Module: Rails::Dom::Testing::Assertions::SelectorAssertions

Includes:
CountDescribable
Included in:
Rails::Dom::Testing::Assertions
Defined in:
lib/rails/dom/testing/assertions/selector_assertions.rb,
lib/rails/dom/testing/assertions/selector_assertions/count_describable.rb

Overview

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.

Defined Under Namespace

Modules: CountDescribable

Instance Method Summary collapse

Instance Method Details

#assert_select(*args, &block) ⇒ Object

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 is specified assert_select selects from the element returned in document_root_element unless assert_select is called from within an assert_select block. Override document_root_element to tell assert_select what to select from. The default implementation raises an exception explaining this.

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) or an expression with substitution values (Array). Substitution uses a custom pseudo class match. Pass in whatever attribute you want to match (enclosed in quotes) and a ? for the substitution. assert_select returns nil if called with an invalid css selector.

assert_select “div:match('id', ?)”, /d+/

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:match('id', ?)", /item-\d+/

# All input fields in the form have a name
assert_select "form input" do
  assert_select ":match('name', ?)", /.+/  # Not empty
end

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# File 'lib/rails/dom/testing/assertions/selector_assertions.rb', line 161

def assert_select(*args, &block)
  @selected ||= nil

  selector = HTMLSelector.new(args, @selected) { nodeset document_root_element }

  if selector.selecting_no_body?
    assert true
    return
  end

  selector.select.tap do |matches|
    assert_size_match!(matches.size, selector.tests,
      selector.css_selector, selector.message)

    nest_selection(matches, &block) if block_given? && !matches.empty?
  end
end

#assert_select_email(&block) ⇒ Object

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

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

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# File 'lib/rails/dom/testing/assertions/selector_assertions.rb', line 247

def assert_select_email(&block)
  deliveries = ActionMailer::Base.deliveries
  assert !deliveries.empty?, "No e-mail in delivery list"

  deliveries.each do |delivery|
    (delivery.parts.empty? ? [delivery] : delivery.parts).each do |part|
      if part["Content-Type"].to_s =~ /^text\/html\W/
        root = Nokogiri::HTML::DocumentFragment.parse(part.body.to_s)
        assert_select root, ":root", &block
      end
    end
  end
end

#assert_select_encoded(element = nil, &block) ⇒ Object

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.

# Selects all bold tags from within the title of an Atom feed's entries (perhaps to nab a section name prefix)
assert_select "feed[xmlns='http://www.w3.org/2005/Atom']" 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 "rss[version=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

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# File 'lib/rails/dom/testing/assertions/selector_assertions.rb', line 211

def assert_select_encoded(element = nil, &block)
  if !element && !@selected
    raise ArgumentError, "Element is required when called from a nonnested assert_select"
  end

  content = nodeset(element || @selected).map do |elem|
    elem.children.select do |child|
      child.cdata? || (child.text? && !child.blank?)
    end.map(&:content)
  end.join

  selected = Nokogiri::HTML::DocumentFragment.parse(content)
  nest_selection(selected) do
    if content.empty?
      yield selected
    else
      assert_select ":root", &block
    end
  end
end

#css_select(*args) ⇒ Object

Select and return all matching elements.

If called with a single argument, uses that argument as a selector. Called without an element css_select selects from the element returned in document_root_element

The default implementation of document_root_element raises an exception explaining this.

Returns an empty Nokogiri::XML::NodeSet if no match is found.

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

The selector may be a CSS selector expression (String). css_select returns nil if called with an invalid css selector.

# 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

Raises:

  • (ArgumentError)

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# File 'lib/rails/dom/testing/assertions/selector_assertions.rb', line 59

def css_select(*args)
  raise ArgumentError, "you at least need a selector argument" if args.empty?

  root = args.size == 1 ? document_root_element : args.shift

  nodeset(root).css(args.first)
end