fails:String#ascii_only? returns true for the empty String with an ASCII-compatible encoding
fails:String#ascii_only? returns false for the empty String with a non-ASCII-compatible encoding
fails:String#ascii_only? returns false for a non-empty String with non-ASCII-compatible encoding
fails:String#ascii_only? returns false when interpolating non ascii strings
fails:String#ascii_only? with ASCII only characters returns true if the encoding is UTF-8
fails:String#ascii_only? with ASCII only characters returns true if the encoding is US-ASCII
fails:String#ascii_only? with ASCII only characters returns true for all single-character UTF-8 Strings
fails:String#ascii_only? with non-ASCII only characters returns false if the encoding is ASCII-8BIT
fails:String#ascii_only? with non-ASCII only characters returns false if the String contains any non-ASCII characters
fails:String#ascii_only? with non-ASCII only characters returns false if the encoding is US-ASCII
