There are a few different approaches to testing in the spectrum between simple unit tests and complete E2E tests. If I had to choose one approach to prioritize I would pick integration tests. The key reasons are: Tests a flow of multiple functions, in contrast with unit tests where only a single function is tested Self contained i.e. the test has no external dependencies on a deployed environment etc. Makes logical sense to test a complete function in a REST api, a single Lambda in AWS or an Azure function The problem In my case the goal was to setup a test suite for a .

One of the projects we work with at Devies is related to the dental domain. In that project we use the dental notation (ISO 3950) to refer to teeth. Every tooth have an unique identifier that consist of two characters. The first character represent a quadrant (one of four areas in the mouth). The second character is an identifier that refers to one of the eight teeth in that area.