# module ActionDispatch::Assertions::SelectorAssertions

Adds the `assert_select` method for use in Rails functional test cases, which can be used to make assertions on the response HTML of a controller action. You can also call `assert_select` within another `assert_select` to make assertions on elements selected by the enclosing assertion.

Use `css_select` to select elements without making an assertions, either from the response HTML or elements selected by the enclosing assertion.

In addition to HTML responses, you can make the following assertions:

- `assert_select_encoded` - Assertions on HTML encoded inside XML, for example for dealing with feed item descriptions.

- `assert_select_email` - Assertions on the HTML body of an e-mail.

Also see HTML::Selector to learn how to use selectors.

### Public Instance Methods

assert_select(*args) { |matches| ... } click to toggle source

An assertion that selects elements and makes one or more equality tests.

If the first argument is an element, selects all matching elements starting from (and including) that element and all its children in depth-first order.

If no element if specified, calling `assert_select` selects from the response HTML unless `assert_select` is called from within an `assert_select` block.

When called with a block `assert_select` passes an array of selected elements to the block. Calling `assert_select` from the block, with no element specified, runs the assertion on the complete set of elements selected by the enclosing assertion. Alternatively the array may be iterated through so that `assert_select` can be called separately for each element.

#### Example¶ ↑

If the response contains two ordered lists, each with four list elements then:

    assert_select "ol" do |elements|
      elements.each do |element|
        assert_select element, "li", 4
      end
    end

will pass, as will:

    assert_select "ol" do
      assert_select "li", 8
    end

The selector may be a CSS selector expression (String), an expression with substitution values, or an HTML::Selector object.

### Equality Tests¶ ↑

The equality test may be one of the following:

- `true` - Assertion is true if at least one element selected.

- `false` - Assertion is true if no element selected.

- `String/Regexp` - Assertion is true if the text value of at least one element matches the string or regular expression.

- `Integer` - Assertion is true if exactly that number of elements are selected.

- `Range` - Assertion is true if the number of selected elements fit the range.

If no equality test specified, the assertion is true if at least one element selected.

To perform more than one equality tests, use a hash with the following keys:

- `:text` - Narrow the selection to elements that have this text value (string or regexp).

- `:html` - Narrow the selection to elements that have this HTML content (string or regexp).

- `:count` - Assertion is true if the number of selected elements is equal to this value.

- `:minimum` - Assertion is true if the number of selected elements is at least this value.

- `:maximum` - Assertion is true if the number of selected elements is at most this value.

If the method is called with a block, once all equality tests are evaluated the block is called with an array of all matched elements.

#### Examples¶ ↑

    # At least one form element
    assert_select "form"

    # Form element includes four input fields
    assert_select "form input", 4

    # Page title is "Welcome"
    assert_select "title", "Welcome"

    # Page title is "Welcome" and there is only one title element
    assert_select "title", {:count => 1, :text => "Welcome"},
        "Wrong title or more than one title element"

    # Page contains no forms
    assert_select "form", false, "This page must contain no forms"

    # Test the content and style
    assert_select "body div.header ul.menu"

    # Use substitution values
    assert_select "ol>li#?", /item-\d+/

    # All input fields in the form have a name
    assert_select "form input" do
      assert_select "[name=?]", /.+/  # Not empty
    end

    # File lib/action_dispatch/testing/assertions/selector.rb, line 188
    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 ||= build_message(message, "<?> expected but was\n<?>.", 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 ||= build_message(message, "<?> expected but was\n<?>.", 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]
      message = message || %Q(Expected #{count_description(min, max, count)} matching "#{selector.to_s}", found #{matches.size}.)
      if count
        assert matches.size == count, message
      else
        assert matches.size >= min, message if min
        assert 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

assert_select_email(&block) click to toggle source

Extracts the body of an email and runs nested assertions on it.

You must enable deliveries for this assertion to work, use:

    ActionMailer::Base.perform_deliveries = true

#### Examples¶ ↑

    assert_select_email do
      assert_select "h1", "Email alert"
    end

    assert_select_email do
      items = assert_select "ol>li"
      items.each do
         # Work with items here...
      end
    end

    # File lib/action_dispatch/testing/assertions/selector.rb, line 414
    def assert_select_email(&block)
      deliveries = ActionMailer::Base.deliveries
      assert !deliveries.empty?, "No e-mail in delivery list"

      for delivery in deliveries
        for part in (delivery.parts.empty? ? [delivery] : delivery.parts)
          if part["Content-Type"].to_s =~ /^text\/html\W/
            root = HTML::Document.new(part.body.to_s).root
            assert_select root, ":root", &block
          end
        end
      end
    end

assert_select_encoded(element = nil, &block) click to toggle source

Extracts the content of an element, treats it as encoded HTML and runs nested assertion on it.

You typically call this method within another assertion to operate on all currently selected elements. You can also pass an element or array of elements.

The content of each element is un-encoded, and wrapped in the root element `encoded`. It then calls the block with all un-encoded elements.

#### Examples¶ ↑

    # Selects all bold tags from within the title of an ATOM feed's entries (perhaps to nab a section name prefix)
    assert_select_feed :atom, 1.0 do
      # Select each entry item and then the title item
      assert_select "entry>title" do
        # Run assertions on the encoded title elements
        assert_select_encoded do
          assert_select "b"
        end
      end
    end

    # Selects all paragraph tags from within the description of an RSS feed
    assert_select_feed :rss, 2.0 do
      # Select description element of each feed item.
      assert_select "channel>item>description" do
        # Run assertions on the encoded elements.
        assert_select_encoded do
          assert_select "p"
        end
      end
    end

    # File lib/action_dispatch/testing/assertions/selector.rb, line 363
    def assert_select_encoded(element = nil, &block)
      case element
        when Array
          elements = element
        when HTML::Node
          elements = [element]
        when nil
          unless elements = @selected
            raise ArgumentError, "First argument is optional, but must be called from a nested assert_select"
          end
        else
          raise ArgumentError, "Argument is optional, and may be node or array of nodes"
      end

      fix_content = lambda do |node|
        # Gets around a bug in the Rails 1.1 HTML parser.
        node.content.gsub(/<!\[CDATA\[(.*)(\]\]>)?/m) { Rack::Utils.escapeHTML($1) }
      end

      selected = elements.map do |_element|
        text = _element.children.select{ |c| not c.tag? }.map{ |c| fix_content[c] }.join
        root = HTML::Document.new(CGI.unescapeHTML("<encoded>#{text}</encoded>")).root
        css_select(root, "encoded:root", &block)[0]
      end

      begin
        old_selected, @selected = @selected, selected
        assert_select ":root", &block
      ensure
        @selected = old_selected
      end
    end

css_select(*args) click to toggle source

Select and return all matching elements.

If called with a single argument, uses that argument as a selector to match all elements of the current page. Returns an empty array if no match is found.

If called with two arguments, uses the first argument as the base element and the second argument as the selector. Attempts to match the base element and any of its children. Returns an empty array if no match is found.

The selector may be a CSS selector expression (String), an expression with substitution values (Array) or an HTML::Selector object.

#### Examples¶ ↑

    # Selects all div tags
    divs = css_select("div")

    # Selects all paragraph tags and does something interesting
    pars = css_select("p")
    pars.each do |par|
      # Do something fun with paragraphs here...
    end

    # Selects all list items in unordered lists
    items = css_select("ul>li")

    # Selects all form tags and then all inputs inside the form
    forms = css_select("form")
    forms.each do |form|
      inputs = css_select(form, "input")
      ...
    end

    # File lib/action_dispatch/testing/assertions/selector.rb, line 62
    def css_select(*args)
      # See assert_select to understand what's going on here.
      arg = args.shift

      if arg.is_a?(HTML::Node)
        root = arg
        arg = args.shift
      elsif arg == 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 defined?(@selected) && @selected
        matches = []

        @selected.each do |selected|
          subset = css_select(selected, HTML::Selector.new(arg.dup, args.dup))
          subset.each do |match|
            matches << match unless matches.any? { |m| m.equal?(match) }
          end
        end

        return matches
      else
        root = response_from_page
      end

      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

      selector.select(root)
    end

### Protected Instance Methods

response_from_page() click to toggle source

`assert_select` and `css_select` call this to obtain the content in the HTML page.

    # File lib/action_dispatch/testing/assertions/selector.rb, line 430
    def response_from_page
      html_document.root
    end