Testing the RabbitMQProducer publish_message
Method
In our previous blog post, we discussed how to publish messages to RabbitMQ using the RabbitMQProducer
class. In this blog post, we will focus on testing the publish_message
method of the RabbitMQProducer
class to ensure that it functions as expected.
Setting Up the Test
To begin with, we need to set up the necessary test environment. We will be using the unittest.mock
module to create mock objects for testing. Additionally, we will capture the output using the capsys
fixture provided by pytest.
from pika.exceptions import ConnectionClosedByBroker
from producers.base import RabbitMQProducer
from unittest.mock import MagicMock
Testing the Successful Message Publishing
Let's start by testing the case where the message publishing is successful. We will create a mock connection
object and a RabbitMQProducer
instance with the mock connection. Then, we will mock the channel
object and its exchange_declare
and basic_publish
methods. Finally, we will call the publish_message
method with appropriate arguments.
def test_publish_message(capsys):
connection = MagicMock()
producer = RabbitMQProducer(connection)
channel = MagicMock()
channel.exchange_declare.return_value = None
channel.basic_publish.return_value = None
connection.get_channel.return_value = channel
exchange = "test_exchange"
routing_key = "test_routing_key"
data = {"key": "value"}
producer.publish_message(exchange=exchange, routing_key=routing_key, data=data)
channel.basic_publish.assert_called_once()
channel.exchange_declare.assert_called_once()
captured = capsys.readouterr()
assert captured.out.startswith("Message sent to exchange: ")
In the test function, we create a mock connection
object and a RabbitMQProducer
instance with the mock connection. Then, we create a mock channel
object and specify the return values for its exchange_declare
and basic_publish
methods. Next, we assign the mock channel
object to the connection's get_channel
method. After that, we define the exchange, routing key, and data for the message. Finally, we call the publish_message
method of the producer and assert that the basic_publish
and exchange_declare
methods were called once.
Testing the Failed Message Publishing
Now, let's test the case where the message publishing fails. We will use the side_effect
property of the basic_publish
method to raise a ConnectionClosedByBroker
exception. This will simulate a scenario where the connection is closed by the broker.
def test_publish_message_failed(capsys):
connection = MagicMock()
producer = RabbitMQProducer(connection)
channel = MagicMock()
channel.exchange_declare.return_value = None
channel.basic_publish.return_value = None
def side_effect(exchange, routing_key, body, properties):
raise ConnectionClosedByBroker(0, "sample")
channel.basic_publish.side_effect = side_effect
connection.get_channel.return_value = channel
exchange = "test_exchange"
routing_key = "test_routing_key"
data = {"key": "value"}
producer.publish_message(exchange=exchange, routing_key=routing_key, data=data)
captured = capsys.readouterr()
assert captured.out.startswith("Connection closed by broker. Failed to publish the message")
In this test function, we set up the same mock connection
and producer
objects. We also create a mock channel
object and specify its return values. However, this time
, we define a side_effect
function that raises a ConnectionClosedByBroker
exception when called. We assign this side_effect
function to the basic_publish
method of the channel
object. Finally, we call the publish_message
method of the producer
and assert that the expected error message is printed.
Running the Tests
To run the tests, we can use a test runner such as pytest
. With pytest
, simply execute the following command in your terminal:
pytest -v
The -v
flag enables verbose mode, which provides more detailed output during test execution.
Conclusion
In this blog post, we have covered how to test the publish_message
method of the RabbitMQProducer
class. By testing both the successful and failed scenarios, we can ensure that our message publishing functionality works correctly and handles errors gracefully. Properly testing our code helps identify and address any issues or bugs, ensuring the reliability and stability of our RabbitMQ messaging system.
Top comments (0)