DEV: Add helpers for system testing in plugins (#19421)

Add helpers for system testing in plugins

spec/system/page_objects/components/composer.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+module PageObjects
+  module Components
+    class Composer < PageObjects::Components::Base
+      def open_new_topic
+        visit("/latest")
+        find("button#create-topic").click
+        self
+      end
+
+      def open_composer_actions
+        find(".composer-action-title .btn").click
+        self
+      end
+
+      def fill_title(title)
+        find("#reply-control #reply-title").fill_in(with: title)
+        self
+      end
+
+      def fill_content(content)
+        find("#reply-control .d-editor-input").fill_in(with: content)
+        self
+      end
+
+      def select_action(action)
+        find(action(action)).click
+        self
+      end
+
+      def create
+        find("#reply-control .btn-primary").click
+      end
+
+      def action(action_title)
+        ".composer-action-title .select-kit-collection li[title='#{action_title}']"
+      end
+
+      def button_label
+        find("#reply-control .btn-primary .d-button-label")
+      end
+    end
+  end
+end