Practitioner (own blog/paper) Test migration
Airbnb migrates ~3.5K Enzyme test files to React Testing Library in 6 weeks with LLMs
Airbnb built a per-file, state-machine migration pipeline with validation steps (Jest, lint, tsc), retry loops and prompts of 40K–100K tokens. 75% of files migrated in the first 4-hour bulk run; 4 days of 'sample, tune, sweep' reached 97%; the rest were fixed by hand in about another week.
The numbers (as reported)
| Test files migrated | ~3,500 |
|---|---|
| Actual duration | 6 weeks |
| Manual estimate | 1.5 years of engineering time |
| Auto-migrated in first bulk run | 75% in 4 hours |
| After 4 days of prompt tuning | 97% |
| Prompt size | 40,000–100,000 tokens |
Facts
- Company / subject
- Airbnb
- Tools
- Frontier LLMs (unnamed)
- Codebase
- brownfield
- Work type
- Test migration
- Stack
- React, TypeScript, Enzyme, React Testing Library, Jest
- Published
- 2025-03
- Last checked
- 2026-10-17
Caveats
Model names and dollar cost not disclosed. Published date is approximate (March 2025, per InfoQ coverage).