SELECTIVE TEST EXECUTION AT STRIPE: FAST CI FOR A 50M-LINE RUBY MONOREPO

Summary from the TLDR Dev newsletter

Stripe manages a 50M-line Ruby monorepo by using a C++ library to track file access during tests, allowing them to run only 5% of the test suite per build. This selective execution process is made reproducible by using Monotonic Revision IDs to fetch test baselines from MongoDB without needing to traverse git history.