dotnet-hosted-service-testing

Start the service, then account for the fact that StartAsync dispatches ExecuteAsync to a threadpool thread, so the first Advance is reliably lost. After each Advance, wait in real time for the Task.Delay continuation to land before asserting, and count loop invocations rather than side effects.

StartAsync returns before ExecuteAsync registers its Task.Delay timer on a threadpool thread, so an Advance issued immediately afterward fires before any timer exists and is silently lost. Sync on the service's own startup log event instead of advancing immediately.

No, AddHostedService<T> only registers IHostedService to T, so resolving T directly throws InvalidOperationException. Register the concrete type, the interface, and the hosted service as three singleton registrations resolving the same instance, and pin it with a reference-equality smoke test.

Derive the tick from the timeout, such as tick equals timeout divided by four, because a fixed 60-second tick makes short-timeout shutdown gates unsatisfiable. Pin the cadence with split Advances that stay below the deadline until the cadence is established, then cross it.

Parallel suite load can starve the real-time settle delays that fake-clock tests need after each Advance. Rebuild after test edits, since --no-build against a stale assembly reports phantom failures, then re-run under full-suite load before declaring the test flaky.