public void Cities_VerifyCustomHost()
        {
            CityDomainContext dp = new CityDomainContext(TestURIs.Cities);    // Abs URI so runs on desktop too

            InvokeOperation<bool> invokeOp = dp.UsesCustomHost(TestHelperMethods.DefaultOperationAction, null);

            EnqueueConditional(() => invokeOp.IsComplete);

            EnqueueCallback(() =>
            {
                if (invokeOp.Error != null)
                    Assert.Fail("InvokeOperation.Error: " + invokeOp.Error.Message);
                Assert.IsTrue(invokeOp.Value, "CityDomainService isn't using a custom host.");
            });

            EnqueueTestComplete();
        }