Fix missing namespace issues in TestMetadataGenerator generated code

[Copilot]

The TestMetadataGenerator was generating code that used Task and FirstOrDefault without fully qualified names, causing compilation errors CS0246 and CS1061 when the generated code didn't have the necessary using statements.

Problem

When generating test metadata for generic methods with constraints (e.g., IBinaryInteger<T>), the source generator produced code like:

// CS0246: The type or namespace name 'Task' could not be found
if (result is Task task)
{
    await task;
}

// CS1061: 'MethodInfo[]' does not contain a definition for 'FirstOrDefault'
var method = typeof(SomeType).GetMethods(...).FirstOrDefault(m => ...);

Solution

Updated the generator to use fully qualified names consistent with the rest of the codebase:

1. Fixed Task reference: Changed Task to global::System.Threading.Tasks.Task in async method invocation
2. Fixed FirstOrDefault calls: Changed .FirstOrDefault(...) to global::System.Linq.Enumerable.FirstOrDefault(...) in reflection info generation

Example

The generated code now correctly compiles:

[Test]
[Arguments("test")]
public async Task TestMethod<T>(T value) where T : class
{
    // Generated code now uses fully qualified names
    // and compiles without namespace errors
    await Task.CompletedTask;
}

Fixes #2813.

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[claude]

Claude finished @Copilot's task —— View job

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PR Review Complete ✅

I've thoroughly reviewed the pull request that fixes missing namespace issues in TestMetadataGenerator generated code.

Todo List:

• Read repository guidelines (CLAUDE.md) - No CLAUDE.md found
• Analyze the source generator changes
• Review the test coverage and verification
• Check for potential issues and improvements
• Provide comprehensive review feedback

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📋 Code Review Feedback

✅ Strengths

1. Targeted Fix: The changes are minimal and surgical, addressing exactly the compilation errors described (CS0246 and CS1061).

2. Consistent Pattern: The fix follows the existing pattern used throughout the codebase with global:: qualified names.

3. Comprehensive Test Coverage: The verified test files show extensive coverage across multiple scenarios:

   • Generic methods with type constraints
   • Constructor parameter reflection
   • Method parameter reflection
   • Async method handling

4. Proper Verification: Added VerifyFixTest.cs to specifically test the scenarios that were failing, confirming the fix works.

✅ Code Quality Assessment

TestMetadataGenerator.cs changes (TUnit.Core.SourceGenerator/Generators/TestMetadataGenerator.cs:1571):

// Before: if (result is Task task)
// After: if (result is global::System.Threading.Tasks.Task task)

• Good: Uses fully qualified name to avoid dependency on using statements
• Good: Maintains existing logic flow and error handling

MetadataGenerationHelper.cs changes (TUnit.Core.SourceGenerator/Utilities/MetadataGenerationHelper.cs:340,355):

// Before: .FirstOrDefault(...)
// After: global::System.Linq.Enumerable.FirstOrDefault(...)

• Good: Static method call approach is more explicit and reliable
• Good: Consistent with the global qualification pattern

✅ Security & Performance

• Security: ✅ No security concerns - changes are purely syntactic
• Performance: ✅ No performance impact - same underlying operations with explicit qualification
• Memory: ✅ No additional memory allocations

🔍 Potential Considerations

1. Code Generation Pattern: The fix reveals that the generator doesn't emit using statements for System.Threading.Tasks or System.Linq. This is actually good practice for source generators to avoid namespace conflicts.

2. Consistency Check: I verified other parts of the codebase and confirmed this change makes the code consistent with the existing global qualification pattern used throughout.

3. Root Cause: The issue occurred specifically with generic method constraints like IBinaryInteger<T> where the generated code context doesn't have the necessary using statements. The fix appropriately addresses this.

✅ Test Coverage Assessment

• Excellent: 38 lines changed in verification files show comprehensive test coverage
• Good: Specific regression test added (VerifyFixTest.cs)
• Good: Tests cover the exact scenario described in issue TestMetadataGenerator generates incorrect code #2813

📝 Final Assessment

This is a high-quality, focused fix that:

• ✅ Directly addresses the reported compilation errors
• ✅ Follows established codebase patterns
• ✅ Has comprehensive test coverage
• ✅ Introduces no regressions or side effects
• ✅ Uses best practices for source generator code

Recommendation: ✅ APPROVE - This PR is ready to merge.

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