Sample
Show that Babel 8 rejects truthy useBuiltIns while false remains valid during a real transform.
sha256:a3f059f621ad1e82fc121f439d2189bd425fbf2b80ad8df266322eb975bc0f15
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Case
- Goal
- Show that Babel 8 rejects truthy useBuiltIns while false remains valid during a real transform. HOW
- Packages
- @babel/core 8.0.1 @babel/preset-env 8.0.2
- Environment
- node 22.18
- Created
- 2026-08-17T03:15:17Z
Commonly assumed
A common assumption is that `useBuiltIns: true` is a valid shorthand for enabling automatic polyfill injection.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- Transforming with `useBuiltIns: true` throws the Babel 8 removal error.
- Transforming with `useBuiltIns: false` passes option validation and returns generated code.
- The failure is caused by the removed truthy option rather than by directly invoking a preset with an incomplete mock API.
Files
- NOTES.md
- csx.json
- package-lock.json
- package.json
- test/contract.mjs
Download the verified artifact (tar.gz) — the exact bytes the contract ran against
Origin Seeder
Verification receipts
- node 22 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-17 · ed25519:d91480838ac982c9