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Code Analyzer for C#

There is a newer version: 10.2.0.105762

Why is this an issue?
Using Thread.Sleep in a test might introduce unpredictable and inconsistent results depending on the environment. Furthermore, it will
block the thread, which means the system resources are not being fully used.
[TestMethod]
public void SomeTest()
{
    Thread.Sleep(500); // Noncompliant
    // assertions...
}

An alternative is a task-based asynchronous approach, using async and await.
More specifically the Task.Delay method should be
used, because of the following advantages:

   It is asynchronous: The thread will not be blocked, but instead will be reused by other operations 
   It is more precise in timing the delay than Thread.Sleep 
   It can be canceled and continued, which gives more flexibility and control in the timing of your code 

[TestMethod]
public async Task SomeTest()
{
    await Task.Delay(500);
    // assertions...
}

Another scenario is when some data might need to be mocked using Moq, and a delay needs to be
introduced:
[TestMethod]
public void UserService_Test()
{
    var userService = new Mock<UserService>();
    var expected = new User();

    userService
        .Setup(m => m.GetUserById(42))
        .Returns(() =>
        {
            Thread.Sleep(500); // Noncompliant
            return Task.FromResult(expected);
        });

    // assertions...
}

An alternative to Thread.Sleep while mocking with Moq is to use ReturnsAsync and pass the amount of time to
delay there:
[TestMethod]
public void UserService_Test()
{
    var userService = new Mock<UserService>();
    var expected = new User();

    userService
        .Setup(m => m.GetUserById(42))
        .ReturnsAsync(expected, TimeSpan.FromMilliseconds(500));

    // assertions...
}

Resources
Documentation

   Thread.Sleep method 
   Task.Delay method 
   Asynchronous programming with async and await 
   Moq mocking library