FIX: Don't fail when exporting chat messages from deleted channels (#23131)

plugins/chat/lib/chat/messages_exporter.rb

@@ -37,6 +37,7 @@ module Chat
     private
 
     def export(from, to)
+      Chat::Channel.unscoped do
         Chat::Message
           .unscoped
           .where(created_at: from..to)
@@ -65,3 +66,4 @@ module Chat
       end
     end
   end
+end

plugins/chat/spec/lib/chat/messages_exporter_spec.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 describe Chat::MessagesExporter do
+  context "with different kinds of channels" do
     fab!(:public_channel) { Fabricate(:chat_channel) }
     fab!(:public_channel_message_1) { Fabricate(:chat_message, chat_channel: public_channel) }
     fab!(:public_channel_message_2) { Fabricate(:chat_message, chat_channel: public_channel) }
@@ -14,8 +15,12 @@ describe Chat::MessagesExporter do
     fab!(:user_1) { Fabricate(:user) }
     fab!(:user_2) { Fabricate(:user) }
     fab!(:dm_channel) { Fabricate(:direct_message_channel, users: [user_1, user_2]) }
-  fab!(:direct_message_1) { Fabricate(:chat_message, chat_channel: private_channel, user: user_1) }
-  fab!(:direct_message_2) { Fabricate(:chat_message, chat_channel: private_channel, user: user_2) }
+    fab!(:direct_message_1) do
+      Fabricate(:chat_message, chat_channel: private_channel, user: user_1)
+    end
+    fab!(:direct_message_2) do
+      Fabricate(:chat_message, chat_channel: private_channel, user: user_2)
+    end
 
     before { deleted_message.trash! }
 
@@ -34,8 +39,25 @@ describe Chat::MessagesExporter do
       assert_exported_message(result[5], direct_message_1)
       assert_exported_message(result[6], direct_message_2)
     end
+  end
+
+  context "with messages from deleted channels" do
+    fab!(:channel) { Fabricate(:chat_channel, deleted_at: Time.now) }
+    fab!(:message) { Fabricate(:chat_message, chat_channel: channel) }
+
+    it "exports such messages" do
+      exporter = Class.new.extend(Chat::MessagesExporter)
+
+      result = []
+      exporter.chat_message_export { |data_row| result << data_row }
+
+      expect(result.length).to be(1)
+      assert_exported_message(result[0], message)
+    end
+  end
 
   def assert_exported_message(data_row, message)
+    Chat::Channel.unscoped do
       expect(data_row[0]).to eq(message.id)
       expect(data_row[1]).to eq(message.chat_channel.id)
       expect(data_row[2]).to eq(message.chat_channel.name)
@@ -51,3 +73,4 @@ describe Chat::MessagesExporter do
       expect(data_row[12]).to eq(message.last_editor.username)
     end
   end
+end