test: comprehensive unit test suite for FUSION project

[ryanmccann1024]

Description:
This PR adds comprehensive unit test coverage across all FUSION modules, building on top of the refactor/module-cleanup branch. The test suite includes ~41,000 lines of new test code covering all major components, with corresponding fixes for type errors and edge cases discovered during testing.

🔧 Type of Change

Primary Change Type:

• 🧪 Tests - Adding missing tests or correcting existing tests
• 🐛 Bug Fix - Type error fixes and edge case handling discovered during testing
• 🔄 Refactor - Code improvements discovered during testing

Component(s) Affected:

• CLI Interface (fusion/cli/)
• Configuration System (fusion/configs/)
• Simulation Core (fusion/core/)
• ML/RL Modules (fusion/modules/rl/, fusion/modules/ml/)
• Routing Algorithms (fusion/modules/routing/)
• Spectrum Assignment (fusion/modules/spectrum/)
• SNR Calculations (fusion/modules/snr/)
• Unity/HPC Integration (fusion/unity/)
• Testing Framework (tests/)
• Analysis Module (fusion/analysis/)
• Reporting Module (fusion/reporting/)
• I/O Module (fusion/io/)
• Interfaces Module (fusion/interfaces/)
• Simulation Utils (fusion/sim/)
• General Utils (fusion/utils/)

🧪 Testing

Test Coverage:

• Unit tests added/updated
• Existing tests still pass
• Performance impact assessed

Test Details:

New Test Suites Added (19 commits):

1. Analysis Module (0cc3872) - 536 lines of tests for network analysis functionality
2. CLI Module (dadd35c) - 2,090 lines of tests covering command parsing, configuration setup, registry, and all run modes
3. Configs Module (d505c8f) - 2,389 lines of tests for configuration management, validation, schema, and registry
4. Core Module (574599f) - 4,461 lines of tests for simulation engine, metrics, persistence, routing, SNR, spectrum assignment
5. Interfaces Module (f77878e) - 3,092 lines of tests for agent, router, SNR, and spectrum interfaces with factory patterns
6. I/O Module (8c916ed) - 1,643 lines of tests for exporters, data generation, and structure handling
7. Reporting Module (080bb1c) - 622 lines of tests for simulation reporting functionality
8. Sim Module (aa8c1bc) - 2,034 lines of tests for network simulation, data utilities, formatting, I/O, and training pipeline
9. Sim Utils (3b652dc) - 2,462 lines of tests for simulation utilities with mypy fixes
10. Unity Module (81e8311) - 1,966 lines of tests for HPC integration (manifest creation, submission, results fetching)
11. General Utils (527fad8) - 2,599 lines of tests for config, data, logging, network, OS, random, and spectrum utilities
12. ML Module (bc432b3) - 1,897 lines of tests for feature engineering, preprocessing, evaluation, visualization, and model I/O
13. Routing Module (ea91e3f) - 2,801 lines of tests for routing algorithms with mypy/ruff fixes
14. SNR Module (3b69533) - 1,940 lines of tests for SNR calculations and utilities
15. Spectrum Module (7983e31) - 2,505 lines of tests for spectrum assignment algorithms
16. RL Module (de58efb) - 2,584 lines of tests for reinforcement learning components (algorithms, agents, environments, callbacks)

Type Error Fixes:

• RL & Interfaces (686c7f2) - Resolved mypy type errors in RL module and interface factory
• Routing (ea91e3f) - Fixed mypy type errors and ruff linting issues in routing algorithms
• Sim (3b652dc) - Fixed mypy type errors in test suite and persistence module

Code Quality Improvements:

• Core Module (9141141) - Improved code quality and fixed edge cases discovered during testing

Commands to Reproduce Testing:

# Run all new tests
python -m pytest fusion/ -v

# Run specific module tests
python -m pytest fusion/cli/tests/ -v
python -m pytest fusion/configs/tests/ -v
python -m pytest fusion/core/tests/ -v
python -m pytest fusion/modules/tests/ -v
python -m pytest fusion/interfaces/tests/ -v
python -m pytest fusion/io/tests/ -v
python -m pytest fusion/reporting/tests/ -v
python -m pytest fusion/sim/tests/ -v
python -m pytest fusion/unity/tests/ -v
python -m pytest fusion/utils/tests/ -v
python -m pytest fusion/analysis/tests/ -v

# Type checking
python -m mypy fusion/

# Linting
python -m ruff check fusion/

Test Results:

• Operating System: macOS (Darwin 25.0.0)
• Python Version: 3.11+
• Test Environment: Local development

📊 Impact Analysis

Performance Impact:

• No performance impact
• Performance improved
• Minor performance decrease (acceptable)
• Significant performance impact (needs discussion)

Memory Usage:

• No change in memory usage
• Memory usage optimized
• Minor increase in memory usage
• Significant memory impact

Backward Compatibility:

• Fully backward compatible
• Minor breaking changes with migration path
• Major breaking changes (requires version bump)

Dependencies:

• No new dependencies
• New dependencies added (list in Additional Notes)
• Dependencies removed/updated

✅ Code Quality Checklist

Architecture & Design:

• Follows established architecture patterns
• Code is modular and follows separation of concerns
• Interfaces are well-defined and documented
• Error handling is comprehensive
• Logging is appropriate and informative

Code Standards:

• Code follows project style guidelines
• Variable and function names are descriptive
• Code is properly commented
• Complex logic is documented
• No dead code or unused imports

Security:

• No sensitive information hardcoded
• Input validation performed where needed
• No security vulnerabilities introduced
• Dependencies scanned for vulnerabilities

📚 Documentation

Documentation Updates:

• Code comments added/updated
• API documentation updated (via test coverage)
• Each test module includes comprehensive README
• User guide/tutorial updated
• Configuration reference updated
• CHANGELOG.md updated
• README updated (if needed)

Examples Added:

• Usage examples in test files demonstrate all major functionality
• Configuration examples in test fixtures
• Integration examples showing component interaction

🚀 Deployment

Deployment Considerations:

• Safe to deploy to all environments
• Requires environment-specific configuration
• Needs database migration (if applicable)
• Requires manual steps (document below)

Manual Steps Required:
None - tests are self-contained and run via pytest

🔍 Review Guidelines

For Reviewers:

• PR description is clear and complete
• Code changes align with described functionality
• Tests are comprehensive and pass
• Documentation is adequate
• No obvious security issues
• Performance impact is acceptable

Review Focus Areas:

• Test coverage completeness for critical paths
• Mock/fixture patterns and reusability
• Edge case handling in tests
• Integration between test suites and source code

📝 Additional Notes

Test Organization:

• Old tests in root tests/ directory were removed/consolidated
• New tests are co-located with source code in module-specific tests/ directories
• Each test module includes a comprehensive README documenting test coverage
• Test fixtures and utilities properly organized in conftest.py files

Coverage Summary:

• Total new test code: ~41,305 lines added
• Old test code removed: ~12,594 lines (consolidated/improved)
• Net addition: ~28,711 lines of improved test coverage
• Files changed: 212 files

Key Testing Patterns Used:

• Comprehensive fixture management with pytest
• Mock/patch strategies for external dependencies
• Parameterized tests for edge cases
• Integration tests for component interactions
• Property-based testing where applicable

Module-Specific Test READMEs:
Each test directory includes a README with:

• Overview of what's being tested
• Test coverage breakdown
• Running instructions
• Known limitations
• Future test improvements

Future Work:

• Continue to expand integration tests
• Add performance benchmarking tests
• Expand end-to-end testing scenarios
• Add mutation testing for test quality verification
• Increase test coverage metrics tracking

Related PRs:

• Parent branch: refactor/module-cleanup (coding standards compliance)
• Target release: release/6.0.0

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🏁 Final Checklist

Before submitting this PR, confirm:

• I have followed the contributing guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published