FEATURE: Add new don't feed the trolls feature (#21001)

Responding to negative behaviour tends to solicit more of the same. Common wisdom states: "don't feed the trolls".

This change codifies that advice by introducing a new nudge when hitting the reply button on a flagged post. It will be shown if either the current user, or two other users (configurable via a site setting) have flagged the post.

spec/system/composer/dont_feed_the_trolls_popup_spec.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+describe "Composer don't feed the trolls popup", type: :system, js: true do
+  fab!(:user) { Fabricate(:user) }
+  fab!(:troll) { Fabricate(:user) }
+  fab!(:topic) { Fabricate(:topic, user: user) }
+  fab!(:post) { Fabricate(:post, user: user, topic: topic) }
+  fab!(:reply) { Fabricate(:post, user: troll, topic: topic) }
+  fab!(:flag) { Fabricate(:flag, post: reply, user: user) }
+  let(:topic_page) { PageObjects::Pages::Topic.new }
+
+  before { sign_in user }
+
+  it "shows a popup when about to reply to a troll" do
+    SiteSetting.educate_until_posts = 0
+
+    topic_page.visit_topic(topic)
+    topic_page.click_post_action_button(reply, :reply)
+
+    expect(topic_page).to have_composer_popup_content(I18n.t("education.dont_feed_the_trolls"))
+  end
+end

spec/system/page_objects/components/composer.rb

@@ -43,6 +43,10 @@ module PageObjects
         composer_input.value == content
       end
 
+      def has_popup_content?(content)
+        composer_popup.has_content?(content)
+      end
+
       def select_action(action)
         find(action(action)).click
         self
@@ -83,6 +87,10 @@ module PageObjects
       def composer_input
         find("#{COMPOSER_ID} .d-editor .d-editor-input")
       end
+
+      def composer_popup
+        find("#{COMPOSER_ID} .composer-popup")
+      end
     end
   end
 end

spec/system/page_objects/pages/topic.rb

@@ -71,6 +71,8 @@ module PageObjects
         case button
         when :bookmark
           post_by_number(post).find(".bookmark.with-reminder").click
+        when :reply
+          post_by_number(post).find(".post-controls .reply").click
         end
       end
 
@@ -111,6 +113,10 @@ module PageObjects
         @composer_component.has_content?(content)
       end
 
+      def has_composer_popup_content?(content)
+        @composer_component.has_popup_content?(content)
+      end
+
       def send_reply
         find("#reply-control .save-or-cancel .create").click
       end