[Python] Make AWS resources mocked with Moto into pytest fixtures

moto is a very useful tool that can mock AWS services.

If you combine this with a pytest fixture, you can automatically mock AWS services with setUp in conftest.py.

Reference-Issue with Moto and creating pytest fixture # 620

SQS example

--Create a mock queue for SQS --Send a message to the mock queue --Verify mock queue messages

import boto3
import pytest
from moto import mock_sqs
import json


@pytest.fixture()
def mock_fixture():
    """Create a queue and send one message"""
    mock = mock_sqs()
    mock.start()  #Start mock
    client = boto3.client('sqs')
    #Create a mock queue
    response = client.create_queue(QueueName='example')
    queue_url = response['QueueUrl']
    #Send message
    client.send_message(QueueUrl=queue_url,
                        MessageBody=json.dumps({'msg': 'hello'}))
    yield client, queue_url  #Transition to test here
    mock.stop()  #End of mock


def test_moto_sqs(mock_fixture):
    """Fixture test"""
    client, queue_url = mock_fixture
    messages = client.receive_message(QueueUrl=queue_url)['Messages']
    assert messages[0]['Body'] == '{"msg": "hello"}'

There are 3 points.

mock.start()
mock.stop() --The point is to generate fixtures by yield.

If you set it to return instead of yield, the teardown process (mock.stop () above) will not be executed.