dualfroz
d48b259893
hour(n) with n >= 24 clamped n to 24, which walkTo() rejects as an invalid hour (valid range 0-23), nulling the epoch and invalidating the object. Clamp to 23 to match the other overflow-clamping setters (date, month).
80 lines
2.0 KiB
Markdown
80 lines
2.0 KiB
Markdown
# Fix hour() setter clamping to an invalid hour (24)
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## Problem
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Calling `.hour(n)` with `n >= 24` produces an invalid spacetime whose epoch is
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`null`, instead of clamping to a valid hour:
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```js
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const s = spacetime('2021-03-14 10:00:00', 'UTC')
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s.hour(24).isValid() // false
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s.hour(24).epoch // null
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s.hour(25).format('iso') // '' (empty - object is invalid)
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```
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This is inconsistent with every other overflow-clamping setter:
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- `.date(40)` clamps to the last day of the month,
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- `.month(13)` clamps to December (11),
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- `.hour(-1)` clamps to 0.
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Only the upper bound of `.hour()` is broken.
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## Root cause
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`src/methods/set/set.js`, in `hours()`:
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```js
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if (n >= 24) {
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n = 24
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} else if (n < 0) {
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n = 0
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}
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```
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Valid hours are `0-23`. Clamping to `24` yields a value that
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`src/methods/set/walk.js` rejects (`hour.valid: (n) => n >= 0 && n < 24`), and
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on an invalid unit `walkTo()` sets `s.epoch = null`, invalidating the whole
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object. The negative branch is already correct (clamps to the valid `0`); the
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`>= 24` branch is off by one and should clamp to `23`.
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## Fix
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```js
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if (n >= 24) {
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n = 23
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} else if (n < 0) {
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n = 0
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}
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```
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`hour(24)`, `hour(25)`, `hour(100)` now all clamp to `23:00` on the same day,
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matching the behavior of the other setters.
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## Test
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Added a test to `test/set.test.js` (next to the existing month/date clamp test)
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asserting that out-of-range hours clamp to `23`, keep the object valid, keep the
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same day, and that negatives still clamp to `0`.
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Counterfactual (revert `n = 23` back to `n = 24`):
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```
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not ok - hour(24) clamps to 23
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operator: equal
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expected: 23
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actual: 0
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```
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(the invalid object reports hour `0`).
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## Gate
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- `npm test` (tape) run against `src` (the default dev target of
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`test/lib/index.js`): the new test passes; the full suite shows only 18
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pre-existing DST/timezone failures (`europe/london`, `atlantic/madeira`,
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`atlantic/azores`, some date-dependent "dst-now") that are present verbatim
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without this change and are unrelated to it.
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- `npm run lint` (eslint ./src): exit 0.
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