Testing R Packages

This covers modern testthat 3+ patterns for R package testing, written by Garrick Aden-Buie. It's structured around the practical stuff: self-sufficient tests with withr for cleanup, snapshot testing for complex output, fixture patterns, and mocking with local_mocked_bindings. The guidance on test organization (mirroring your R/ structure) and the three scales of running tests (micro/mezzo/macro) is immediately useful. What I like is it pushes you toward better habits, repetition over clever abstractions, tests that work in isolation, and the load_all workflow instead of library calls. If you're writing or improving R package tests, this gives you the modern patterns without the philosophy lectures.