Ensure NotInParallel tests don't run alongside any others

[thomhurst]

Fixes #3001

[claude]

Claude finished @thomhurst's task —— View job

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PR Review Analysis

Reviewing PR #3015: "Ensure NotInParallel tests don't run alongside any others"

Todo List

• Read the modified TestScheduler.cs file to understand changes
• Analyze code quality and best practices
• Check for potential bugs or issues
• Evaluate performance considerations
• Review security concerns
• Assess test coverage implications
• Provide comprehensive feedback

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Review Feedback

✅ Code Quality & Best Practices

• Clean implementation: The change is minimal and focused, changing only the execution flow without modifying complex logic
• Consistent style: Follows existing code patterns and maintains proper async/await usage
• Good separation of concerns: The change doesn't break the existing architecture

✅ Bug Fix Analysis

The core change addresses a critical scheduling issue:

Problem Fixed: Global NotInParallel tests were previously running concurrently with other test groups, violating their constraint contract.

Before (TestScheduler.cs:175-180):

var globalNotInParallelTask = ExecuteNotInParallelTestsAsync(...);
allTestTasks.Add(globalNotInParallelTask); // ❌ Runs with other groups

After:

await ExecuteNotInParallelTestsAsync(...); // ✅ Runs sequentially first

Impact: This ensures NotInParallel tests truly run in isolation, which is critical for tests that require exclusive access to shared resources.

✅ Performance Considerations

• Potential slower execution: Global NotInParallel tests now block all other test execution, which may increase total test suite runtime
• Correctness over speed: This is the correct trade-off - TUnit's reliability is more important than marginally faster execution
• Minimal overhead: The change doesn't introduce additional allocations or complex logic
• Keyed NotInParallel tests still optimized: These continue to run in parallel with other groups where possible

✅ Security Concerns

• No security implications: This is a scheduling change with no exposure to external inputs or data handling
• Resource isolation improved: Better isolation of NotInParallel tests reduces potential resource contention issues

⚠️ Test Coverage Considerations

• Missing test validation: The PR doesn't include tests to verify the new behavior
• Regression risk: Without tests, future changes might accidentally reintroduce concurrent execution of NotInParallel tests
• Recommendation: Add integration tests that verify:
  1. Global NotInParallel tests complete before any other tests start
  2. Test execution order is preserved
  3. Keyed NotInParallel tests still work correctly

Minor Issues

• Whitespace changes: The PR includes some trailing whitespace cleanup (lines 321, 331, 340, 357, 367, 372) - good housekeeping but unrelated to the fix
• No breaking changes: The API surface remains unchanged

Overall Assessment: ✅ APPROVED

This is a correct and necessary fix for a critical scheduling bug. The implementation is clean, minimal, and follows TUnit's architectural patterns. While it may slightly impact performance, ensuring test isolation is paramount for test framework reliability.

Recommendations for follow-up:

1. Add integration tests to verify the fix
2. Consider documenting the execution order in comments or docs
3. Monitor test suite performance impact in CI

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