[release/10.0.4xx] Add dotnet test --results-directory-layout

[Evangelink]

Backport of #55475 to the .NET 10.0.4xx servicing branch.

When dotnet test runs a solution through Microsoft.Testing.Platform, all test applications currently share the same TestResults directory. Reports configured with the same relative filename can overwrite one another and silently lose results.

This adds:

dotnet test --results-directory-layout per-module

The per-module layout isolates each test application under:

<results-directory>/<project>/<target-framework>_<runtime>

The default remains flat, preserving existing behavior unless users opt in.

The implementation was adapted to the older MTP command architecture on release/10.0.4xx; no additional prerequisite backports are required.

Validation

• dotnet.Tests builds successfully.
• 20 targeted parser, resolver, and end-to-end tests pass.
• The full repository/redist build progressed through the changed CLI projects but remains blocked locally by unrelated native SDK layout prerequisites/file locking.

Fixes microsoft/testfx#10116.

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[Copilot]

Pull request overview

Backports dotnet test --results-directory-layout to the .NET 10.0.4xx servicing branch for the Microsoft.Testing.Platform (MTP) execution path, enabling an opt-in per-module results directory structure to prevent test report files from overwriting each other when multiple test applications run from a solution.

Changes:

• Adds --results-directory-layout <flat|per-module> to the MTP dotnet test command definition, help text, and localized resources.
• Introduces a TestResultsDirectoryResolver and threads it through the MTP execution pipeline so each test module can receive an isolated --results-directory.
• Adds unit + end-to-end coverage plus new test assets to validate overwrite behavior, per-module isolation, and same-project-name disambiguation.

Show a summary per file

File	Description
test/TestAssets/TestProjects/MultiTestProjectSolutionWithSharedReportName/TestProjectB/TestProjectB.csproj	Adds MTP test-asset project B used to reproduce shared report filename overwrites.
test/TestAssets/TestProjects/MultiTestProjectSolutionWithSharedReportName/TestProjectB/Program.cs	Writes a fixed relative report.txt into the MTP results directory to validate overwrite vs isolation.
test/TestAssets/TestProjects/MultiTestProjectSolutionWithSharedReportName/TestProjectA/TestProjectA.csproj	Adds MTP test-asset project A used to reproduce shared report filename overwrites.
test/TestAssets/TestProjects/MultiTestProjectSolutionWithSharedReportName/TestProjectA/Program.cs	Writes a fixed relative report.txt into the MTP results directory to validate overwrite vs isolation.
test/TestAssets/TestProjects/MultiTestProjectSolutionWithSharedReportName/MultiTestProjectSolutionWithSharedReportName.sln	Adds solution containing two MTP test apps for overwrite regression coverage.
test/TestAssets/TestProjects/MultiTestProjectSolutionWithSharedReportName/global.json	Forces MTP as the test runner for the new overwrite regression asset.
test/TestAssets/TestProjects/MultiTestProjectSolutionWithDuplicateProjectNames/src/Tests/Tests.csproj	Adds one of two same-named projects to validate per-module disambiguation.
test/TestAssets/TestProjects/MultiTestProjectSolutionWithDuplicateProjectNames/src/Tests/Program.cs	Writes a fixed relative report file to validate disambiguated per-module isolation.
test/TestAssets/TestProjects/MultiTestProjectSolutionWithDuplicateProjectNames/samples/Tests/Tests.csproj	Adds the second same-named project to validate per-module disambiguation.
test/TestAssets/TestProjects/MultiTestProjectSolutionWithDuplicateProjectNames/samples/Tests/Program.cs	Writes a fixed relative report file to validate disambiguated per-module isolation.
test/TestAssets/TestProjects/MultiTestProjectSolutionWithDuplicateProjectNames/MultiTestProjectSolutionWithDuplicateProjectNames.slnx	Adds a solution model containing two same-named projects in different folders.
test/TestAssets/TestProjects/MultiTestProjectSolutionWithDuplicateProjectNames/global.json	Forces MTP as the test runner for the duplicate-name disambiguation asset.
test/dotnet.Tests/CommandTests/Test/TestResultsDirectoryResolverTests.cs	Adds focused unit tests for flat vs per-module, pivot naming, disambiguation, and stability.
test/dotnet.Tests/CommandTests/Test/TestCommandParserTests.cs	Adds parser tests for --results-directory-layout defaulting/values and invalid-value rejection.
test/dotnet.Tests/CommandTests/Test/snapshots/MTPHelpSnapshotTests.VerifyMTPHelpOutput.verified.txt	Updates MTP help snapshot to include --results-directory-layout documentation.
test/dotnet.Tests/CommandTests/Test/GivenDotnetTestBuildsAndRunsTests.cs	Adds end-to-end coverage for per-module directory creation, overwrite regression, and disambiguation.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.zh-Hant.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.zh-Hans.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.tr.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.ru.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.pt-BR.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.pl.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.ko.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.ja.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.it.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.fr.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.es.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.de.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/xlf/CommandDefinitionStrings.cs.xlf	Adds localized string entries for the new option help/placeholder.
src/Cli/Microsoft.DotNet.Cli.Definitions/Commands/Test/TestCommandDefinition.MicrosoftTestingPlatform.cs	Introduces --results-directory-layout option and wires it into the MTP command options list.
src/Cli/Microsoft.DotNet.Cli.Definitions/CommandDefinitionStrings.resx	Adds resource strings for the new option help text and help-name placeholder.
src/Cli/dotnet/Commands/Test/MTP/TestResultsDirectoryResolver.cs	Implements per-module results directory computation, pivot naming, and name disambiguation hashing.
src/Cli/dotnet/Commands/Test/MTP/TestModulesFilterHandler.cs	Refactors to materialize/enumerate modules up front and enqueue after resolver construction.
src/Cli/dotnet/Commands/Test/MTP/TestApplicationActionQueue.cs	Threads a shared resolver into worker tasks and per-module TestApplication creation.
src/Cli/dotnet/Commands/Test/MTP/TestApplication.cs	Uses the resolver to supply the correct per-module --results-directory argument.
src/Cli/dotnet/Commands/Test/MTP/Options.cs	Adds ResultsDirectoryLayout and extends PathOptions to carry the selected layout policy.
src/Cli/dotnet/Commands/Test/MTP/MSBuildUtility.cs	Parses --results-directory-layout into PathOptions.ResultsDirectoryLayout.
src/Cli/dotnet/Commands/Test/MTP/MSBuildHandler.cs	Exposes EnumerateTestModules() so the full module set can be used to build the resolver.
src/Cli/dotnet/Commands/Test/MTP/MicrosoftTestingPlatformTestCommand.cs	Constructs the resolver from the complete module set and injects it into the action queue for both flows.

Copilot's findings

• Files reviewed: 39/39 changed files
• Comments generated: 0