Locale Date and Time Patterns — with the four classic traps (JSON)
The structured date table plus the four traps worth their own test: day/month ambiguity in short dates, the RLM embedded in CLDR's Arabic pattern, quoted literal text inside the Russian pattern, and the localized day-period marker that a 12-hour formatter must not drop.
{
"note": "Assert on the pattern, the separator code points and the fraction-digit counts. The rendered example strings are illustrative: CLDR revises month abbreviations and spacing between releases, so a byte comparison against them will eventually fail for reasons that are not your bug.",
"instant": "2026-03-14T09:05:00",
"iso8601": "2026-03-14T09:05:00Z",
"locales": [
{
"locale": "en-US",
"patterns": {
"shortDate": "M/d/yy",
"mediumDate": "MMM d, y",
"shortTime": "h:mm a"
},
"hourCycle": "h12",
"examples": {
"shortDate": "3/14/26",
"mediumDate": "Mar 14, 2026",
"shortTime": "9:05 AM"
}
},
{
"locale": "en-GB",
"patterns": {
"shortDate": "dd/MM/y",
"mediumDate": "d MMM y",
"shortTime": "HH:mm"
},
"hourCycle": "h23",
"examples": {
"shortDate": "14/03/2026",
"mediumDate": "14 Mar 2026",
"shortTime": "09:05"
}
},
{
"locale": "de-DE",
"patterns": {
"shortDate": "dd.MM.yy",
"mediumDate": "dd.MM.y",
"shortTime": "HH:mm"
},
"hourCycle": "h23",
"examples": {
"shortDate": "14.03.26",
"mediumDate": "14.03.2026",
"shortTime": "09:05"
}
},
{
"locale": "fr-FR",
"patterns": {Specifications
- Locales
- 10
- Traps
- 4
- Instant
- 2026-03-14T09:05:00
- Assert On
- patterns, not rendered prose
- Hour Cycles
- h12, h23
- Seed
- 20260807
- Wave
- p7
- Line Endings
- LF
Testing contract
Reference control- Scenario
- Drive an Intl.DateTimeFormat / ICU comparison from the `locales` array and assert each entry in `traps` on its own.
- Expected result
- 03/04/2026 parses to two different dates under en-GB and en-US, and a formatter that treats every letter in a pattern as a field turns ru-RU's quoted 'г'. into date fields.
What is a .json file?
JSON (JavaScript Object Notation) is a lightweight, text-based data-interchange format representing objects, arrays, strings, numbers, booleans, and null. It is language-independent, human-readable, and the dominant format for web APIs and configuration. It requires a single well-formed root value.
How to use this file
Use an example JSON file to test parsers and serializers, schema validation, Unicode and number-precision handling, and API request or response processing.
How to use this file for testing
“Locale Date and Time Patterns — with the four classic traps (JSON)” is a deterministic Novus Examples fixture for Internationalization, JSON parsing, Localization catalogs. Parallel text and accented, multi-script content — for testing translation pipelines, Unicode handling, and localization tooling.
Documented properties for this file: seed 20260807 · LF. Compare results against paired or grouped companions on this page when present (clean↔damaged, searchable↔scanned, or format twins) so scores stay reproducible across runs.
Download the file once, keep the path stable in CI or local scripts, and treat the spec table as the contract: dimensions, seeds, field lists, and roles are intentional. Corrupt or invalid samples are labelled as such — expect parsers to fail loudly rather than silently accept them.
Translation-catalog fixtures carry the same message set across formats, each with its native placeholder syntax. Test your i18n loader, catalog converter, or translation-memory tool, and use the RTL and CJK variants to check bidirectional text and Unicode handling.
Load the catalog with your i18n framework and verify placeholder interpolation and plural handling; the RTL and CJK variants exercise bidirectional text and font fallback.
Code examples
import json
with open("date-time-formats.json") as f:
data = json.load(f)
print(type(data), len(data))Related files
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- jsonCLDR Plural Rules — English (2 categories)English CLDR cardinal and ordinal plural rules with the exact integer samples that select each category, the equivalent gettext Plural-Forms expression, and a note on the trap the language exposes: '1.
- jsonCLDR Plural Rules — Japanese (1 category)Japanese CLDR cardinal and ordinal plural rules with the exact integer samples that select each category, the equivalent gettext Plural-Forms expression, and a note on the trap the language exposes: japanese needs exactly one form; a pipeline that requires a 'one' key produces a catalog no japanese translator can fill in meaningfully.
- jsonCLDR Plural Rules — Polish (4 categories)Polish CLDR cardinal and ordinal plural rules with the exact integer samples that select each category, the equivalent gettext Plural-Forms expression, and a note on the trap the language exposes: cldr gives polish four categories but the traditional gettext header gives it three — gettext folds cldr 'many' and 'other' together because its rule takes an integer n and never sees v.
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