    assert.Equal(t, "Alice", user.Name)
}

mockRepo.EXPECT().GetUser(gomock.Any()).Return(nil, errors.New("not found")) // 匹配任意参数

mockRepo.EXPECT().GetUser(gomock.Any()).
    DoAndReturn(func(id int64) (*User, error) {
        if id == 1 {
            return &User{Name: "Alice"}, nil
        }
        return nil, errors.New("not found")
    })

gomock.InOrder(
    mockRepo.EXPECT().GetUser(1).Return(user1, nil),
    mockRepo.EXPECT().GetUser(2).Return(user2, nil),
)

//go:generate mockgen -destination=./mocks/mock_user_repo.go -package=mocks your_module/user_repository UserRepository

# GitHub Actions示例
jobs:
  test:
    steps:
      - run: go generate ./...
      - run: go test -coverprofile=coverage.out ./...

tests := []struct {
    name string
    id   int64
    want *User
}{
    {"valid", 1, &User{Name: "Alice"}},
    {"invalid", 2, nil},
}
for _, tt := range tests {
    t.Run(tt.name, func(t *testing.T) {
        // 配置Mock并调用被测方法
    })
}