selector.rb

def assert_select(*args, &block)
  # Start with optional element followed by mandatory selector.
  arg = args.shift
  @selected ||= nil

  if arg.is_a?(HTML::Node)
    # First argument is a node (tag or text, but also HTML root),
    # so we know what we're selecting from.
    root = arg
    arg = args.shift
  elsif arg == nil
    # This usually happens when passing a node/element that
    # happens to be nil.
    raise ArgumentError, "First argument is either selector or element to select, but nil found. Perhaps you called assert_select with an element that does not exist?"
  elsif @selected
    root = HTML::Node.new(nil)
    root.children.concat @selected
  else
    # Otherwise just operate on the response document.
    root = response_from_page
  end

  # First or second argument is the selector: string and we pass
  # all remaining arguments. Array and we pass the argument. Also
  # accepts selector itself.
  case arg
    when String
      selector = HTML::Selector.new(arg, args)
    when Array
      selector = HTML::Selector.new(*arg)
    when HTML::Selector
      selector = arg
    else raise ArgumentError, "Expecting a selector as the first argument"
  end

  # Next argument is used for equality tests.
  equals = {}
  case arg = args.shift
    when Hash
      equals = arg
    when String, Regexp
      equals[:text] = arg
    when Integer
      equals[:count] = arg
    when Range
      equals[:minimum] = arg.begin
      equals[:maximum] = arg.end
    when FalseClass
      equals[:count] = 0
    when NilClass, TrueClass
      equals[:minimum] = 1
    else raise ArgumentError, "I don't understand what you're trying to match"
  end

  # By default we're looking for at least one match.
  if equals[:count]
    equals[:minimum] = equals[:maximum] = equals[:count]
  else
    equals[:minimum] = 1 unless equals[:minimum]
  end

  # Last argument is the message we use if the assertion fails.
  message = args.shift
  #- message = "No match made with selector #{selector.inspect}" unless message
  if args.shift
    raise ArgumentError, "Not expecting that last argument, you either have too many arguments, or they're the wrong type"
  end

  matches = selector.select(root)
  # If text/html, narrow down to those elements that match it.
  content_mismatch = nil
  if match_with = equals[:text]
    matches.delete_if do |match|
      text = ""
      stack = match.children.reverse
      while node = stack.pop
        if node.tag?
          stack.concat node.children.reverse
        else
          content = node.content
          text << content
        end
      end
      text.strip! unless NO_STRIP.include?(match.name)
      text.sub!(/\A\n/, '') if match.name == "textarea"
      unless match_with.is_a?(Regexp) ? (text =~ match_with) : (text == match_with.to_s)
        content_mismatch ||= sprintf("<%s> expected but was\n<%s>.", match_with, text)
        true
      end
    end
  elsif match_with = equals[:html]
    matches.delete_if do |match|
      html = match.children.map(&:to_s).join
      html.strip! unless NO_STRIP.include?(match.name)
      unless match_with.is_a?(Regexp) ? (html =~ match_with) : (html == match_with.to_s)
        content_mismatch ||= sprintf("<%s> expected but was\n<%s>.", match_with, html)
        true
      end
    end
  end
  # Expecting foo found bar element only if found zero, not if
  # found one but expecting two.
  message ||= content_mismatch if matches.empty?
  # Test minimum/maximum occurrence.
  min, max, count = equals[:minimum], equals[:maximum], equals[:count]

  # FIXME: minitest provides messaging when we use assert_operator,
  # so is this custom message really needed?
  message = message || %(Expected #{count_description(min, max, count)} matching "#{selector.to_s}", found #{matches.size}.)
  if count
    assert_equal matches.size, count, message
  else
    assert_operator matches.size, :>=, min, message if min
    assert_operator matches.size, :<=, max, message if max
  end

  # If a block is given call that block. Set @selected to allow
  # nested assert_select, which can be nested several levels deep.
  if block_given? && !matches.empty?
    begin
      in_scope, @selected = @selected, matches
      yield matches
    ensure
      @selected = in_scope
    end
  end

  # Returns all matches elements.
  matches
end