THE DEATH OF TRADITIONAL TESTING: AGENTIC DEVELOPMENT BROKE A 50-YEAR-OLD FIELD, JITTESTING CAN REVIVE IT

Summary from the TLDR Dev newsletter

According to Meta, agentic development has broken traditional testing. Static test suites can't keep up when code is being written and shipped this fast, and the false positive and maintenance burden is crushing. Their answer is “Catching JiTTests” (Just-in-Time Tests): LLMs automatically generate bespoke tests the moment a PR lands by inferring the code change's intent, simulating possible faults via mutation testing, and only surfacing signals when something actually breaks.