Add TestCategories property to ITestDataRow for per-test-case categorization

[Copilot]

This PR adds support for applying test categories to individual test data rows in parameterized tests, addressing a long-standing user request for more granular test categorization.

Changes

Core API Changes

• Added TestCategories property to ITestDataRow interface
• Implemented TestCategories property in TestDataRow<T> class with [DataMember] attribute
• Property is nullable to maintain backward compatibility

Discovery Logic Updates

• Updated TestDataSourceHelpers.TryHandleITestDataRow() to extract test categories from test data rows
• Added backward-compatible overload to maintain existing API
• Modified discovery logic in AssemblyEnumerator to merge test categories from test data rows with existing method/class/assembly level categories

Usage Example

[TestMethod]
[DynamicData(nameof(GetTestData), DynamicDataSourceType.Method)]
public void MyParameterizedTest(string input, string expected)
{
    Assert.AreEqual(expected, ProcessInput(input));
}

public static IEnumerable<object[]> GetTestData()
{
    // Fast unit test case
    yield return new TestDataRow<(string, string)>(("input1", "output1"))
    {
        TestCategories = new List<string> { "Unit", "Fast" },
        DisplayName = "Fast unit test"
    };
    
    // Slow integration test case
    yield return new TestDataRow<(string, string)>(("input2", "output2"))
    {
        TestCategories = new List<string> { "Integration", "Slow" },
        DisplayName = "Integration test"
    };
}

Benefits

• Granular filtering: Can now filter tests by categories applied to individual test cases
• Mixed scenarios: Single test method can contain both unit tests and integration tests with appropriate categories
• Category inheritance: Test data row categories are merged with method/class/assembly level categories
• Backward compatibility: Existing code continues to work unchanged

Test Coverage

• Added comprehensive unit tests for TestDataRow and TestDataSourceHelpers
• Added integration tests to verify end-to-end functionality
• Created sample test project demonstrating real-world usage
• Validated category filtering works correctly with test discovery

This enables scenarios like:

# Run only fast test cases
dotnet test --filter "TestCategory=Fast"

# Run only integration test cases  
dotnet test --filter "TestCategory=Integration"

Fixes #4089.

[!WARNING]

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

• 5rqvsblobprodcus385.vsblob.vsassets.io
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If you need me to access, download, or install something from one of these locations, you can either:

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---

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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:

• 5rqvsblobprodcus385.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.25316.2.txt (dns block)
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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
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[Youssef1313]

@copilot There is a merge conflict. Can you fix it?

[Copilot]

@copilot There is a merge conflict. Can you fix it?

The merge conflict in PublicAPI.Unshipped.txt has been resolved. I merged both the TestCategories property entries and the new Assert methods from main branch. (0ae57ea)

[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:

• 5rqvsblobprodcus385.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.25316.2.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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• Add the appropriate URLs or hosts to my firewall allow list

[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:

• 5rqvsblobprodcus385.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.25316.2.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

[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:

• ytvvsblobprodcus310.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.25352.1.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

[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:

• ytvvsblobprodcus310.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.25352.1.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

[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:

• ytvvsblobprodcus310.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.25352.1.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 66.66667% with 6 lines in your changes missing coverage. Please review.

Project coverage is 73.18%. Comparing base (591ca0a) to head (158ac3c). Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
....PlatformServices/Helpers/TestDataSourceHelpers.cs	44.44%	5 Missing :warning:
src/TestFramework/TestFramework/TestDataRow.cs	50.00%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5795      +/-   ##
==========================================
- Coverage   73.57%   73.18%   -0.40%     
==========================================
  Files         615      615              
  Lines       37639    38743    +1104     
==========================================
+ Hits        27693    28354     +661     
- Misses       9946    10389     +443     

Flag	Coverage Δ
Debug	73.18% <66.66%> (-0.40%)	:arrow_down:
integration	69.13% <57.14%> (-4.45%)	:arrow_down:
production	73.18% <66.66%> (-0.40%)	:arrow_down:
unit	73.56% <91.66%> (-0.01%)	:arrow_down:

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

Files with missing lines	Coverage Δ
...r.PlatformServices/Discovery/AssemblyEnumerator.cs	95.04% <100.00%> (-3.19%)	:arrow_down:
src/TestFramework/TestFramework/TestDataRow.cs	87.50% <50.00%> (-12.50%)	:arrow_down:
....PlatformServices/Helpers/TestDataSourceHelpers.cs	76.72% <44.44%> (-2.02%)	:arrow_down:

... and 34 files with indirect coverage changes

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