46 lines
1.8 KiB
Dart
46 lines
1.8 KiB
Dart
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/// Constant fixtures for the `Hlc` tests.
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///
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/// Nothing here reads the wall clock or generates a random value, because both
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/// make an HLC test depend on when it runs.
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///
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/// `Hlc.increment` and `Hlc.merge` compare against `clock.now()` and reject a
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/// timestamp that drifts more than a minute from it, so a fixture built from
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/// `DateTime.now()` only passes while the run is close to the moment the
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/// fixture was created. On a runner that re-executes tests in the same process
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/// that stops being true, since a top-level `final` is initialized once per
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/// isolate and can outlive the values derived from it.
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///
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/// Node ids are fixed for the same reason: `Hlc.compareTo` breaks ties on the
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/// node uuid, so a random id makes the expected ordering vary between runs.
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library;
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import 'package:clock/clock.dart';
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import 'package:uuid/uuid.dart';
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/// The instant the HLC tests treat as the current wall time.
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final hlcTime = DateTime.parse('2001-09-09T01:46:40.000Z');
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/// A node id that sorts before [hlcSecondNodeId].
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final hlcNodeId = UuidValue.withValidation(
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'11111111-1111-4111-8111-111111111111',
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);
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/// A node id that sorts after [hlcNodeId].
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final hlcSecondNodeId = UuidValue.withValidation(
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'22222222-2222-4222-8222-222222222222',
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);
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/// Runs [body] with the wall clock pinned to [wallTime].
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T atWallTime<T>(DateTime wallTime, T Function() body) =>
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withClock(Clock.fixed(wallTime), body);
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/// Offsets for building fixtures relative to [hlcTime].
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extension HlcFixtureTime on DateTime {
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/// This instant one millisecond later.
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DateTime advance([Duration duration = const Duration(milliseconds: 1)]) =>
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add(duration);
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/// This instant one millisecond earlier.
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DateTime retreat([Duration duration = const Duration(milliseconds: 1)]) =>
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subtract(duration);
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}
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