Light weight page objects for HTML strings

1_string_page_object.rb

# If you need to simply test an HTML string for content,
# but don't want (or have) an entire Capybara session to
# render it, Capybara gives you a way to wrap the HTML in
# a Capybara::Node::Simple object with the Capybara.string
# class method. With a little Ruby sprinkled on top, you
# can have a lightweight PageObject pattern for your tests
module Pages
  class Base < DelegateClass(Capybara::Node::Simple)
    include RSpec::Matchers

    class << self
      def attribute(name, selector)
        define_method name do
          find(selector)
        end
      end
    end

    def initialize(html_string)
      super(Capybara.string(html_string))
    end
  end

  class MyRenderedPage < Base
    attribute :additional_info, ".additional-info"
    attribute :instructions, ".instructions"
    attribute :terms, ".terms"
  end
end

2_my_rendered_page_spec.rb

# Then in your spec, with this example HTML string:
#
html_string = <<~HTML
  <main>
    <div class='terms'><strong>You get three wishes.</strong></div>
    <div class='instructions'><p>Rub the lamp with a silk cloth.</p></div>
    <div class='additional-info'><small>Wishes cannot be returned.</small></div>
  </main>
HTML
#
# You can do this:

RSpec.describe MyRenderedPage do
  subject(:page) { Pages::MyRenderedPage.new(html_string) }

  it "displays additional info" do
    expect(page.additional_info).to have_content("Wishes cannot be returned.")
  end

  it "displays instructions" do
    expect(page.instructions).to have_content("Rub the lamp with a silk cloth.")
  end

  it "displays terms" do
    expect(page.terms).to have_content("You get three wishes.")
  end
end