useR! 2024

Tests are not only a way of catching bugs but also a way of building software. During the talk, I’ll share how we can use Test-Driven Development to build Shiny apps. We’ll start with tips on gathering requirements in a format that is easy to translate to test cases. Implementing requirements as automated tests helps us get confidence we’ve built the correct code. This is crucial when using Shiny in enterprise, when producing incorrect results may cost dearly. I’ll introduce patterns that help us separate test code from implementation details, making tests more durable. We’ll discuss ways we can shape test code to build specifications that read almost like natural language. Furthermore, we’ll talk about how to use shinytest2 effectively and what the alternatives are for robust testing of Shiny apps. Even if you don’t plan to employ Test Driven Development, you’ll be able to reuse the same patterns to produce more durable tests that document the app's behavior.