删除fmt.Println（）时，golang中的猴子修补失败

Question

While writing a test I have to patch a method in order to check that it is called, this is my code:

import "fmt"

type myStruct struct {}

func (myObject *myStruct) firstMethod() {
    myObject.SecondMethod()
}
func (myObject *myStruct) SecondMethod() {
    fmt.Println("Inside the original SecondMethod") //test fails if I remove this
}

and this is the test:

import (
    "reflect"
    "testing"
    "github.com/bouk/monkey"
    "github.com/stretchr/testify/assert"
    "fmt"
)
func TestThatSecondMethodIsCalled(t *testing.T) {
    myObject := &myStruct{}

    wasCalled := false
    monkey.PatchInstanceMethod(
        reflect.TypeOf(myObject),
        "SecondMethod",
        func(*myStruct) {
            fmt.Println("Inside the replacement of SecondMethod")
            wasCalled = true
        },
    )

    myObject.firstMethod()
    assert.True(t, wasCalled)
}

If I run the test like this, it will pass, but if I remove the fmt.Println() from SecondMethod, then the test fails (the test uses the original body of the method, not the patched one).

Also if I use debugging from Goland, the test passes even if SecondMethod has an empty body.

Answer 1

This is caused by compiler's inline optimize, add -gcflags="-N -I" will disable it.