如何在Golang中建立模拟类？

I'm trying to build mock class for unit test in golang; does anyone know how to do that? For example, in the following code slice, I'd like to print FakeMyClass.Object's return value.

package main

import (
    "fmt"
)

type MyClass struct {
}

func (*MyClass) Object() (int) {
    return 0
}

func (mc *MyClass) PrintInfo() {
    fmt.Printf("%v
", mc.Object())
}

type FakeMyClass struct {
    MyClass
}

func (*FakeMyClass) Object() (int) {
    return 1
}

func main() {
    mc := &FakeMyClass{}
    mc.PrintInfo()
}

I prefer to use github.com/stretchr/testify/tree/master/mock

package main

import (
    "fmt"
    "github.com/stretchr/testify/mock"
)

type MyClass struct {
}

func (*MyClass) Object() (int) {
    return 0
}

func (mc *MyClass) PrintInfo() {
    fmt.Printf("%v
", mc.Object())
}

type FakeMyClass struct {
    mock.Mock
}

func (fmc *FakeMyClass) Object() (int) {
    args := fmc.Called()
    return args.Int(0)
}
func (fmc *FakeMyClass) PrintInfo() {
    fmt.Printf("%v
", fmc.Object())
}

func main() {
    mc := &FakeMyClass{}
    mc.On("Object").Return(1)
    mc.PrintInfo()
    //mc.AssertExpectations(t)
}

You can make a struct that returns mocked functions, which you pass in with each test case for values you want returned. For example:

package main

import (
    "fmt"
)

type MyClass struct{}

func (*MyClass) Object() int {
    return 0
}
func (mc *MyClass) PrintInfo() {
    fmt.Printf("%v
", mc.Object())
}

type FakeMyClass struct {
     ObjectMock: func() int
}

func (fm *FakeMyClass) Object() int {
    return fm.ObjectMock()
}
func (fm *FakeMyClass) PrintInfo() {
    fmt.Printf("%v
", fm.Object())
}

func main() {

    mc := &FakeMyClass{
        // Create the mocked function here, to be called when the Object() function is called.
        ObjectMock: func() int {
            return 0
        }
    }

    mc.PrintInfo()
}

You are looking for virtual dispatch on the Object() method. The only form of virtual dispatch that I know of in Go is to use interfaces.

PrintInfo will then be a function that uses that interface type.

E.g.:

package main

import (
    "fmt"
)

type WithObject interface {
    Object() int
}

func PrintInfo(wo WithObject) {
    fmt.Printf("%v
", wo.Object())
}

type MyClass struct {
}

func (*MyClass) Object() (int) {
    return 0
}

type FakeMyClass struct {
    MyClass
}

func (*FakeMyClass) Object() (int) {
    return 1
}

func main() {
    fmc := &FakeMyClass{}
    PrintInfo(fmc)
}

I used mockgen for it:

mockgen -source myModule.go -package myPackage -destination myModuleMock.go

You can install it by: got get github.com/golang/mock