style: use verified doubles and remove receive_message_chain usage

spec/services/email/send_on_email_service_spec.rb

@@ -9,15 +9,25 @@ describe Email::SendOnEmailService do
   let(:service) { described_class.new(message: message) }
 
   describe '#perform' do
+    let(:mailer_context) { instance_double(ConversationReplyMailer) }
+    let(:delivery) { instance_double(ActionMailer::MessageDelivery) }
+
+    before do
+      allow(ConversationReplyMailer).to receive(:with).with(account: message.account).and_return(mailer_context)
+    end
+
     context 'when message is email notifiable' do
       before do
-        allow(ConversationReplyMailer).to receive_message_chain(:with, :email_reply, :deliver_now)
+        allow(mailer_context).to receive(:email_reply).with(message).and_return(delivery)
+        allow(delivery).to receive(:deliver_now)
       end
 
       it 'sends email via ConversationReplyMailer' do
         service.perform
 
         expect(ConversationReplyMailer).to have_received(:with).with(account: message.account)
+        expect(mailer_context).to have_received(:email_reply).with(message)
+        expect(delivery).to have_received(:deliver_now)
       end
     end
 
@@ -25,24 +35,28 @@ describe Email::SendOnEmailService do
       let(:message) { create(:message, conversation: conversation, message_type: 'incoming') }
 
       before do
-        allow(ConversationReplyMailer).to receive_message_chain(:with, :email_reply, :deliver_now)
+        allow(mailer_context).to receive(:email_reply)
       end
 
       it 'does not send email' do
         service.perform
 
         expect(ConversationReplyMailer).not_to have_received(:with)
+        expect(mailer_context).not_to have_received(:email_reply)
       end
     end
 
     context 'when an error occurs' do
       let(:error_message) { 'SMTP connection failed' }
       let(:error) { StandardError.new(error_message) }
+      let(:exception_tracker) { instance_double(ChatwootExceptionTracker, capture_exception: true) }
+      let(:status_service) { instance_double(Messages::StatusUpdateService, perform: true) }
 
       before do
-        allow(ConversationReplyMailer).to receive_message_chain(:with, :email_reply, :deliver_now).and_raise(error)
-        allow(ChatwootExceptionTracker).to receive(:new).and_return(double(capture_exception: true))
-        allow(Messages::StatusUpdateService).to receive(:new).and_return(double(perform: true))
+        allow(mailer_context).to receive(:email_reply).with(message).and_return(delivery)
+        allow(delivery).to receive(:deliver_now).and_raise(error)
+        allow(ChatwootExceptionTracker).to receive(:new).and_return(exception_tracker)
+        allow(Messages::StatusUpdateService).to receive(:new).and_return(status_service)
       end
 
       it 'captures the exception' do