defer ln.Close()

	errc := make(chan error, 1)
	defer func() {
		if err := <-errc; err != nil {
			t.Error(err)
		}
	}()
	go func() {
		c, err := ln.Accept()
		if err != nil {
			errc <- err
			return
		}
		defer c.Close()

		buf := make([]byte, 100)
		n, err := io.ReadFull(c, buf)
		if err != io.ErrUnexpectedEOF || n != 2 {

Austin Clements <******@****.***> 1683216807 -0400

	}
	defer l.Close()

	errCh := make(chan error)
	go func() {
		defer close(errCh)
		conn, err := l.Accept()
		if err != nil {
			errCh <- fmt.Errorf("Accept: %v", err)
			return
		}
		defer conn.Close()

		tc := textproto.NewConn(conn)
		tc.PrintfLine("220 hello world")
		msg, err := tc.ReadLine()
		if err != nil {
			errCh <- fmt.Errorf("ReadLine error: %v", err)
			return

	"sync"
	"testing"
	"time"
)

func Test_newReady(t *testing.T) {
	errCh := make(chan error, 10)
	ready := newReady()
	ready.set(false)
	// create 10 goroutines waiting for ready
	for i := 0; i < 10; i++ {
		go func() {
			errCh <- ready.wait(context.Background())
		}()
	}
	select {
	case <-time.After(1 * time.Second):
	case <-errCh:
		t.Errorf("ready should be blocking")
	}
	ready.set(true)

import (
	"context"
	"errors"
	"testing"
)

func TestErrorChannel(t *testing.T) {
	errCh := NewErrorChannel()

	if actualErr := errCh.ReceiveError(); actualErr != nil {
		t.Errorf("expect nil from err channel, but got %v", actualErr)
	}

	err := errors.New("unknown error")
	errCh.SendError(err)
	if actualErr := errCh.ReceiveError(); actualErr != err {
		t.Errorf("expect %v from err channel, but got %v", err, actualErr)
	}

}

func ExampleJoin() {
	err1 := errors.New("err1")
	err2 := errors.New("err2")
	err := errors.Join(err1, err2)
	fmt.Println(err)
	if errors.Is(err, err1) {
		fmt.Println("err is err1")
	}
	if errors.Is(err, err2) {
		fmt.Println("err is err2")
	}
	// Output:
	// err1
	// err2
	// err is err1
	// err is err2
}

func ExampleIs() {
	if _, err := os.Open("non-existing"); err != nil {

// are ignored, unless the existing error is received and the channel becomes empty
// again.
type ErrorChannel struct {
	errCh chan error
}

// SendError sends an error without blocking the sender.
func (e *ErrorChannel) SendError(err error) {
	select {
	case e.errCh <- err:
	default:
	}
}

// SendErrorWithCancel sends an error without blocking the sender and calls
// cancel function.

		case clHeader != "":
			cl, err := strconv.ParseInt(clHeader, 10, 64)
			if err != nil {
				errCh <- fmt.Errorf("net/http: ill-formed Content-Length header: %v", err)
				return nil
			}
			if cl < 0 {
				// Content-Length values less than 0 are invalid.
				// See: https://datatracker.ietf.org/doc/html/rfc2616/#section-14.13
				errCh <- fmt.Errorf("net/http: invalid Content-Length header: %q", clHeader)
				return nil
			}

	}
}

func TestJoin(t *testing.T) {
	err1 := errors.New("err1")
	err2 := errors.New("err2")
	for _, test := range []struct {
		errs []error
		want []error
	}{{
		errs: []error{err1},
		want: []error{err1},
	}, {
		errs: []error{err1, err2},
		want: []error{err1, err2},
	}, {
		errs: []error{err1, nil, err2},
		want: []error{err1, err2},
	}} {

	ln := newLocalListener(t, "tcp")
	defer ln.Close()

	errc := make(chan error, 1)
	go func(ln Listener) {
		// Wait for a connection.
		conn, err := ln.Accept()
		if err != nil {
			errc <- err
			close(errc)
			return
		}

		go func() {
			defer close(errc)
			defer conn.Close()

			f, err := os.Open(newton)
			if err != nil {
				errc <- err
				return
			}
			defer f.Close()