908058038a
Live bill INV-2608-T5EDD-00116 carried billedat 2026-08-05T12:49:28Z beside receivedat 2026-08-05T07:19:28Z — the sale appearing to have been rung five and a half hours after the back office received it. Exactly the IST offset, on every bill. Nothing was lying. DateTime.toIso8601String() on a local time emits no zone marker at all, and Go's time.Parse fills that silence with UTC, so a Coimbatore wall clock was recorded as though it had been read in London. The daily figures survived by luck: businessdate is derived from the wall clock either way, and the wall clock was always the till's own, so a day's takings landed on the right day even while the instant was wrong. Anything comparing billedat against real time did not. Formatters.isoWithOffset attaches the offset, which fixes both readings at once — the instant parses correctly and the local date still formats correctly. The minutes come from the real offset rather than being assumed zero, because India is +05:30 and a whole-hour implementation would be wrong in a way that looks almost right. Applied to all six timestamps the till sends. date_of_birth is left alone: a birthday is a date, not an instant, and giving it a zone would be meaningless. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
77 lines
3.0 KiB
Dart
77 lines
3.0 KiB
Dart
import 'package:flutter_test/flutter_test.dart';
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import 'package:nearle_pos/core/utils/formatters.dart';
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/// The fault these cover was found in live data, not in a test.
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///
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/// Bill INV-2608-T5EDD-00116 carried `billedat 2026-08-05T12:49:28.245Z` beside
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/// `receivedat 2026-08-05T07:19:28.586Z` — the bill appearing to have been rung
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/// five and a half hours *after* the back office received it. Exactly the IST
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/// offset, every time.
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///
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/// Nothing was lying. `DateTime.toIso8601String()` on a local time emits no
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/// zone marker at all, Go's `time.Parse` fills that silence with UTC, and the
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/// till's wall clock was recorded as though it had been read in London.
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void main() {
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group('a timestamp says which zone it was read in', () {
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test('carries an explicit offset', () {
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final iso = Formatters.isoWithOffset(DateTime(2026, 8, 5, 12, 49, 28));
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expect(
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iso,
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matches(r'^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}.*[+-]\d{2}:\d{2}$'),
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reason: 'without an offset the receiver has to guess, and guesses UTC',
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);
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});
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test('round-trips back to the same instant', () {
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// The whole point. The old form parsed to a different moment than the one
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// the cashier rang the bill at.
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final rung = DateTime(2026, 8, 5, 12, 49, 28, 245);
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final parsed = DateTime.parse(Formatters.isoWithOffset(rung));
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expect(
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parsed.toUtc(),
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rung.toUtc(),
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reason: 'the instant must survive the trip to the back office',
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);
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});
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test('keeps the wall clock the till actually showed', () {
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// Load-bearing for businessdate. The back office derives a day's takings
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// from the wall clock, so a bill rung at 12:49 must still read 12:49 —
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// converting to UTC before sending would have moved it to 07:19 and put
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// late-evening sales on the previous day.
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final iso = Formatters.isoWithOffset(DateTime(2026, 8, 5, 12, 49, 28));
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expect(iso, startsWith('2026-08-05T12:49:28'));
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});
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test('does not drop a half-hour offset', () {
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// India is +05:30. An implementation that formatted only whole hours
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// would produce +05:00 here and be wrong by thirty minutes — the kind of
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// error that survives review because it looks almost right.
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final offset = DateTime.now().timeZoneOffset;
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final iso = Formatters.isoWithOffset(DateTime(2026, 8, 5, 12, 0));
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final minutes = offset.abs().inMinutes % 60;
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expect(
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iso.substring(iso.length - 2),
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minutes.toString().padLeft(2, '0'),
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reason: 'the minutes component must come from the real offset',
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);
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});
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test('a UTC input is converted, not relabelled', () {
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// Passing an already-UTC DateTime must not stamp it with the local
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// offset while leaving the UTC wall clock in place — that would recreate
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// the original bug in reverse.
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final instant = DateTime.utc(2026, 8, 5, 7, 19, 28);
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final parsed = DateTime.parse(Formatters.isoWithOffset(instant));
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expect(parsed.toUtc(), instant);
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});
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});
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}
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