Setting up unit tests

As I mentioned in the prior section, there are a few tricks and tips in setting up unit tests with a serverless system. The most important thing you can do is completely isolate your application code from the fact that it is running in a serverless context or within a given cloud provider. This strategy will lend other significant benefits other than making our tests easier to run, and I'll discuss those advantages in the course of this discussion on testing.

Code organization

What does our code layout look like when we attempt to isolate application code from cloud provider-specific code? Let's take a look at the following diagram that shows the high-level structure of our REST or GraphQL API from Chapter 2, A Three-Tier Web Application Using REST, and Chapter 3, A Three-Tier Web Application Pattern with GraphQL, respectively:

Our example application was authored in Python, but this diagram shows how this general code organization can work for Node, Python, or any other...