我创建了一些示例 ViewModel 来测试 DP 与 asyncCtp 的使用情况:
public class SampleVm : DependencyObject
{
public static readonly DependencyProperty SampleDependencyPropertyProperty =
DependencyProperty.Register("SampleDependencyProperty", typeof (int), typeof (SampleVm), new PropertyMetadata(default(int)));
public int SampleDependencyProperty
{
get { return (int) GetValue(SampleDependencyPropertyProperty); }
set { SetValue(SampleDependencyPropertyProperty, value); }
}
public ISampleModel _model;
public SampleVm(ISampleModel model)
{
_model = model;
}
public async Task SetDependencyProperty()
{
var modelData = await TaskEx.Run(() => _model.GetSomeIntegerValue());
SampleDependencyProperty = modelData;
}
}
注入 ViewModel 的模型是:
public interface ISampleModel
{
int GetSomeIntegerValue();
}
public class SampleModel : ISampleModel
{
public int GetSomeIntegerValue()
{
return 10;
}
}
当我运行 WPF 应用程序时没有问题,但是当我想使用以下代码对其进行测试时:
[Fact]
public async Task CheckValueSetting()
{
var model = new Mock<ISampleModel>();
model.Setup(x => x.GetSomeIntegerValue()).Returns(5);
var viewModel =new SampleVm(model.Object);
await viewModel.SetDependencyProperty();
Assert.Equal(5, viewModel.SampleDependencyProperty);
}
我收到以下错误:
System.InvalidOperationException: The calling thread cannot access this object because a different thread owns it.
Server stack trace:
at System.Windows.Threading.Dispatcher.VerifyAccess()
at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value)
at WpfApplication4.SampleVm.set_SampleDependencyProperty(Int32 value) in SampleVM.cs: line 19
at WpfApplication4.SampleVm.<SetDependencyProperty>d__1.MoveNext() in SampleVM.cs: line 30
Exception rethrown at [0]:
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
at WpfApplication4.SampleVmFixture.<CheckValueSetting>d__0.MoveNext() in SampleVmFixture.cs: line 16
那么解决方案是什么?