Sample
Configure timezone strings with dateutil.tz.tzstr and posix_offset to handle POSIX offset sign inversion versus ISO-8601 conventions
sha256:1d61102c9dc6e665004c4e0e9c48b2388643d4b1c449c70394827ad9a6dab848
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
- python
- Operating system
- linux
- Architecture
- x64
- Runtime
- python
- Language
- python
- Package manager
- pip
Verification-run environments
- Execution context
- python 3.12
- Operating system
- linux alpine · musl
- Architecture
- x64
- Runtime
- python 3.12
- Language
- python
- Package manager
- pip
- Execution
- container · docker
CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · python@1 · 2026-08-17
Case
- Goal
- Configure timezone strings with dateutil.tz.tzstr and posix_offset to handle POSIX offset sign inversion versus ISO-8601 conventions HOW
- Packages
-
python-dateutil 2.9.0.post0
- Environment
- python
- Created
- 2026-08-17T10:18:50Z
Commonly assumed
Passing positive offset strings like tzstr('EST+5') or configuring posix_offset=True produces a timezone 5 hours ahead of UTC.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- tzstr('EST+5') produces an offset of -5 hours (UTC-5) per POSIX standard inversion, whereas tzstr('UTC+5') defaults to +5 hours (UTC+5) unless posix_offset=True is set
- tzstr('UTC+5') with default posix_offset=False produces +5 hours (UTC+5) while tzstr('UTC-5') produces -5 hours (UTC-5)
- tzstr('UTC+5', posix_offset=True) produces -5 hours (UTC-5) under strict POSIX compliance
- gettz() with TZ environment variable set to a POSIX string inherits tzstr parsing semantics
- tzstr with POSIX transition rules correctly switches between standard and daylight saving time offsets
Files
- NOTES.md
- csx.json
- requirements.txt
- test/contract.py
Download the source artifact (tar.gz)
Origin Seeder
csx-seed
Verification receipts
- python 3.12 · linux alpine/x64 · docker · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · python@1 · 2026-08-17 · ed25519:d91480838ac982c9