errch.go

package errch

import (
	"sync"
	)

func New() (<-chan error, func() chan<- error) {
	var (
		src = make(chan error)
		wg sync.WaitGroup
	)

	go func () {
		wg.Wait()
		close(src)
	}()

	return src, func() chan<- error{
		snk := make(chan error)

		wg.Add(1)
		go func() {
			defer wg.Done()

			if err := <-snk; err != nil{
				src <- err
			}
		}()

		return snk
	}
}

errch_test.go

package errch

import (
	"testing"
)

func TestErrCh(t *testing.T) {
	src, mkSnk := New()

	go func() {
		mkSnk() <- nil
	}()

	_, ok := <-src

	if ok {
		t.Error("expected closed src")
	}
}