ComplexBusinessOperations-1.cs

Awaiter.cs

public class Awaiter
{
    private readonly MyPrimitiveSynchronisationContext syncContext;

    internal Awaiter(MyPrimitiveSynchronisationContext syncContext)
    {
        this.syncContext = syncContext;
    }

    public void WaitFor(IAsyncResult toWaitOn)
    {
        WaitFor(() => toWaitOn.IsCompleted);      
    }
    // Our new wait method which can wait for anything
    // Continues when the condition is true
    public void WaitFor(Func<bool> toWaitOn)
    {
        while (!toWaitOn())
        {
            syncContext.RunOneRound();
        }
    }
}

ComplexBusinessOperations-1.cs

public event Action GoodsArrived;

public void SendGoodsToCostumers(string theGoods)
{
    var package = PreparePackage(theGoods);
    SendPackage(package);
    GoodsArrived();
}

private string SendPackage(string package)
{
    // This operation takes a while
    Thread.Sleep(50);
    return "Send: " + package;
            
}

private string PreparePackage(string theGoods)
{
    // This operation takes a while
    Thread.Sleep(50);
    return "Wrapped: " + theGoods;
}

ComplexBusinessOperations-2.cs

public event Action GoodsArrived;

public async void SendGoodsToCostumersAsync(string theGoods)
{
    var package = await PreparePackageAsync(theGoods);
    var sentPackage = await SendPackageAsync(package);
    GoodsArrived();
}

private Task<string> SendPackageAsync(string package)
{
    // Remember, this is just a simulation
    // Usually you would use some other async API here
    return TaskEx.Run(() =>
                            {
                                // This operation takes a while
                                Thread.Sleep(50);
                                return "Send: " + package;
                            });
}

private Task<string> PreparePackageAsync(string theGoods)
{
    // Remember, this is just a simulation
    // Usually you would use some other async API here
    return TaskEx.Run(() =>
                            {
                                // This operation takes a while
                                Thread.Sleep(50);
                                return "Wrapped:: " + theGoods;
                            });
}

ComplexBusinessOperations-3.cs

// Return a Taks instead of void to make testing easier
public async Task SendGoodsToCostumersAsync(string theGoods)
{
    var package = await PreparePackageAsync(theGoods);
    var sentPackage = await SendPackageAsync(package);
    GoodsArrived();
}

ComplexBusinessOperationsTest-1.cs

[Test]
public void SendGoodsToCostumers()
{
    var toTest = new ComplexBusinessOperations();

    var wasSent = false;
    toTest.GoodsArrived += () => wasSent = true;
    toTest.SendGoodsToCostumers("A Nice Toy");
    Assert.IsTrue(wasSent);
}

ComplexBusinessOperationsTest-2.cs

[Test]
public void SendGoodsToCostumers()
{
    var toTest = new ComplexBusinessOperations();

    var wasSent = false;
    toTest.GoodsArrived += () => wasSent = true;
    toTest.SendGoodsToCostumersAsync("A Nice Toy").Wait();
    Assert.IsTrue(wasSent);
}

ComplexBusinessOperationsTest-3.cs

[Test]
public void SendGoodsToCostumers()
{
    TestSyncContext.Run((awaiter)=>
    {
        var toTest = new ComplexBusinessOperations();

        var wasSent = false;
        toTest.GoodsArrived += () => wasSent = true;
        toTest.SendGoodsToCostumersAsync("A Nice Toy");
        awaiter.WaitFor(()=>wasSent);
        Assert.IsTrue(wasSent);
                                
    });
}