测试基于任务的WCF调用

Question

I am converting the WCF calls I am making in an application to run asynchronously to ensure the GUI is responsive while it gets data. Mostly I am using these methods to populate the properties of a ViewModel.

For instance, here's my old and new code:

private async Task LoadDataItems()
{
    //DataItems = Service.SelectDataItems();

    DataItems = await Service.SelectDataItemsAsync();
}

Also, here's some test code using RhinoMocks:

//Doesn't set DataItems when LoadDataItems() is called
myWcfServiceClient.Stub(async client => await client.SelectDataItemsAsync()).Return(new Task<List<DataItemDto>>(() => new List<DataItemDto> { testDataItem }));

//NullReferenceException on SelectDataItemsAsync()
myWcfServiceClient.Stub(client => client.SelectDataItemsAsync().Result).Return(new List<DataItemDto> { testDataItem });

Basically, in my unit test, either DataItems isn't set or I get a NullReferenceException trying to fake out the result. This is probably as much a question on RhinoMocks than anything...

Answer 1

In RhinoMocks, you define the Result on the Task-based operation with Task.FromResult(...)

So, my test code would set up the result as follows:

myWcfServiceClient.Stub(client => client.SelectDataItemsAsync()).Return(Task.FromResult(new List<DataItemDto> { testDataItem }));

Simple and works great!