Check if a Go Channel is open or closed

channel_check.go

// An intersting pattern for testing, but you can use the check anywhere
import "testing"

func TestCheckingChannel(t *testing.T) {
  stop := make(chan bool)

  // Testing some fucntion that SHOULD close the channel
  func (stop chan bool) {
    close(chan)
  }(stop)

  // Make sure that the function does close the channel
  _, ok := (<-stop)
  
  // If we can recieve on the channel then it is NOT closed
  if ok {
    t.Error("Channel is not closed")
  }
}

👍🏻

why not to use atomic.Bool?

https://go.dev/play/p/GLWbVcSQc-4

I have to admit that I didn't understand all of your code in the playground, but it seems more complex and slower. It also doesn't do what the original intent of this gist is: which I interpret as reading from a channel in a non-blocking way.

General remark: I don't think it's a good idea to overload the built-in close function (the only way to close a channel).

@noamnelke I have never heard about overload in Go. the close func in this gist is just a Closer implementation

I didn't understand all of your code

so sad

The error will never occur. If the channel isn't closed the function will block forever on line 13.

It would work if you replaced line 13 with the following:

	ok := true
	select {
	case _, ok = <-stop:
	default:
	}

A select with a default clause is a non-blocking read from the channel.

POC on Go Playground

Thanks , you save my day.

❤️