Add Comprehensive Test Suite

[RISHABH4SAHNI]

Overview
The project needs a comprehensive test suite to ensure code reliability and maintainability. Currently, we have minimal testing coverage.

Goals
[ ] Achieve >85% code coverage
[ ] Add unit tests for all modules
[ ] Set up CI/CD testing pipeline
[ ] Add integration tests

Tests Needed
Unit Tests (tests/unit/)
[ ] test_preprocessing.py - Data processing functions
[ ] test_gcn_model.py - GCN model components
[ ] test_baseline_models.py - Traditional ML models
[ ] test_evaluation.py - Metrics and evaluation
[ ] test_graph_construction.py - Graph building

Integration Tests (tests/integration/)
[ ] test_training_pipeline.py - End-to-end training
[ ] test_data_flow.py - Component integration

🔧 Requirements
pytest>=7.0.0
pytest-cov>=4.0.0
pytest-mock>=3.10.0

Acceptance Criteria
[ ] 85%+ code coverage
[ ] All core functions tested
[ ] Tests run in CI/CD
[ ] Clear test documentation

Implementation
Set up pytest configuration
Write unit tests for each module
Add integration tests
Configure GitHub Actions
Priority: High | Effort: 1-2 weeks | Difficulty: Beginner-Intermediate