FileReader.rb

class FileReader

  def read_file(text, file_delim, field_delim)
    result = []
    lines_array = text.split([file_delim].pack('H*'))
    lines_array.each do |line|
      result << fields = line.split([field_delim].pack('H*'))
      fields.each do |field|
        puts field
      end
    end
    result
  end

  def get_file_delim(filename)
    if filename.match('.edi')
      file_delim = '0d0a'
    
    elsif filename.match('.csv')
      file_delim = '0a'
    else
      puts 'unknown file'
      file_delim = nil
    end
    return file_delim
  end

  def get_field_delim(filename)
    if filename.match('.edi')
      field_delim = '07'
    
    elsif filename.match('.csv')
      field_delim = "2c"
    else
      puts 'unknown file'
      field_delim = nil
    end
    return field_delim
  end

end

Line 3: The file name and the record delimiter should be passed in separately.

Line 15: Ruby convention would be record_delim returns the @record_delim value rather than the getter setter pattern. Really we should let the user of the class set the delimiters rather than trying to guess them. Setting reasonable defaults of \n and , would be a good idea though.