module Rails::Dom::Testing::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.
Public Instance Methods
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
# 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
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
# 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
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
# 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
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
# 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
Private Instance Methods
equals
must contain :minimum, :maximum and :count keys
# File lib/rails/dom/testing/assertions/selector_assertions.rb, line 270 def assert_size_match!(size, equals, css_selector, message = nil) min, max, count = equals[:minimum], equals[:maximum], equals[:count] message ||= %(Expected #{count_description(min, max, count)} matching "#{css_selector}", found #{size}.) if count assert_equal count, size, message else assert_operator size, :>=, min, message if min assert_operator size, :<=, max, message if max end end
# File lib/rails/dom/testing/assertions/selector_assertions.rb, line 264 def document_root_element raise NotImplementedError, 'Implementing document_root_element makes ' \ 'assert_select work without needing to specify an element to select from.' end
# File lib/rails/dom/testing/assertions/selector_assertions.rb, line 282 def nest_selection(selection) # Set @selected to allow nested assert_select. # Can be nested several levels deep. old_selected, @selected = @selected, selection yield @selected ensure @selected = old_selected end
# File lib/rails/dom/testing/assertions/selector_assertions.rb, line 291 def nodeset(node) if node.is_a?(Nokogiri::XML::NodeSet) node else Nokogiri::XML::NodeSet.new(node.document, [node]) end end