chore: Append incoming SMS to last conversation (#4906)

- Append incoming SMS to the last conversation created for a contact

spec/services/whatsapp/incoming_message_service_spec.rb

@@ -20,6 +20,23 @@ describe Whatsapp::IncomingMessageService do
         expect(Contact.all.first.name).to eq('Sojan Jose')
         expect(whatsapp_channel.inbox.messages.first.content).to eq('Test')
       end
+
+      it 'appends to last conversation when if conversation already exisits' do
+        params = {
+          'contacts' => [{ 'profile' => { 'name' => 'Sojan Jose' }, 'wa_id' => '2423423243' }],
+          'messages' => [{ 'from' => '2423423243', 'id' => 'SDFADSf23sfasdafasdfa', 'text' => { 'body' => 'Test' },
+                           'timestamp' => '1633034394', 'type' => 'text' }]
+        }.with_indifferent_access
+
+        contact_inbox = create(:contact_inbox, inbox: whatsapp_channel.inbox, source_id: params[:messages].first[:from])
+        2.times.each { create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox) }
+        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox)
+        described_class.new(inbox: whatsapp_channel.inbox, params: params).perform
+        # no new conversation should be created
+        expect(whatsapp_channel.inbox.conversations.count).to eq(3)
+        # message appended to the last conversation
+        expect(last_conversation.messages.last.content).to eq(params[:messages].first[:text][:body])
+      end
     end
 
     context 'when valid interactive message params' do