_, err = r.ReadSlice(0)
	if err != io.EOF {
		t.Error("unexpected error on ReadSlice (4):", err)
	}
	if r.UnreadRune() == nil {
		t.Error("expected error after ReadSlice (4)")
	}
}

func TestUnreadRuneAtEOF(t *testing.T) {
	// UnreadRune/ReadRune should error at EOF (was a bug; used to panic)
	r := NewReader(strings.NewReader("x"))
	r.ReadRune()
	r.ReadRune()
	r.UnreadRune()
	_, _, err := r.ReadRune()