Sample
Measure absent, nil, empty-list, and empty-string header handling in Req 0.7.2
sha256:e52f4de61ddb61a20d40120fde5ea4fc51435b5e9ee5588d1f4eeeafe309ba51
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Execution evidence
Declared environment and signed verification runs are separated so you can see exactly what this sample proves.
Evidence basisSigned contract pass
Verification receipts1
Verification levelL3_CONTRACT_PASS
Declared environment
- Execution context
- elixir 1
- Operating system
- linux
- Architecture
- x64
- Runtime
- elixir 1
- Language
- elixir
- Package manager
- mix
Verification-run environments
- Execution context
- elixir 1
- Operating system
- linux alpine · musl
- Architecture
- x64
- Runtime
- elixir 1
- Language
- elixir
- Package manager
- mix
- Execution
- container · docker
CONTAINER_RUN · compile:PASS · contract:PASS · load:PASS · resolve:PASS · hex@1 · 2026-08-17
Case
- Goal
- Measure absent, nil, empty-list, and empty-string header handling in Req 0.7.2 HOW
- Packages
-
req 0.7.2
- Environment
- elixir 1
- Created
- 2026-08-17T04:47:37Z
Commonly assumed
A nil or empty-list Req header is absent from the internal map, so put_new_header supplies a fallback and get_header distinguishes it from a missing header.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- assert Req.new retains nil and empty-list header keys with empty-list values while get_header returns [] for both those keys and missing keys
- assert put_new_header leaves an existing empty-list value unchanged but populates a genuinely missing key
- assert put_header and put_headers replace an existing empty-list value
- assert an empty string is stored as one empty string value and is not replaced by put_new_header
- assert atom header keys hyphenate underscores while string keys preserve underscores as a separate key
- assert the offline adapter sees no flattened wire entries for nil and empty-list headers but sees valid and empty-string headers
Files
- NOTES.md
- csx.json
- mix.exs
- mix.lock
- test/contract.exs
- test/contract_test.exs
- test/test_helper.exs
Download the source artifact (tar.gz)
Origin Seeder
csx-seed
Verification receipts
- elixir 1 · linux alpine/x64 · docker · CONTAINER_RUN · compile:PASS · contract:PASS · load:PASS · resolve:PASS · hex@1 · 2026-08-17 · ed25519:d91480838ac982c9