public void AsyncLazy_CompletesOnThreadWithValueFactory(NamedSyncContexts invokeOn, NamedSyncContexts completeOn)
{
// Set up various SynchronizationContexts that we may invoke or complete the async method with.
var aSyncContext = SingleThreadedSynchronizationContext.New();
var bSyncContext = SingleThreadedSynchronizationContext.New();
var invokeOnSyncContext = invokeOn == NamedSyncContexts.None ? null
: invokeOn == NamedSyncContexts.A ? aSyncContext
: invokeOn == NamedSyncContexts.B ? bSyncContext
: throw new ArgumentOutOfRangeException(nameof(invokeOn));
var completeOnSyncContext = completeOn == NamedSyncContexts.None ? null
: completeOn == NamedSyncContexts.A ? aSyncContext
: completeOn == NamedSyncContexts.B ? bSyncContext
: throw new ArgumentOutOfRangeException(nameof(completeOn));
// Set up a single-threaded SynchronizationContext that we'll invoke the async method within.
SynchronizationContext.SetSynchronizationContext(invokeOnSyncContext);
var unblockAsyncMethod = new TaskCompletionSource <bool>();
var getValueTask = new AsyncLazy <int>(async delegate
{
await unblockAsyncMethod.Task.ConfigureAwaitRunInline();
return(Environment.CurrentManagedThreadId);
}).GetValueAsync();
var verificationTask = getValueTask.ContinueWith(
lazyValue => Environment.CurrentManagedThreadId,
CancellationToken.None,
TaskContinuationOptions.ExecuteSynchronously,
TaskScheduler.Default);
SynchronizationContext.SetSynchronizationContext(completeOnSyncContext);
unblockAsyncMethod.SetResult(true);
// Confirm that setting the intermediate task allowed the async method to complete immediately, using our thread to do it.
Assert.True(verificationTask.IsCompleted);
Assert.Equal(Environment.CurrentManagedThreadId, verificationTask.Result);
}
