dualfroz
6bb686d4af
Instant::toISOString() and ZonedDateTime::toISOString() emitted a compact time that dropped zero seconds (e.g. 2023-11-14T22:14Z), which is valid ISO 8601 but not valid RFC 3339. Section 5.6 of RFC 3339 requires the full HH:MM:SS time even when the seconds are zero. These types are meant for interoperability, so they must always emit RFC 3339 compliant output. Build the time part of ZonedDateTime::toISOString() explicitly with a mandatory seconds component instead of delegating to LocalTime's compact formatter. Instant delegates to ZonedDateTime, so it is fixed transitively; jsonSerialize() and __toString() route through toISOString(). LocalTime's documented compact format is intentional and left unchanged. This changes the serialized string representation and is therefore a BC break; fixtures that pinned the compact output are updated accordingly.
98 lines
4.0 KiB
Markdown
98 lines
4.0 KiB
Markdown
# fix: emit full seconds in Instant and ZonedDateTime toISOString (RFC 3339)
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Fixes #110
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## Problem
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`Instant::toISOString()` (and therefore `Instant::jsonSerialize()` / `(string)`) and
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`ZonedDateTime::toISOString()` emit a compact time format that omits the seconds when they
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are zero, e.g.:
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```
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2023-11-14T22:14Z // whole minute
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1970-01-01T00:00Z // epoch
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2023-11-14T23:00Z // whole hour
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```
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This is a valid ISO 8601 time, but it is **not** a valid RFC 3339 date-time. RFC 3339
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section 5.6 defines `full-time` as `partial-time time-offset` where
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`partial-time = time-hour ":" time-minute ":" time-second [time-secfrac]` — the seconds
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component is mandatory, even when it is `00`. `Instant` and `ZonedDateTime` are the types
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meant for interoperability (JSON serialization, wire formats), so they should always emit a
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value other systems can parse as RFC 3339. Producing `2023-11-14T22:14Z` breaks strict
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RFC 3339 parsers.
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## Root cause
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The compact behavior is intentional and documented in
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`src/LocalTime.php:639` (`toISOString()` — "the shortest that outputs the full value of the
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time"). That is correct for `LocalTime` and is left untouched.
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The bug is that the interop types inherit that compact form:
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- `src/ZonedDateTime.php:740` `toISOString()` built the string from
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`$this->localDateTime`, whose `__toString()` delegates to `LocalTime::toISOString()`
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(the compact formatter).
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- `src/Instant.php:362` `toISOString()` returns `(string) ZonedDateTime::ofInstant(...)`,
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so it inherited the same compact time. `jsonSerialize()` and `__toString()` both route
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through `toISOString()`.
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## The fix
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`ZonedDateTime::toISOString()` now builds the time portion explicitly with a mandatory
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`HH:MM:SS` component (keeping the existing optional fractional-seconds handling), instead of
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delegating to `LocalTime`'s compact formatter. `Instant::toISOString()` is fixed
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transitively because it delegates to `ZonedDateTime`; its PHPDoc now documents the RFC 3339
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guarantee. `LocalTime` is deliberately not changed.
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Output after the fix:
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```
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2023-11-14T22:14:00Z
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1970-01-01T00:00:00Z
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2023-11-14T23:00:00Z
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2023-11-14T23:14:00+01:00[Europe/Paris]
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```
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Fractional seconds and non-zero seconds are unchanged (e.g.
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`1970-01-01T00:00:00.000123456Z`, `1969-12-31T23:59:59Z`).
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## Why the test fixture changes are justified (BC break)
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Some existing fixtures pinned the buggy compact output and had to be updated to the
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RFC-3339-correct strings — this is the legitimate case of changing a maintainer's tests
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because the old expected values encode the bug being fixed:
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- `tests/InstantTest.php` `providerToString`: `[0, 0, '1970-01-01T00:00Z']` ->
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`'1970-01-01T00:00:00Z'`.
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- `tests/ZonedDateTimeTest.php`: the DST plus/minus and interval result strings that landed
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on whole minutes/hours (e.g. `2025-03-30T01:00+01:00[Europe/Prague]` ->
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`2025-03-30T01:00:00+01:00[Europe/Prague]`).
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- `tests/IntervalTest.php`: one exception-message fixture (`1970-01-04T11:20Z` ->
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`1970-01-04T11:20:00Z`).
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New assertions were added for whole-minute and whole-hour values to lock in the `:00`:
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- `tests/InstantTest.php`: `[1700000040, 0, '2023-11-14T22:14:00Z']` and
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`[1700002800, 0, '2023-11-14T23:00:00Z']`.
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- `tests/ZonedDateTimeTest.php`: `['2000-01-20T12:34', '-07:00', '2000-01-20T12:34:00-07:00']`
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and `['2000-01-20T12:00', 'America/Los_Angeles', '2000-01-20T12:00:00-08:00[America/Los_Angeles]']`.
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Because the serialized string representation changes, this is technically a backward
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compatibility break, matching the maintainer's note on issue #110: "this will target
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version 0.8.0 as this is technically a BC break." Parsing is unaffected — the parser still
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accepts the compact input form, so round-tripping and existing stored values keep working.
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## Test evidence
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Gate command:
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```
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composer install && vendor/bin/phpunit
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```
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Result: exit code `0` — `OK (7865 tests, 38307 assertions)`, 0 failures.
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Before the fix, `Instant::of(1700000040, 0)->toISOString()` returned `2023-11-14T22:14Z`;
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after the fix it returns `2023-11-14T22:14:00Z`.
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