xerrs   [2]error // expected errors in transition
}{
	// Tests that read deadlines work, even if there's data ready
	// to be read.
	{-5 * time.Second, [2]error{os.ErrDeadlineExceeded, os.ErrDeadlineExceeded}},

	{50 * time.Millisecond, [2]error{nil, os.ErrDeadlineExceeded}},
}

// There is a very similar copy of this in os/timeout_test.go.
func TestReadTimeout(t *testing.T) {
	handler := func(ls *localServer, ln Listener) {

	if err == nil {
		t.Errorf("client reading from truncated request body: got nil error, want non-nil")
	}
	err = <-errc // io.Copy error
	if !errors.Is(err, os.ErrDeadlineExceeded) {
		t.Errorf("server timed out writing request body: got err %v; want os.ErrDeadlineExceeded", err)
	}
}

func TestResponseControllerSetPastReadDeadline(t *testing.T) {
	run(t, testResponseControllerSetPastReadDeadline)
}

	xerrs   [2]error // expected errors in transition
}{
	// Tests that read deadlines work, even if there's data ready
	// to be read.
	{-5 * time.Second, [2]error{os.ErrDeadlineExceeded, os.ErrDeadlineExceeded}},

	{50 * time.Millisecond, [2]error{nil, os.ErrDeadlineExceeded}},
}

// There is a very similar copy of this in net/timeout_test.go.
func TestReadTimeout(t *testing.T) {
	t.Parallel()

	r, w, err := os.Pipe()

		ok       bool
	)
	expired := ffd.readDeadline.Load().expired
	select {
	case <-expired:
		return nil, os.ErrDeadlineExceeded
	case incoming, ok = <-ffd.incoming:
		if !ok {
			return nil, ErrClosed
		}
		select {
		case <-expired:
			ffd.incoming <- incoming
			return nil, os.ErrDeadlineExceeded
		default:
		}
	case incoming, ok = <-ffd.incomingFull:
		select {
		case <-expired:

	//
	// If the deadline is exceeded a call to Read or Write or to other
	// I/O methods will return an error that wraps os.ErrDeadlineExceeded.
	// This can be tested using errors.Is(err, os.ErrDeadlineExceeded).
	// The error's Timeout method will return true, but note that there
	// are other possible errors for which the Timeout method will

			// something first, we expect to get an os.ErrDeadlineExceeded error
			// here if the connection is still alive.
			// note that unlike tcp connections, reading is a good enough test here.
			_, err := conn.readMessage(time.Second / 100)
			switch {
			case !errors.Is(err, os.ErrDeadlineExceeded):
				log.Debugf("ztunnel keepalive failed: %v", err)
				if errors.Is(err, io.EOF) {

		return nil
	}
	switch err := nestedErr.(type) {
	case *os.SyscallError:
		nestedErr = err.Err
		goto third
	}
	switch nestedErr {
	case ErrClosed, errTimeout, poll.ErrNotPollable, os.ErrDeadlineExceeded:
		return nil
	}
	return fmt.Errorf("unexpected type on 2nd nested level: %T", nestedErr)

third:
	if isPlatformError(nestedErr) {
		return nil
	}

		// it didn't handle the operation, resulting in a non-sendfile retry.
		// So don't use expectSendfile here.
		_, err = io.Copy(conn, f)
		if errors.Is(err, os.ErrDeadlineExceeded) {
			return nil
		}

		if err == nil {
			err = fmt.Errorf("expected ErrDeadlineExceeded, but got nil")
		}
		return err
	}(ln)

	conn, err := Dial("tcp", ln.Addr().String())
	if err != nil {
		t.Fatal(err)
	}

	if err != nil {
		t.Fatal(err)
	}
	defer c.Close()

	c.SetDeadline(time.Now())
	b := make([]byte, 1)
	n, addr, err := c.ReadFromUDP(b)
	if !errors.Is(err, os.ErrDeadlineExceeded) {
		t.Errorf("ReadFromUDP got err %v want os.ErrDeadlineExceeded", err)
	}
	if n != 0 {
		t.Errorf("ReadFromUDP got n %d want 0", n)
	}
	if addr != nil {
		t.Errorf("ReadFromUDP got addr %+#v want nil", addr)
	}
}

// by setting a deadline in the future.
//
// If the deadline is exceeded a call to Read or Write or to other I/O
// methods will return an error that wraps ErrDeadlineExceeded.
// This can be tested using errors.Is(err, os.ErrDeadlineExceeded).
// That error implements the Timeout method, and calling the Timeout
// method will return true, but there are other possible errors for which