我有一个带有异步任务的viewModel。我不知道如何对其进行测试。
public class MyViewModel : BindableBase
{
public MyViewModel()
{
this.PropertyChanged += MyViewModel_PropertyChanged;
}
private void MyViewModel_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
Action action = async () => await DoSomething();
action();
}
public const string BeforeKey = "before";
public const string AfterKey = "After";
public string Status { get; private set; } = BeforeKey;
public async Task DoSomething()
{
await Task.Delay(3000);
Status = AfterKey;
}
string bindagleProp;
public string BindagleProp
{
get { return bindagleProp; }
set { SetProperty(ref bindagleProp, value); }
}
}
这是我的测试内容:
[TestMethod]
public async Task TestMyViewModel()
{
MyViewModel viewModel = new MyViewModel();
Assert.AreEqual(viewModel.Status, MyViewModel.BeforeKey, "before check");
viewModel.BindagleProp = "abc";
Assert.AreEqual(viewModel.Status, MyViewModel.AfterKey, "after check");
}
测试失败是因为它没有等待任务完成。我不想在单元测试中使用Task.Delay,因为这不安全。DoSomething方法的持续时间可能是未知的。
谢谢您的任何帮助。
编辑:
实际上,这个问题不仅针对MVVM,而且针对任何异步事件处理程序。例如:
// class with some logic, can be UI or whatever.
public class MyClassA
{
Size size;
public Size Size
{
get { return size; }
set
{
size = value;
SizeChanged?.Invoke(this, EventArgs.Empty);
}
}
public event EventHandler SizeChanged;
}
// this class uses the MyClassA class.
public class MyCunsomerClass
{
readonly MyClassA myClassA = new MyClassA();
public MyCunsomerClass()
{
myClassA.SizeChanged += MyClassA_SizeChanged;
}
public string Status { get; private set; } = "BEFORE";
private async void MyClassA_SizeChanged(object sender, EventArgs e)
{
await LongRunningTaskAsync();
Status = "AFTER";
}
public async Task LongRunningTaskAsync()
{
await Task.Delay(3000);
///await XYZ....;
}
public void SetSize()
{
myClassA.Size = new Size(20, 30);
}
}
现在,我想要进行测试:
[TestMethod]
public void TestMyClass()
{
var cunsomerClass = new MyCunsomerClass();
cunsomerClass.SetSize();
Assert.AreEqual(cunsomerClass.Status, "AFTER");
}
测试失败了。