Fix MTP timeout parsing to use invariant culture instead of current culture

[Copilot]

The --timeout option parsing was using the current culture for float.TryParse(), which could cause parsing failures in locales that use different decimal separators (e.g., comma instead of period in German locale).

Changes Made

Fixed two locations where timeout values are parsed:

1. PlatformCommandLineProvider.cs - Validation logic now uses CultureInfo.InvariantCulture
2. TestHostBuilder.cs - Parsing logic now uses CultureInfo.InvariantCulture

Before

// This would fail in German locale for "1.5s"
float.TryParse(arg[..(size - 1)], out float value)

After

// This works consistently across all locales
float.TryParse(arg[..(size - 1)], CultureInfo.InvariantCulture, out float value)

Tests Added

Added comprehensive unit tests to verify:

• Valid timeout formats work across different cultures (en-US, de-DE, fr-FR)
• Invalid formats including culture-specific decimal separators are rejected
• Parsing specifically uses invariant culture vs current culture

The fix ensures that timeout values like --timeout 1.5s work consistently regardless of the user's system locale.

Fixes #5451.

---

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[Copilot]

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[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• 4vyvsblobprodcus361.vsblob.vsassets.io
  • Triggering command: dotnet build src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj --no-restore (dns block)
• 8xbvsblobprodcus382.vsblob.vsassets.io
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• bcnvsblobprodcus378.vsblob.vsassets.io
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• i1qvsblobprodcus353.vsblob.vsassets.io
  • Triggering command: dotnet build src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj --no-restore (dns block)
• l49vsblobprodcus358.vsblob.vsassets.io
  • Triggering command: dotnet build src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj --no-restore (dns block)
• mfjvsblobprodcus373.vsblob.vsassets.io
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  • Triggering command: dotnet build src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj --no-restore (dns block)

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[Copilot]

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[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• 4vyvsblobprodcus361.vsblob.vsassets.io
  • 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/10.0.0-beta.25305.3.txt (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

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[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• 4vyvsblobprodcus361.vsblob.vsassets.io
  • 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/10.0.0-beta.25305.3.txt (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 73.90%. Comparing base (1421741) to head (e69cb8c).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
...icrosoft.Testing.Platform/Hosts/TestHostBuilder.cs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5705      +/-   ##
==========================================
- Coverage   76.37%   73.90%   -2.48%     
==========================================
  Files         602      602              
  Lines       36664    36664              
==========================================
- Hits        28003    27095     -908     
- Misses       8661     9569     +908     

Flag	Coverage Δ
Debug	73.90% <50.00%> (-2.48%)	⬇️
integration	73.90% <50.00%> (-2.48%)	⬇️
production	73.90% <50.00%> (-2.48%)	⬇️
unit	73.90% <50.00%> (-2.48%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...latform/CommandLine/PlatformCommandLineProvider.cs	88.49% <100.00%> (-3.54%)	⬇️
...icrosoft.Testing.Platform/Hosts/TestHostBuilder.cs	91.42% <0.00%> (-3.35%)	⬇️

... and 59 files with indirect coverage changes

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