Feature: Update the tests to support the Microsoft Testing Platform and update the Unit Test Mode Detector

[glennawatson]

This pull request introduces support for the Microsoft Testing Platform (MTP) as a test runner, updates several test dependencies, and ensures the codebase and tests are compatible with the latest tooling. The most important changes are grouped below:

Microsoft Testing Platform (MTP) Integration:

• Added configuration and property settings to enable the Microsoft Testing Platform and its code coverage extension in test projects, including a new testconfig.json for parallel execution and coverage settings (src/Directory.Build.props, src/testconfig.json, [1] [2].
• Added a global configuration file specifying MTP as the test runner (src/global.json, src/global.jsonR1-R5).

Dependency and Package Updates:

• Upgraded key dependencies to their latest versions, including Microsoft.Extensions.DependencyInjection, Microsoft.Extensions.Logging, and NUnit3TestAdapter. Added new packages for MTP support and code coverage (src/Directory.Packages.props, [1] [2].
• Improved handling of framework-specific package versions, especially for System.Runtime.Serialization.Formatters, to ensure compatibility across different target frameworks (src/Directory.Packages.props, [1] [2].

Test and Detection Enhancements:

• Updated the DefaultModeDetector to recognize MTP assemblies, improving the ability to detect when tests are running under MTP (src/Splat/ModeDetection/DefaultModeDetector.cs, src/Splat/ModeDetection/DefaultModeDetector.csR38).
• Added new unit tests to verify that the mode detector correctly identifies the Microsoft Testing Platform as a test runner (src/Splat.Tests/ModeDetection/DefaultModeDetectorTests.cs, src/Splat.Tests/ModeDetection/DefaultModeDetectorTests.csR251-R305).

[Copilot]

Pull request overview

This pull request adds support for the Microsoft Testing Platform (MTP) as a test runner alongside the existing NUnit framework. The changes include configuration files for MTP, updates to test detection logic, new unit tests, and significant dependency version upgrades.

• Adds MTP configuration via testconfig.json and global.json for parallel test execution and code coverage
• Updates DefaultModeDetector to recognize MTP assemblies as test runners
• Upgrades multiple packages to version 10.0.1 and 18.x versions

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/testconfig.json	Configures MTP parallel execution and code coverage settings with module path filters
src/global.json	Specifies Microsoft Testing Platform as the test runner
src/Splat/ModeDetection/DefaultModeDetector.cs	Adds "MICROSOFT.TESTING.PLATFORM" to the list of recognized test framework markers
src/Splat.Tests/ModeDetection/DefaultModeDetectorTests.cs	Adds two new tests to verify MTP detection functionality
src/Directory.Packages.props	Updates package versions including Microsoft.Extensions packages, test SDK, and introduces framework-specific versioning logic for System.Runtime.Serialization.Formatters
src/Directory.Build.props	Configures MTP support properties and adds testconfig.json to test projects with code coverage package reference

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[codecov]

Codecov Report

❌ Patch coverage is 2.56410% with 38 lines in your changes missing coverage. Please review.
✅ Project coverage is 41.29%. Comparing base (2bc1a8c) to head (78c8223).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...at.Tests/ModeDetection/DefaultModeDetectorTests.cs	0.00%	38 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1454       +/-   ##
===========================================
- Coverage   73.27%   41.29%   -31.99%     
===========================================
  Files         108      149       +41     
  Lines        4345     7822     +3477     
  Branches      617      844      +227     
===========================================
+ Hits         3184     3230       +46     
- Misses        963     4408     +3445     
+ Partials      198      184       -14     

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[github-actions]

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