[6.1] Add Stress Tests to CI

[paulmedynski]

Description

Port of 3 PRs from main: #3546, #3548. #3558.

Adding stress tests runs to CI. These will use 1ES images for Windows and Linux, and Azure Pipelines macos-latest for macOS. All tests run against a locally installed SQL Server using SQL auth.

CI pipelines disable stress tests by default. You can manually run the pipelines with stress tests enabled.

[Copilot]

Pull Request Overview

The PR adds stress tests to CI by porting three PRs from main branch (#3546, #3548, #3558). It introduces a comprehensive stress testing framework that can run against locally installed SQL Server using SQL authentication. The stress tests are disabled by default in CI pipelines but can be manually enabled.

Key changes include:

• Addition of a complete stress testing framework with multiple projects
• Configuration system supporting both XML and JSON config files
• Test runners with various execution modes (stress, multithreaded, thread pool)
• SQL Server specific test implementations covering async operations, MARS, XML handling, and streaming

Reviewed Changes

Copilot reviewed 69 out of 69 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
tools/targets/GenerateThisAssemblyCs.targets	Adds NuGetPackageVersion constant for version tracking
src/Microsoft.Data.SqlClient/tests/StressTests/StressTests.slnx	Solution file defining stress test project structure
src/Microsoft.Data.SqlClient/tests/StressTests/SqlClient.Stress.Tests/*	Main test implementations for SqlClient stress scenarios
src/Microsoft.Data.SqlClient/tests/StressTests/SqlClient.Stress.Runner/*	Test execution engine and harness infrastructure
src/Microsoft.Data.SqlClient/tests/StressTests/SqlClient.Stress.Framework/*	Core framework classes and utilities
src/Microsoft.Data.SqlClient/tests/StressTests/SqlClient.Stress.Common/*	Common attributes and base classes

Comments suppressed due to low confidence (1)

src/Microsoft.Data.SqlClient/tests/StressTests/SqlClient.Stress.Tests/SqlClientTestGroup.cs:278

• The method documentation comment is incomplete. It should describe the parameters, return value, and what the method does beyond just 'Utility function used by async tests'.

        /// <summary>

---

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[paulmedynski]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.64%. Comparing base (7a7b54e) to head (cf441ee).
⚠️ Report is 8 commits behind head on release/6.1.

Additional details and impacted files

@@               Coverage Diff               @@
##           release/6.1    #3565      +/-   ##
===============================================
- Coverage        69.69%   64.64%   -5.05%     
===============================================
  Files              281      279       -2     
  Lines            62413    61748     -665     
===============================================
- Hits             43500    39920    -3580     
- Misses           18913    21828    +2915     

Flag	Coverage Δ
addons	90.82% <ø> (ø)
netcore	67.06% <ø> (-5.70%)	⬇️
netfx	68.08% <ø> (-1.16%)	⬇️

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[paulmedynski]

The latest CI-SqlClient run for this PR is all green:
https://sqlclientdrivers.visualstudio.com/public/_build/results?buildId=122987&view=results
GitHub is confused and reporting unrelated status from a manual run of CI from this branch.

This PR can be merged once approved.