Date-time validation fails depending on local time zone

[ennoruijters]

Schema:

{
  "$id": "https://example.com/dateTimeTest.schema.json",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "array",
  "items": {
    "type": "string",
    "format": "date-time"
  }
}

Document:

[
        "2020-03-29T02:00:00Z",
        "2020-09-27T02:00:00Z",
        "2020-03-15T02:00:00Z",
        "2020-03-08T02:00:00Z",
        "2020-03-27T02:00:00Z",
        "2020-08-04T02:00:00Z"
]

This should be accepted, as all one the listed times are perfectly valid UTC times. However, on my machine (Amsterdam time), it fails with the message "$[0]: 2020-03-29T02:00:00Z is an invalid date-time".

This is because DateTimeValidator.validateDateTime does not set the time zone of the SimpleDateFormat which therefore defaults to the system time. The first date in the list was the time when daylight savings time began, so the local timed jumped to 03:00, and 02:00 never existed. The other dates in the list are times when DST started elsewhere in the world, so it should be relatively easy to test in other time zones.

Proposal: Since the RFC-3339 time format does not provide sufficient information to determine whether daylight savings time might apply (only a time zone offset can be specified), set the SimpleDateFormat to the UTC time zone, so that all valid times are accepted.

[ennoruijters]

A testcase and proposed fix are available in this branch.

[stevehu]

@ennoruijters It makes perfect sense to set the time zone. Could you please submit a PR? Thanks.

[ennoruijters]

Submitted, PR #363.