Exploring CleanupOnInterrupt: go run main.go and ctrl-C after it says sleeping. You should see both cleanup functions.

main.go

package main

import (
	"fmt"
	"time"

	pkgtest "knative.dev/pkg/test"
)

func main() {
	pkgtest.CleanupOnInterrupt(func() {
		fmt.Println("I am cleanup function 1")
	}, nil)

	pkgtest.CleanupOnInterrupt(func() {
		fmt.Println("I am cleanup function 2")
	}, nil)
	doSomeStuff()

  fmt.Println("sleeping, interrupt me")
	time.Sleep(30 * time.Second)
	fmt.Println("awake")

}

func doSomeStuff() {
	fmt.Println("doing stuff")
	pkgtest.CleanupOnInterrupt(func() {
		fmt.Println("I am cleanup function 3")
	}, nil)

}