method

assert_select

rails latest stable - Class: ActionDispatch::Assertions::SelectorAssertions

assert_select(*args, &block)

public

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.

# 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 actionpack/lib/action_dispatch/testing/assertions/selector.rb, line 184
      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 count, matches.size, 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

assert_select

Method deprecated or moved

Example

Equality Tests

Related methods