feat: Support sending and receiving attachments in Slack Integration (#3022)

- Process incoming slack attachments
- Send attachments from chatwoot to slack

spec/lib/integrations/slack/incoming_message_builder_spec.rb

@@ -3,6 +3,7 @@ require 'rails_helper'
 describe Integrations::Slack::IncomingMessageBuilder do
   let(:account) { create(:account) }
   let(:message_params) { slack_message_stub }
+  let(:message_with_attachments) { slack_attachment_stub }
   let(:message_without_thread_ts) { slack_message_stub_without_thread_ts }
   let(:verification_params) { slack_url_verification_stub }
 
@@ -51,6 +52,17 @@ describe Integrations::Slack::IncomingMessageBuilder do
         builder.perform
         expect(conversation.messages.count).to eql(messages_count)
       end
+
+      it 'saves attachment if params files present' do
+        expect(hook).not_to eq nil
+        messages_count = conversation.messages.count
+        builder = described_class.new(message_with_attachments)
+        allow(builder).to receive(:sender).and_return(nil)
+        builder.perform
+        expect(conversation.messages.count).to eql(messages_count + 1)
+        expect(conversation.messages.last.content).to eql('this is test https://chatwoot.com Hey @Sojan Test again')
+        expect(conversation.messages.last.attachments).to be_any
+      end
     end
   end
 end