If a struct field is a channel and it might change (say, for a stub/mock in tests?), careful how you "range" over it

for-channel-demo.go

package main

import "log"

type ForTest struct {
	ch chan int
}

func main() {
	thing := &ForTest{ch: make(chan int)}

	// this works...
	go func() {
		for {
			b := <-thing.ch
			log.Println("got", b)
		}
	}()

	// ... whereas this will deadlock
	// go func() {
	// 	for b := range thing.ch {
	// 		log.Println("got", b)
	// 	}
	// }()

	thing.ch <- 1
	thing.ch = make(chan int)
	thing.ch <- 2
}