fails:IO#each_char yields each character
fails:IO#each_char returns an Enumerator when passed no block
fails:IO#each_char returns itself
fails:IO#each_char returns an enumerator for a closed stream
fails:IO#each_char raises an IOError when an enumerator created on a closed stream is accessed
fails:IO#each_char raises IOError on closed stream
fails:IO#each_char does not yield any characters on an empty stream
