Add feature-test coverage for Rich Text Field

Follow-up to [#2411][]

Add Capybara-driven feature test coverage for filling in and rendering
the contents of a `<trix-editor>` element.

[#2411]: #2411

spec/features/products_form_spec.rb

@@ -3,7 +3,7 @@
 describe "product form has_one relationship" do
   include ActiveSupport::Testing::TimeHelpers
 
-  it "saves product and meta tag data correctly" do
+  it "saves product and meta tag data correctly", js: true do
     visit new_admin_product_path
 
     fill_in "Name", with: "Example"
@@ -12,11 +12,17 @@
     fill_in "Image url", with: "http://imageurlthatdoesnotexist"
     fill_in "Meta title", with: "Example meta title"
     fill_in "Meta description", with: "Example meta description"
+    fill_in_rich_text_area "Banner", with: <<~HTML
+      <div>A banner with a <a href="https://example.com">link</a>.</div>
+    HTML
 
     expect(page).to have_css("legend", text: "Product Meta Tag")
 
     click_on "Create Product"
 
+    within(".trix-content div", text: "A banner with a link") do
+      expect(page).to have_link("link", href: "https://example.com")
+    end
     expect(page).to have_link("Example meta title")
     expect(page).to have_flash(
       t("administrate.controller.create.success", resource: "Product")
@@ -53,13 +59,27 @@
     ProductDashboard::ATTRIBUTE_TYPES[:release_year] = old_release_year
   end
 
-  it "edits product and meta tag data correctly" do
-    product = create(:product)
+  it "edits product and meta tag data correctly", js: true do
+    product = create(:product, banner: <<~HTML)
+      <div>A banner with a <a href="https://example.com">link</a>.</div>
+    HTML
 
     visit edit_admin_product_path(product)
 
+    within(:rich_text_area, "Banner") do
+      within("div", text: "A banner with a link") do
+        expect(page).to have_link("link", href: "https://example.com")
+      end
+    end
+
+    fill_in_rich_text_area "Banner", with: <<~HTML
+      <div>A changed banner without a link.</div>
+    HTML
     click_on "Update Product"
 
+    within(".trix-content div", text: "A changed banner without a link.") do
+      expect(page).to have_no_link(href: "https://example.com")
+    end
     expect(page).to have_link(product.product_meta_tag.meta_title.to_s)
     expect(page).to have_flash(
       t("administrate.controller.update.success", resource: "Product")

spec/support/features/action_text.rb

@@ -0,0 +1,23 @@
+module Features
+  if Rails.version >= "6.1"
+    require "action_text/system_test_helper"
+
+    include ActionText::SystemTestHelper
+  else
+    def fill_in_rich_text_area(locator = nil, with:)
+      find(:rich_text_area, locator).execute_script("this.editor.loadHTML(arguments[0])", with.to_s)
+    end
+
+    Capybara.add_selector :rich_text_area do
+      xpath do |label|
+        trix_editor = XPath.descendant(:"trix-editor")
+
+        if label.nil?
+          trix_editor
+        else
+          trix_editor.where XPath.attr(:"aria-label").equals(label)
+        end
+      end
+    end
+  end
+end