FIX: instantly removes group message when leaving (#25961)

Prior to this fix clicking <kbd>x</kdb> on a channel row would effectively leave the channel on server side, but it wouldn't disappear from the screen before a page refresh.

plugins/chat/spec/system/page_objects/chat/components/channel_row.rb

@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+module PageObjects
+  module Components
+    module Chat
+      class ChannelRow < PageObjects::Components::Base
+        SELECTOR = ".chat-channel-row"
+
+        attr_reader :id
+
+        def initialize(id)
+          @id = id
+        end
+
+        def non_existent?(**args)
+          exists?(**args, does_not_exist: true)
+        end
+
+        def exists?(**args)
+          selector = build_selector(**args)
+          selector_method = args[:does_not_exist] ? :has_no_selector? : :has_selector?
+          page.send(selector_method, selector)
+        end
+
+        def leave
+          component(class: ".can-leave").hover
+          btn = component.find(".chat-channel-leave-btn", visible: :all)
+          # style manipulation is necessary to have it working with @media(hover: hover) on CI
+          page.execute_script(
+            "document.querySelector('#{build_selector} .chat-channel-leave-btn').style.display = 'block';",
+          )
+          btn.click
+          page.execute_script(
+            "document.querySelector('#{build_selector} .chat-channel-leave-btn').style.display = '';",
+          )
+        end
+
+        def component(**args)
+          find(build_selector(**args))
+        end
+
+        private
+
+        def build_selector(**args)
+          selector = SELECTOR
+          selector += args[:class] if args[:class]
+          selector += "[data-chat-channel-id=\"#{self.id}\"]" if self.id
+          selector
+        end
+      end
+    end
+  end
+end

plugins/chat/spec/system/page_objects/chat_drawer/chat_drawer.rb

@@ -24,6 +24,16 @@ module PageObjects
         find("#{VISIBLE_DRAWER} .c-navbar__back-button").click
       end
 
+      def visit_index
+        visit("/")
+        PageObjects::Pages::Chat.new.open_from_header
+      end
+
+      def visit_channel(channel)
+        visit_index
+        open_channel(channel)
+      end
+
       def open_channel(channel)
         channel_index.open_channel(channel)
         has_no_css?(".chat-skeleton")