Add analyzer to detect Thread.Sleep and Task.Wait in test methods

[Copilot]

Thread.Sleep() and Task.Wait() cause test flakiness when operations don't complete in fixed time windows. This analyzer detects these patterns at build time instead of via CodeQL, shifting feedback left.

Changes

• New analyzer: AvoidBlockingCallsInTestsAnalyzer (MSTEST0059)

  • Detects Thread.Sleep() and Task.Wait() invocations in test methods and fixtures
  • Reports as Warning (enabled by default, Category: Design)
  • Scopes to: TestMethod, DataTestMethod, TestInitialize/Cleanup, ClassInitialize/Cleanup, AssemblyInitialize/Cleanup
  • Ignores non-test helper methods

• Test coverage: 13 test cases covering all fixture types, positive/negative scenarios, and async alternatives

• Localization: Added resources for all 13 supported languages

Example

// Before - no warning
[TestMethod]
public void MyTest()
{
    Thread.Sleep(1000);
    task.Wait();
}

// After - warnings at build time
[TestMethod]
public void MyTest()
{
    Thread.Sleep(1000);  // MSTEST0059: Avoid using 'Thread.Sleep' in test methods
    task.Wait();         // MSTEST0059: Avoid using 'Task.Wait' in test methods
}

// Suggested fix
[TestMethod]
public async Task MyTest()
{
    await Task.Delay(1000);
    await task;
}

Warning

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  • Triggering command: dotnet build src/Analyzers/MSTest.Analyzers/MSTest.Analyzers.csproj --configuration Release (dns block)
  • Triggering command: /home/REDACTED/work/testfx/testfx/.dotnet/dotnet msbuild /m /nologo /clp:Summary /v:minimal /nr:true /warnaserror /p:TreatWarningsAsErrors=true /p:ContinuousIntegrationBuild=false /home/REDACTED/work/testfx/testfx/artifacts/toolset/restore.proj /t:__WriteToolsetLocation /clp:ErrorsOnly;NoSummary /p:__ToolsetLocationOutputFile=/home/REDACTED/work/testfx/testfx/artifacts/toolset/11.0.0-beta.25568.1.txt (dns block)
• rcxvsblobprodcus328.vsblob.vsassets.io
  • Triggering command: dotnet build src/Analyzers/MSTest.Analyzers/MSTest.Analyzers.csproj --configuration Release (dns block)

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>Detect Thread.Sleep(x) and Thread.Wait(x) inside test code to reduce flakiness</issue_title>
<issue_description>Detect Thread.Sleep(x) and Thread.Wait(x) inside test code to reduce flakiness

Background and Motivation

Thread.Sleep(x) and Thread.Wait(x) are causing test flakiness when operation is not completed in the specific time frame. In most of the cases asynchronous calls would be much better solution.

Proposed Feature

Detection of Thread.Sleep(x) and Thread.Wait(x) should be added for the test code so INFO or WARNING should inform developer during build time that there is possible flakiness in the test code.

Alternative Designs

Currently we are detecting above patterns using CodeQL inside the test code. Using test analyzer would be much better solution because it would shift the detection to the left (build time), speeding up detection and increasing quality.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Detect Thread.Sleep(x) and Thread.Wait(x) inside test code to reduce flakiness #6950

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[Youssef1313]

Should we be looking at Task.Delay instead?

[Youssef1313]

I don't think this name is accurate. It's not about blocking IMO. It's about arbitrary delays/sleeps.

[Youssef1313]

I wouldn't put as Warning by default. That's too aggressive IMO.
It should be Info. And not even sure if should be enabled by default or not.