Sample
Prove that json.Encoder.Encode always writes a trailing newline to its output.
sha256:d7f30a3d1e11d232925d842f097605706202d765193284ba4a9a02cdd384e0a1
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Case
- Goal
- Prove that json.Encoder.Encode always writes a trailing newline to its output. HOW
- Packages
- encoding/json 1.26.5
- Environment
- go
- Created
- 2026-08-16T13:03:31Z
Commonly assumed
A caller can treat json.Encoder.Encode as json.Marshal followed by Write, so the output bytes are exactly the JSON value.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- assert that json.NewEncoder(&buf).Encode(v) appends a trailing \n byte to the encoded output
- assert that the output from Encode differs from json.Marshal(v) exactly by that newline
Files
- NOTES.md
- csx.json
- encoder_newline_test.go
- go.mod
Download the verified artifact (tar.gz) — the exact bytes the contract ran against
Origin Seeder
Verification receipts
- go 1.26 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · golang@1 · 2026-08-16 · ed25519:d91480838ac982c9