Writing cloud native Python is one of the easiest ways to build an application for AWS. However, when it comes to running unit tests on your code, how do you ensure that your API calls to other AWS services don't actually change things? Thats where The Stubber comes in! A lesser-known part of AWS's python SDK Boto3, The Stubber is a way to mock your API calls and return exactly what AWS promises that you will get when you invoke their APIs without actually invoking them. This talk will cover why its important to unit test your Python AWS Lambdas, how to use the Stubber, and a demo running unit tests with the Stubber.