test(hardware): add comprehensive unit tests for NUMA distance relationships

[jra3]

Summary

This PR adds comprehensive unit tests for NUMA distance relationship creation to address issue #162. The implementation achieves 100% coverage for the previously untested createNUMADistanceRelationship function with 60+ test cases covering all NUMA topology scenarios found in production servers and cloud instances.

What Changed

New Test File

• internal/hardware/graph/numa_distance_test.go (646 lines)
  • 12 comprehensive test functions
  • 60+ individual test cases
  • Complete coverage of all NUMA patterns

Test Coverage by Phase

Phase 1: Basic Functionality Tests

• Basic Relationship Creation: Subject/object reference validation, successful creation
• Predicate Marshaling: Protobuf marshaling/unmarshaling of NUMAAffinity predicate
• Type Descriptor: Proper relationship type and kind validation
• Distance Preservation: Verify distance values are correctly stored

Phase 2: Distance Values & Validation

• Distance Value Range: Local (10), remote same-socket (20), remote cross-socket (40), zero, maximum (255), negative (-1)
• Nil Reference Handling: Nil source node, nil target node, both nil (no panics)
• Self-Referential: Node-to-itself relationships (typical local distance=10)
• Large Node IDs: Support for systems with many NUMA nodes (up to 255)
• Edge Cases: Zero distance, negative distance, very large distances

Phase 3: Real-World NUMA Topology Scenarios

• Dual-Socket Topology: Standard 2x2 distance matrix (Intel/AMD servers)
• Quad-Socket Topology: 4x4 distance matrix with multi-hop distances
• AMD EPYC Topology: Chiplet architecture (intra-socket=10-12, inter-socket=32)
• Intel Xeon Topology: Uniform cross-socket distances (typically 21)
• Eight-Socket Topology: Large server configurations with multi-hop distances
• Single-Node Systems: Cloud instances and small servers
• Cloud Provider Patterns: AWS c5.metal (2 nodes), GCP n2 (1 node), Azure L-series (4 nodes)
• Bidirectional Symmetry: Verify symmetric distance relationships
• Asymmetric Distances: Support for rare asymmetric NUMA configurations

Test Statistics

• 12 test functions covering all phases
• 60+ individual test cases for comprehensive coverage
• All NUMA architectures (Intel Xeon, AMD EPYC, cloud instances)
• All topology sizes (1, 2, 4, 8 NUMA nodes)
• Distance matrix validation for common server configurations

Coverage Achievement

createNUMADistanceRelationship Function:

• Before: 0% coverage (completely untested)
• After: 100% coverage ✅

Overall Package:

• Before: 70.9%
• After: 72.2%
• Improvement: +1.3 percentage points ✅

All tests passing:

ok  	github.com/antimetal/agent/internal/hardware/graph	13.844s	coverage: 72.2% of statements

Success Criteria Met

✅ Achieve 100% coverage for createNUMADistanceRelationship
✅ Test all NUMA distance scenarios
✅ Validate proper predicate creation
✅ Test error handling and edge cases
✅ Cover real-world NUMA topologies (Intel, AMD, cloud providers)

Testing

# Run all tests
go test ./internal/hardware/graph/...

# Run with coverage
go test ./internal/hardware/graph/... -cover

# Run specific NUMA distance tests
go test ./internal/hardware/graph/... -run "CreateNUMADistanceRelationship"

Closes #162

Related

• Closes test: Add unit tests for NUMA distance relationship creation #162
• Linear: https://linear.app/antimetal/issue/ENG-1766