_, err = tconn.Write([]byte("foo"))
	if err != errConnClosed {
		t.Errorf("Write error = %v; want errConnClosed", err)
	}

	<-closeReturned
	if err := tconn.Close(); err != net.ErrClosed {
		t.Errorf("Close error = %v; want net.ErrClosed", err)
	}
}

func TestConnCloseWrite(t *testing.T) {
	ln := newLocalListener(t)
	defer ln.Close()

	clientDoneChan := make(chan struct{})

// [Conn.SetWriteDeadline].
func (c *Conn) Write(b []byte) (int, error) {
	// interlock with Close below
	for {
		x := c.activeCall.Load()
		if x&1 != 0 {
			return 0, net.ErrClosed
		}
		if c.activeCall.CompareAndSwap(x, x+2) {
			break
		}
	}
	defer c.activeCall.Add(-2)

	if err := c.Handshake(); err != nil {
		return 0, err
	}

	c.out.Lock()

		_, err := io.Copy(stdin, strings.NewReader(stdinCloseTestString))
		check("Copy", err)

		// Before the fix, this next line would race with cmd.Wait.
		if err := stdin.Close(); err != nil && !errors.Is(err, os.ErrClosed) {
			t.Errorf("Close: %v", err)
		}
	}()

	check("Wait", cmd.Wait())
}

// Issue 17647.
// It used to be the case that TestStdinClose, above, would fail when

			msg, err = readDataInto(msg, conn, c.side, ws.OpBinary)
			if err != nil {
				cancel(ErrDisconnected)
				if !xnet.IsNetworkOrHostDown(err, true) {
					gridLogIfNot(ctx, fmt.Errorf("ws read: %w", err), net.ErrClosed, io.EOF)
				}
				return
			}
			block := c.blockMessages.Load()
			if block != nil && *block != nil {
				<-*block
			}

			if c.incomingBytes != nil {
				c.incomingBytes(int64(len(msg)))

		{"(FileMode).IsRegular", Method, 16},
		{"(FileMode).Perm", Method, 16},
		{"(FileMode).String", Method, 16},
		{"(FileMode).Type", Method, 16},
		{"DirEntry", Type, 16},
		{"ErrClosed", Var, 16},
		{"ErrExist", Var, 16},
		{"ErrInvalid", Var, 16},
		{"ErrNotExist", Var, 16},
		{"ErrPermission", Var, 16},
		{"FS", Type, 16},
		{"File", Type, 16},
		{"FileInfo", Type, 16},

					return err
				}
				reader = in
				defer func() {
					if errClose := in.Close(); errClose != nil {
						log.Errorf("Error: close file from %s, %s", inFilename, errClose)

						// don't overwrite the previous error
						if err == nil {
							err = errClose
						}
					}
				}()
			}

			var writer io.Writer
			if outFilename == "" {

// isClosedConnError reports whether err is an error from use of a closed
// network connection.
func http2isClosedConnError(err error) bool {
	if err == nil {
		return false
	}

	if errors.Is(err, net.ErrClosed) {
		return true
	}

	// TODO(bradfitz): x/tools/cmd/bundle doesn't really support
	// build tags, so I can't make an http2_windows.go file with
	// Windows-specific stuff. Fix that and move this, once we

pkg io/fs, type WalkDirFunc func(string, DirEntry, error) error
pkg io/fs, var ErrClosed error
pkg io/fs, var ErrExist error
pkg io/fs, var ErrInvalid error
pkg io/fs, var ErrNotExist error
pkg io/fs, var ErrPermission error
pkg io/fs, var SkipDir error
pkg log, func Default() *Logger
pkg net, var ErrClosed error
pkg net/http, func FS(fs.FS) FileSystem

	pw.Close()
	<-gotRes
}

type wgReadCloser struct {
	io.Reader
	wg     *sync.WaitGroup
	closed bool
}

func (c *wgReadCloser) Close() error {
	if c.closed {
		return net.ErrClosed
	}
	c.closed = true
	c.wg.Done()
	return nil
}

// Issue 11745.
func TestTransportPrefersResponseOverWriteError(t *testing.T) {
	// Not parallel: modifies the global rstAvoidanceDelay.

type TestCloseErrorPlugin struct {
	name string
}

func (pl *TestCloseErrorPlugin) Name() string {
	return pl.name
}

var errClose = errors.New("close err")

func (pl *TestCloseErrorPlugin) Close() error {
	return errClose
}

// TestPreFilterPlugin only implements PreFilterPlugin interface.
type TestPreFilterPlugin struct {
	PreFilterCalled int
}