MIGRATING 6000 REACT TESTS USING AI AGENTS AND ASTS

Summary from the TLDR Dev newsletter

Elio used Claude Code to migrate 970 test files (6,000+ tests) from React Testing Library v13 to v14 in just one week. Its team had Claude build a detailed migration guide first. They created an AST codemod to handle mechanical changes, then let Claude iteratively migrate 10 tests at a time while automatically running tests and checking coverage.