capybara acceptance spec helper for finding a cell in table

gistfile1.rb

def find_by_row_identifier_and_column_name(row_identifier, column_name)
  #XPath resources
  # http://msdn.microsoft.com/en-us/library/ms256086.aspx
  #
  # Figure out the column number for the given column_name
  # //th[contains(., 'Magic')]             find the first TH whose enclosing EM is 'Magic'
  # /preceding::th                          finds the collection of TH elements which appear before this one
  #                                         XML indexes start with 1 not 0, so we add 1
  column_number = 1 + all(:xpath, "//th[contains(., '#{column_name}')]/preceding::th").length

  # //td[contains(., '303-555-1212')][1]    find the first TD which contains the given row_identifier
  #                                         any text which is unique-per-row would due
  # /parent::tr                             find the TR which encloses the unique TD we just found
  # /td[#{column_number}]                   find the TD which is in the same column we located by name earlier
  find(:xpath, "//td[contains(., '#{row_identifier}')][1]/parent::tr/td[#{column_number}]")
end