test(format/date-time): add trailing newline as invalid

[vtushar06]

Following the methodology I used for ipv4 and uuid, I read RFC 3339 section 5.6 and found the suite has no date-time test for a trailing newline.

RFC 3339 section 5.6 defines date-time = full-date "T" full-time, and every production is a fixed sequence of digits and literals ending at the time-offset - the grammar emits no line feed, so nothing may follow the offset. A single trailing \n is therefore invalid. The suite tests a trailing space (Z ) and trailing content (Z extra), both of which the reference validator rejects; it does not test the newline, which the reference validator accepts.

Changes

• Added 1 test case across draft3, draft4, draft6, draft7, draft2019-09, draft2020-12, and v1.
• 1985-04-12T23:20:50Z\n - a valid date-time followed by a single line feed - invalid.

Ecosystem Impact

1. python-jsonschema 4.25.1: FAILS (accepts it). Its date-time check delegates to rfc3339-validator, which builds RFC3339_REGEX + "$" and calls re.match; Python's $ matches immediately before a single trailing \n, so the line feed is never seen. Z and Z extra get rejected, but Z\n slips through.
2. ajv-formats 3.0.1 (full and fast): PASSES (rejects it). JavaScript $ without the m flag matches only at the very end of the string, so the trailing \n is not consumed.
3. sourcemeta/core is_rfc3339_datetime: PASSES (rejects it) - it requires the whole string to parse.
4. Corroboration: jsonschema-rs 0.45.0, boon 0.6.1, santhosh-tekuri/jsonschema v6.0.2, and @hyperjump/json-schema 1.17.6 (four more JSON Schema validators, each with its own RFC 3339 parser) all reject it - so python-jsonschema is the lone outlier.

RFC References

• RFC 3339 section 5.6 (Internet Date/Time Format): https://www.rfc-editor.org/rfc/rfc3339#section-5.6

Reproduction and the date-time cross-implementation matrix are in my evidence repo: https://github.com/vtushar06/JSON-Schema-format-test-Evidence/blob/main/date-time.md

Related: #965

[Copilot]

Pull request overview

This PR expands the JSON Schema Test Suite’s date-time format coverage by adding a negative test case for RFC 3339 date-time strings that include a single trailing line feed (\n), ensuring validators reject input with any trailing characters after the time offset.

Changes:

• Added an invalid date-time format test for a trailing newline: "1985-04-12T23:20:50Z\n" (expected valid: false).
• Applied the same test addition consistently across draft3/draft4/draft6/draft7/draft2019-09/draft2020-12 optional suites and the v1 suite.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/v1/format/date-time.json	Adds an invalid trailing-newline date-time test case to the v1 suite.
tests/draft7/optional/format/date-time.json	Adds the same invalid trailing-newline date-time test case for draft7 optional format tests.
tests/draft6/optional/format/date-time.json	Adds the same invalid trailing-newline date-time test case for draft6 optional format tests.
tests/draft4/optional/format/date-time.json	Adds the same invalid trailing-newline date-time test case for draft4 optional format tests.
tests/draft3/optional/format/date-time.json	Adds the same invalid trailing-newline date-time test case for draft3 optional format tests.
tests/draft2020-12/optional/format/date-time.json	Adds the same invalid trailing-newline date-time test case for draft2020-12 optional format tests.
tests/draft2019-09/optional/format/date-time.json	Adds the same invalid trailing-newline date-time test case for draft2019-09 optional format tests.

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[jviotti]

I guess this is a good example of how weird regexes can get across languages, confusing users of pattern, etc