我可以使用嵌套接口模拟库代码吗?

Question

我试图在我的 go 代码中的测试中模拟第三方库。但我无法汇编我所采取的方法。有没有办法做到这一点，或者如果我想模拟T2.M2的结果，我可以采取另一种方法？

package main
import (
"fmt"
)
// Two types in a library that I dont have control over
type T1 struct {}
func (T1) M1() T2 {
return T2{}
}
type T2 struct {}
func (T2) M2() {
fmt.Println("hello world")
}
// I created these interfaces in order to assign an instance of T1 
// to a variable of type I1 so that I can mock the behavior of T2.M2()
// problem is that this doesn't compile.
type I1 interface {
M1() I2
}
type I2 interface {
M2() // I want to mock this method
}
// Then I would be able to create a mock
type Mock1 struct {}
func (Mock1) M1() I2 {
return Mock2{}
}
type Mock2 struct {}
func (Mock2) M2() {
fmt.Println("HELLO WORLD")
}
func main() {
var i1 I1
i1 = T1{}
i1.M1().M2()
i1 = Mock1{}
i1.M1().M2()
}

https://play.golang.org/p/sv-Uuuke1dr

Answer 1

将依赖项包装在嵌入依赖类型的结构中：

// answer wrap your dependency
type Ta1 struct {
T1
}
func (Ta1) M1() I2 {
return Ta2{}
}
type Ta2 struct {
T2
}

然后它将起作用：

func main() {
var i1 I1
i1 = Ta1{}
i1.M1().M2()
i1 = Mock1{}
i1.M1().M2()
}

试穿 https://play.golang.org/p/aHr78dY_c9a

Answer 2

你不能在 Go 中模拟结构。只有接口。