Notifications

MockTimeSystem.On lets a test observe time-related events from the system under test, which is useful for asserting "the code asked to sleep for 5 seconds" without relying on side effects.

MockTimeSystem timeSystem = new();

using IAwaitableCallback<TimeSpan> sleeps = timeSystem.On.ThreadSleep();

new Gallery(timeSystem).CloseForTheNight(); // waits 5 seconds before switching off the lights

TimeSpan[] requestedSleeps = sleeps.Wait(count: 1);
await That(requestedSleeps[0]).IsEqualTo(TimeSpan.FromSeconds(5));

Like the file-system notifications, each method returns an IAwaitableCallback<T> you dispose to unsubscribe and Wait/WaitAsync to block until enough events arrive.

Available callbacks

Method on `On`	Fires when	`T`
`DateTimeRead()`	`DateTime.Now`, `UtcNow` or `Today` is read	`DateTime`
`DateTimeOffsetRead()`	`DateTimeOffset.Now` or `UtcNow` is read	`DateTimeOffset`
`TaskDelay()`	`Task.Delay` (any overload) is called	`TimeSpan`
`ThreadSleep()`	`Thread.Sleep` (any overload) is called	`TimeSpan`
`TimeChanged()`	the simulated time advanced (auto-advance or manual)	`DateTime`
`PeriodicTimer.WaitingForNextTick()`	a `PeriodicTimer` is waiting for its next tick (.NET 8 or later)	`IPeriodicTimer`

Each accepts an optional callback (run synchronously when the event fires) and an optional predicate to filter events before they are recorded.

// Only record sleeps longer than 1 second
using IAwaitableCallback<TimeSpan> longSleeps = timeSystem.On.ThreadSleep(
    predicate: ts => ts > TimeSpan.FromSeconds(1));

Available callbacks​

Available callbacks