golang mock

main.go

package main

type base struct{}

type service struct {
	sub *service
}

func (*service) create() (bool, error) {
	return true, nil
}
func main() {
	c := &csr{}
	c.step1()
	c.step2()
}

func newSerivce() *service {
	return &service{}
}

type csr struct {
	s *service
}

func (c *csr) step1() {
	c.s = newSerivce()

}

func (c *csr) step2() error {
	r, err := c.s.sub.sub.sub.sub.create()
	if err != nil {
		return err
	}
	println(r)
	return nil
}

main2.go

package main

type base struct{}

type service struct {
	sub *service
}

func (*service) create() (bool, error) {
	return true, nil
}
func main() {
	c := &csr{&defaultServicer{}}
	c.step1()
	c.step2()
}

func newSerivce() *service {
	return &service{}
}

type csrServicer interface {
	init() error
	create() (bool, error)
}

type defaultServicer struct {
	s *service
}

func (d *defaultServicer) init() error {
	d.s = newSerivce()
	return nil
}

func (d *defaultServicer) create() (bool, error) {
	return d.s.sub.sub.sub.sub.create()
}

type csr struct {
	s csrServicer
}

func (c *csr) step1() {
	c.s.init()
}

func (c *csr) step2() error {
	r, err := c.s.create()
	if err != nil {
		return err
	}
	println(r)
	return nil
}

main_test.go

package main

import "errors"

func test() {
	c := &csr{&defaultServicer{}}
	c.step1()
	c.step2()
}

type mockServicer struct {
}

func (d *mockServicer) init() error {
	return nil
}

func (d *mockServicer) create() (bool, error) {
	return false, errors.New("")
}

func test2() {
	c := &csr{&mockServicer{}}
	c.step1()
	c.step2()
}