Question

I have Visual Studio 2012 and an asynchronous test that needs a synchronization context.
But the default synchronization context of MSTest is null.
I would like to test as running on a WPF- or WinForms-UI thread that has a synchronization context.
What’s the best method to add a SynchronizationContext to the test thread ?

    [TestMethod]
    public async Task MyTest()
    {
        Assert.IsNotNull( SynchronizationContext.Current );
        await MyTestAsync();
        DoSomethingOnTheSameThread();
    }

Answer 1

Using the informations from Panagiotis Kanavos and Stephen Cleary, I can write my testmethods like this:

    [TestMethod]
    public void MyTest()
    {
      Helper.RunInWpfSyncContext( async () =>
      {
        Assert.IsNotNull( SynchronizationContext.Current );
        await MyTestAsync();
        DoSomethingOnTheSameThread();
      });
    }

The inner code now runs in a WPF synchronization context and handles all exceptions as used for MSTest.
The Helper method is from Stephen Toub:

using System.Windows.Threading; // WPF Dispatcher from assembly 'WindowsBase'

public static void RunInWpfSyncContext( Func<Task> function )
{
  if (function == null) throw new ArgumentNullException("function");
  var prevCtx = SynchronizationContext.Current;
  try
  {
    var syncCtx = new DispatcherSynchronizationContext();
    SynchronizationContext.SetSynchronizationContext(syncCtx);

    var task = function();
    if (task == null) throw new InvalidOperationException();

    var frame = new DispatcherFrame();
    var t2 = task.ContinueWith(x=>{frame.Continue = false;}, TaskScheduler.Default);
    Dispatcher.PushFrame(frame);   // execute all tasks until frame.Continue == false

    task.GetAwaiter().GetResult(); // rethrow exception when task has failed 
  }
  finally
  { 
    SynchronizationContext.SetSynchronizationContext(prevCtx);
  }
}