public void SwitchOffMainThreadAsync_CanceledBeforeSwitch()
{
using (CancellationTokenSource cts = new CancellationTokenSource())
{
cts.Cancel();
try
{
AsynchronityUtilities.SwitchOffMainThreadAsync(cts.Token);
Assert.Fail("Expected OperationCanceledException not thrown.");
}
catch (OperationCanceledException ex)
{
Assert.AreEqual(cts.Token, ex.CancellationToken);
}
}
}
public void SwitchOffMainThreadAsync_CanceledMidSwitch()
{
using (CancellationTokenSource cts = new CancellationTokenSource())
{
AsynchronityUtilities.TaskSchedulerAwaiter awaitable = AsynchronityUtilities.SwitchOffMainThreadAsync(cts.Token);
AsynchronityUtilities.TaskSchedulerAwaiter awaiter = awaitable.GetAwaiter();
cts.Cancel();
try
{
awaiter.GetResult();
Assert.Fail("Expected OperationCanceledException not thrown.");
}
catch (OperationCanceledException ex)
{
Assert.AreEqual(cts.Token, ex.CancellationToken);
}
}
}
public async Task SwitchOffMainThreadAsync_OnMainThread()
{
// Make this thread look like the main thread by
// setting up a synchronization context.
SynchronizationContext dispatcher = new SynchronizationContext();
SynchronizationContext original = SynchronizationContext.Current;
SynchronizationContext.SetSynchronizationContext(dispatcher);
try
{
Thread originalThread = Thread.CurrentThread;
await AsynchronityUtilities.SwitchOffMainThreadAsync(CancellationToken.None);
Assert.AreNotSame(originalThread, Thread.CurrentThread);
Assert.IsNull(SynchronizationContext.Current);
}
finally
{
SynchronizationContext.SetSynchronizationContext(original);
}
}
public void SwitchOffMainThreadAsync_OffMainThread()
{
AsynchronityUtilities.TaskSchedulerAwaiter awaitable = AsynchronityUtilities.SwitchOffMainThreadAsync(CancellationToken.None);
AsynchronityUtilities.TaskSchedulerAwaiter awaiter = awaitable.GetAwaiter();
Assert.IsTrue(awaiter.IsCompleted); // guarantees the caller wouldn't have switched threads.
}