Add comprehensive test suites for backend and frontend

[marota]

Summary

This PR adds extensive test coverage for both the backend FastAPI application and frontend React components, along with necessary test infrastructure and configuration.

Key Changes

Backend Testing

• API Endpoint Tests (test_api_endpoints.py): Comprehensive test suite for all FastAPI endpoints using TestClient with mocked services, covering:

  • Branch and voltage level retrieval
  • Network and N-1 diagrams
  • Analysis execution with streaming NDJSON responses
  • Action variant diagrams and focused diagrams
  • Manual action simulation
  • Error handling and edge cases

• Network Service Tests (test_network_service.py): Tests for network loading and querying:

  • File and directory loading with .xiidm and .xml support
  • Disconnectable elements retrieval
  • Voltage level and nominal voltage queries
  • Error handling for missing networks

• Recommender Service Tests (test_compute_deltas.py): Tests for flow delta computation:

  • Delta calculation between network states
  • Categorization of deltas (positive, negative, grey)
  • Threshold-based filtering logic

• Utility Tests (test_sanitize.py): Tests for JSON sanitization utility:

  • NumPy type conversion (int32, int64, float32, float64)
  • Array and nested structure handling
  • Dictionary key conversion and deep recursion

• Test Infrastructure (conftest.py): Shared pytest fixtures and mocking:

  • Mock modules for unavailable domain packages (pypowsybl, expert_op4grid_recommender)
  • Mock network fixture with realistic test data
  • Mock network service fixture

Frontend Testing

• API Client Tests (api.test.ts): Tests for axios-based API client:

  • Configuration updates
  • Data retrieval endpoints
  • Streaming response parsing (NDJSON)
  • Error handling

• SVG Utilities Tests (svgUtils.test.ts): Tests for SVG processing:

  • ViewBox extraction and parsing
  • SVG optimization for large grids
  • Metadata indexing and querying
  • Action target line identification

• Component Tests:

  • VisualizationPanel.test.tsx: Tab switching, diagram loading, zoom controls
  • OverloadPanel.test.tsx: Overload display and asset click handling

Configuration

• pytest.ini: Pytest configuration for backend test discovery
• vite.config.ts: Updated with Vitest configuration for frontend testing
• frontend/package.json: Added test and test:watch scripts
• frontend/src/test/setup.ts: Test environment setup for React Testing Library

Notable Implementation Details

• Backend tests use unittest.mock to patch singleton services before app import, ensuring clean test isolation
• Streaming response tests verify NDJSON format parsing with proper event type handling
• Frontend tests use Vitest with React Testing Library for component testing
• Mock modules are installed into sys.modules before production imports to handle unavailable domain packages in CI environments
• Tests cover both happy paths and error scenarios with appropriate assertions

https://claude.ai/code/session_011cg6PjoX5hfQ1yNWRfmpv7