How to use assert_select to test for presence of a given link?

Question

My page should contain a link that looks like <a href="/desired_path/1">Click to go</a>.

How would you test for that using assert_select? I want to check for the presence of an a tag with href="/desired_path/1". How do you test the attributes of a tag?

Are there any resources to explain how to use assert_select? I read the Guides and API documentation, but didn't figure it out. Are there any recommended better ways of doing this?

I am working in Rails 3 and using the built-in test framework.

Thanks.

Answer 1

You can pass any CSS selector to assert_select. So to test the attribute of a tag, you use [attrname=attrvalue]:

assert_select("a[href=/desired_path/1]") do |elements|
   # Here you can test that elements.count == 1 for instance, or anything else
end

Answer 2

In assert_select, you can also use a question mark for the attribute value, and then follow with a string to match.

assert_select "a[href=?]", "/desired_path/1"

There's another way to use assert_select that is more friendly, especially if you want to match a partial string or regexp pattern:

assert_select "a", :href => /acebook\.com\/share/

Answer 3

Here is how you can assert a number of things about a link using assert_select. The 2nd argument can either be a String or a Regexp to test the href attribute against:

  # URL string (2nd arg) is compared to the href attribute thanks to the '?' in
  # CSS selector string. Also asserts that there is only one link matching
  # the arguments (:count option) and that the link has the text
  # 'Your Dashboard' (:text option)
  assert_select '.menu a[href=?]', 'http://test.host/dashboard',
      { :count => 1, :text => 'Your Dashboard' }

  # Regular expression (2nd arg) tests the href attribute thanks to the '?' in
  # the CSS selector string.
  assert_select '.menu a[href=?]', /\Ahttp:\/\/test.host\/dashboard\z/,
      { :count => 1, :text => 'Your Dashboard' }

For other ways you can use assert_select, here are the examples taken from the Rails actionpack 3.2.15 docs (see file actionpack-3.2.15/lib/action_dispatch/testing/assertions/selector.rb):

  # 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

Answer 4

The question specifically asks, “How do you test the attributes of [an element]?”

The other answers here use assert_select in ways that no longer work in current Rails / MiniTest. As per this issue, assertions about attribute contents now use this more Xpath-y ‘match’ syntax:

assert_select "a:match('href', ?)", /jm3\.net/

Answer 5

For anyone using assert_select coming from Rails 4.1 and upgrading to Rails 4.2.

In 4.1 this worked:

my_url = "/my_results?search=hello"
my_text = "(My Results)"
assert_select 'a[href=?]', my_url, my_text

In 4.2 this gave an error: "DEPRECATION WARNING: The assertion was not run because of an invalid css selector. unexpected '(' after '[:equal, "\"/my_results\""]'"

I changed the syntax to this and it worked!:

assert_select 'a[href=?]', my_url, { text: my_text }

Eliots answer above helped me, thanks :)

Answer 6

assert_select 'a' do |link|
  expect(link.attr('href').to_s).to eq expected_url
end