note testing.M.Cleanup was previously declined in #42161

note testing.M.Cleanup was previously declined in #42161

Thanks for the reference. I think there is another valid use case here which I didn't see in that proposal. Also, we can achieve TestMain timing without these as I suggested.

note testing.M.Cleanup was previously declined in #42161

I believe this was erroneously declined, on the basis that:

It seems to me that testing.M.Cleanup can be implemented simply using defer.

This is not true. Consider:

package test

import (
	"fmt"
	"os"
	"testing"
)

func TestMain(m *testing.M) {
	defer func() {
		fmt.Println("cleanup code")
	}()
	os.Exit(m.Run())
}

func TestFoo(t *testing.T) {
	t.Fatalf("oh no")
}

Cleanup code does not execute because of os.Exit(), which is called because the docs tell you to:

Run runs the tests. It returns an exit code to pass to os.Exit.

Let's ignore that for now then. Consider this other code:

package test

import (
	"fmt"
	"testing"
)

func TestMain(m *testing.M) {
	defer func() {
		fmt.Println("cleanup code")
	}()
	m.Run()
}

func TestFoo(t *testing.T) {
	panic("oh no")
}

In this scenario, the defer does not run at all.

It's simply not true that you can get cleanup functions working at the testing.M level with the current tooling.

It's simply not true that you can get cleanup functions working at the testing.M level with the current tooling.

@kegsay argument is true. I experienced the same behavior. Any progress on this feature or any alternatives on working around this scenario?