fails:IO::foreach yields a sequence of Strings that were separated by $/
fails:IO::foreach yields a sequence of Strings that were separated by r
fails:IO::foreach yields a single string with entire content when the separator is nil
fails:IO::foreach yields a sequence of paragraphs when the separator is an empty string
fails:IO::foreach can handle non-ASCII data as separator
fails:IO::foreach converts first parameter to string and uses as file name
fails:IO::foreach converts second parameter to string and uses as separator, with each to_str calling for each lines of the IOs
fails:IO::foreach calls #to_path on non-String arguments
fails:IO::foreach returns an Enumerator when called without a block
