[Draft] Failing test

[Youssef1313]

DRAFT: Need to get to a state where a test fails on current main but passes with the fix in #52558

[Copilot]

Pull request overview

Adds a new test asset and an xUnit test intended to reproduce/guard against the dotnet test hang scenario described in #52558 (test app exits while a child process remains alive), plus a small test-framework tweak to optionally avoid stdout/stderr capture.

Changes:

• Add MTPChildProcessHangTest test project that spawns a “hanging” child process under Microsoft.Testing.Platform.
• Add a new DotnetTest_MTPChildProcessHangTestProject_ShouldNotHang test case for Debug/Release.
• Add DisableOutputAndErrorRedirection plumbing to the test command harness to optionally skip stdout/stderr capture.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
test/dotnet.Tests/CommandTests/Test/GivenDotnetTestBuildsAndRunsTests.cs	Adds a new test case that runs dotnet test against the new MTP asset.
test/TestAssets/TestProjects/MTPChildProcessHangTest/global.json	Forces the test runner to Microsoft.Testing.Platform for the asset.
test/TestAssets/TestProjects/MTPChildProcessHangTest/Program.cs	Implements a minimal MTP test app that spawns a child process intended to remain alive.
test/TestAssets/TestProjects/MTPChildProcessHangTest/MTPChildProcessHangTest.csproj	Defines the new test asset project and references Microsoft.Testing.Platform.
test/Microsoft.NET.TestFramework/Commands/TestCommand.cs	Adds an option to skip stdout/stderr capture and forwarding in the test harness.
test/Microsoft.NET.TestFramework/Commands/SdkCommandSpec.cs	Carries the new disable-redirection flag through the command spec.
src/Cli/dotnet/Commands/Test/MTP/TestApplication.cs	Encoding/first-line change only.

[Copilot]

The "hang" mode blocks indefinitely on a ManualResetEvent and the parent never cleans it up. If the dotnet test side stops hanging (or is killed by a timeout), this can leave an orphaned process running forever in CI. Make the child self-terminate after a bounded timeout (or implement explicit cleanup/kill logic) to avoid leaking processes.

[Youssef1313]

The active Test Run was aborted because the host process exited unexpectedly. Please inspect the call stack above, if available, to get more information about where the exception originated from.
The test running when the crash occurred: 
Microsoft.DotNet.Cli.Test.Tests.GivenDotnetTestBuildsAndRunsTests.DotnetTest_MTPChildProcessHangTestProject_ShouldNotHang