Test of sending & receiving message for Azure Service Bus Queue

I would like to write an integration test checking connection of the Python script with Azure Service Bus queue. The test should:

1. send a message to a queue,
2. confirm that the message landed in the queue.

The test looks like this:

import pytest

from azure.servicebus import ServiceBusClient, ServiceBusMessage, ServiceBusSender

CONNECTION_STRING = <some connection string>
QUEUE = <queue name>


def send_message_to_service_bus(sender: ServiceBusSender, msg: str) -> None:
    message = ServiceBusMessage(msg)
    sender.send_message(message)


class TestConnectionWithQueue:
    def test_message_is_sent_to_queue_and_received(self):
        msg = "test message sent to queue"
        expected_message = ServiceBusMessage(msg)
        
        servicebus_client = ServiceBusClient.from_connection_string(conn_str=CONNECTION_STRING, logging_enable=True)
        with servicebus_client:
            sender = servicebus_client.get_queue_sender(queue_name=QUEUE)
            with sender:
                send_message_to_service_bus(sender, expected_message)
        
            receiver = servicebus_client.get_queue_receiver(queue_name=QUEUE)
            with receiver:
                messages_in_queue = receiver.receive_messages(max_message_count=10, max_wait_time=20)
        assert any(expected_message == str(actual_message) for actual_message in messages_in_queue)

The test occassionally works, more often than not it doesn't. There are no other messages sent to the queue at the same time. As I debugged the code, if the test does not work, the variable messages_in_queue is just an empty list.

Why doesn't the code work at all times and what should be done to fix it?

from Test of sending & receiving message for Azure Service Bus Queue