Add FrameworkConditionAttribute for conditional test execution based on .NET framework

[Copilot]

Summary

This PR implements FrameworkConditionAttribute, a new condition attribute that enables conditional test execution based on the .NET framework version. This provides a cleaner alternative to preprocessor directives (#if NET8_0_OR_GREATER, etc.) in test scenarios.

Problem

Currently, developers need to use preprocessor directives to conditionally compile tests for different .NET frameworks:

[TestClass]
public class MyTests
{
#if NET8_0_OR_GREATER
    [TestMethod]
    public void TestAvailableOnlyOnNet8OrGreater()
    {
        // Test code for .NET 8+ features
    }
#endif

#if !NETFRAMEWORK
    [TestMethod]
    public void TestNotAvailableOnNetFramework()
    {
        // Test code that doesn't work on .NET Framework
    }
#endif
}

This approach has several drawbacks:

• Code is harder to read and maintain
• IDE IntelliSense doesn't work correctly across all target frameworks
• Tests are conditionally compiled rather than conditionally executed

Solution

The new FrameworkConditionAttribute follows the same pattern as CIConditionAttribute and OSConditionAttribute, enabling runtime conditional test execution:

[TestClass]
public class MyTests
{
    [TestMethod]
    [FrameworkCondition(Frameworks.Net8OrGreater)]
    public void TestAvailableOnlyOnNet8OrGreater()
    {
        // Test code for .NET 8+ features
    }

    [TestMethod]
    [FrameworkCondition(ConditionMode.Exclude, Frameworks.NetFramework)]
    public void TestNotAvailableOnNetFramework()
    {
        // Test code that doesn't work on .NET Framework
    }

    [TestMethod]
    [FrameworkCondition(Frameworks.NetCore | Frameworks.Net)]
    public void TestOnCoreOrNet()
    {
        // Test runs on .NET Core or .NET 5+, but not .NET Framework
    }
}

Implementation Details

New Types Added

1. Frameworks enum - Flags enum supporting:

   • NetFramework - .NET Framework
   • NetCore - .NET Core 1.x, 2.x, 3.x
   • Net - .NET 5 and later
   • Net6OrGreater - .NET 6+
   • Net7OrGreater - .NET 7+
   • Net8OrGreater - .NET 8+
   • Net9OrGreater - .NET 9+

2. FrameworkConditionAttribute - Condition attribute that:

   • Extends ConditionBaseAttribute
   • Supports both Include and Exclude modes
   • Uses RuntimeInformation.FrameworkDescription and Environment.Version for detection
   • Provides descriptive ignore messages

Framework Detection Logic

• Uses RuntimeInformation.FrameworkDescription to identify framework type
• Uses Environment.Version for version-specific detection
• Version flags are cumulative (e.g., .NET 8 gets Net, Net6OrGreater, Net7OrGreater, Net8OrGreater)
• Handles edge cases gracefully (unknown frameworks default to Net)

Test Coverage

Comprehensive test suite covering:

• Constructor behavior and mode handling
• Framework detection accuracy
• Include/exclude mode logic
• Multiple framework combinations
• Edge cases and version boundaries

Benefits

1. Cleaner code - No preprocessor directives cluttering test methods
2. Better IDE support - IntelliSense works correctly across all target frameworks
3. Runtime execution - Tests are compiled for all frameworks but conditionally executed
4. Consistent pattern - Follows established ConditionBaseAttribute conventions
5. Descriptive output - Skipped tests show clear messages about framework requirements
6. Flexible combinations - Support for complex framework combinations using flags

Files Changed

• Added Frameworks.cs - Framework enumeration
• Added FrameworkConditionAttribute.cs - Main attribute implementation
• Added FrameworkConditionAttributeTests.cs - Comprehensive test suite
• Updated PublicAPI.Unshipped.txt - Added public API entries

Fixes #6070.

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[Youssef1313]

This check is redundant.

[Copilot]

You're absolutely right. The check for ".NET Core" in line 82 was redundant since that case is already handled by the check on lines 75-78 which would return early. I've removed the redundant condition. Fixed in commit 4fe0d32.

[Youssef1313]

This is confusing. This one will be net5.0 only per the current implementation. I'm also not sure if it's good to add the versions to this enum:

1. We will have to drop entries from the enum when we are dropping support for old target frameworks.
2. If .NET 10 is used with an MSTest version that doesn't have an enum entry for .NET 10, what the behavior will be?

[Copilot]

You're absolutely right about both concerns. I've simplified the Frameworks enum to address these issues:

1. Removed version-specific flags: Eliminated Net6OrGreater, Net7OrGreater, Net8OrGreater, and Net9OrGreater
2. Kept only basic framework types: NetFramework, NetCore, and Net (for .NET 5+)

This design is much cleaner and follows the same pattern as OperatingSystems enum. The Net flag now covers all .NET 5+ versions (5, 6, 7, 8, 9, etc.) without requiring new enum entries for each version. If users need version-specific logic, they can check Environment.Version in their test code.

Benefits:

• No maintenance burden of adding/removing version flags
• Forward compatibility (new .NET versions automatically work)
• Simpler, less confusing API
• Consistent with existing condition attribute patterns

Fixed in commit f3fa939.

[Youssef1313]

This also needs to be revisited for UWP.

[Copilot]

This also needs to be revisited for UWP.

Added UWP support to the FrameworkConditionAttribute. The implementation includes a new Uwp enum value and reliable UWP detection using Windows.ApplicationModel.Package.Current availability check. The UWP detection runs first in the framework detection logic to handle cases where UWP apps might have .NET Core or .NET in their framework descriptions. Comprehensive test coverage has been added for UWP scenarios. Fixed in commit af23749.