我已经完成了此单元测试,但我不明白为什么“ await Task.Delay()”不等待!
[TestMethod]
public async Task SimpleTest()
{
bool isOK = false;
Task myTask = new Task(async () =>
{
Console.WriteLine("Task.BeforeDelay");
await Task.Delay(1000);
Console.WriteLine("Task.AfterDelay");
isOK = true;
Console.WriteLine("Task.Ended");
});
Console.WriteLine("Main.BeforeStart");
myTask.Start();
Console.WriteLine("Main.AfterStart");
await myTask;
Console.WriteLine("Main.AfterAwait");
Assert.IsTrue(isOK, "OK");
}
这是单元测试输出:
这怎么可能不等待,而主线程继续?
new Task(async () =>
[任务不使用Func<Task>
,而是Action
。它将调用您的异步方法,并期望它在返回时结束。但事实并非如此。它返回一个任务。新任务不会等待该任务。对于新任务,一旦方法返回,作业就完成了。
您需要使用已经存在的任务,而不是将其包装在新任务中:
[TestMethod]
public async Task SimpleTest()
{
bool isOK = false;
Func<Task> asyncMethod = async () =>
{
Console.WriteLine("Task.BeforeDelay");
await Task.Delay(1000);
Console.WriteLine("Task.AfterDelay");
isOK = true;
Console.WriteLine("Task.Ended");
};
Console.WriteLine("Main.BeforeStart");
Task myTask = asyncMethod();
Console.WriteLine("Main.AfterStart");
await myTask;
Console.WriteLine("Main.AfterAwait");
Assert.IsTrue(isOK, "OK");
}
只需从task.delay(1000)中删除等待状态
[Fact]
public async Task SimpleTest()
{
bool isOK = false;
Task myTask = new Task(async () =>
{
Console.WriteLine("Task.BeforeDelay");
/////remove await
Task.Delay(1000);
Console.WriteLine("Task.AfterDelay");
isOK = true;
Console.WriteLine("Task.Ended");
});
Console.WriteLine("Main.BeforeStart");
myTask.Start();
Console.WriteLine("Main.AfterStart");
await myTask;
Console.WriteLine("Main.AfterAwait");
Assert.True(isOK, "OK");
}