如何在没有接口的 Go 测试用例中模拟结构体方法？

type A struct {}

func (a *A) perfom(string){
...
...
..
}

type Performer interface {
    perform(string)
}

type AMock struct {}

func (a *AMock) perform(string) {
    // Mocked behavior
}

type A struct {}

func (a *A) perform(string) {
    // Real implementation
}

func invoke(url string, p Performer) {
    out := p.perfom(url)
    ...
    ...
}

func TestInvokeWithMock(t *testing.T) {
    var amok = &AMock{}
    invoke("url", amok)
    // Verify mock behavior (e.g., assert it was called with the correct argument)
}

func TestInvokeWithReal(t *testing.T) {
    var a = &A{}
    invoke("url", a)
    // No need for verification since it's the real implementation
}