feat: add unit tests and integration tests

Context

This MR implements comprehensive unit and integration testing for the aidge_export_tensorrt module. The test suite provides complete coverage of export functionality, file generation, and plugin registry operations to ensure code reliability and maintainability.

Modified files

• test_export.py (18 tests) - Unit tests for main export functionality
• test_file_generation.py (9 tests) - Unit tests for file and plugin generation
• test_plugin_registry.py (6 tests) - Unit tests for plugin registry operations
• test_integration.py (8 tests) - Integration tests for end-to-end functionality

Total: 41 tests covering all module functionality

Detailed major modifications

Test Architecture & Coverage

Export Functionality (18 tests)

• Input Validation: GraphView/string type detection, ONNX extension validation with endswith checks
• File Operations: Directory creation with os.makedirs, file copying via shutil.copy, renaming to model.onnx
• TensorRT Integration: Version-specific static file copying (default: 10.10) with shutil.copytree
• PyBind11 Integration: Git cloning with subprocess.run management and error handling
• Error Handling: Invalid inputs, missing files, CalledProcessError and FileNotFoundError scenarios

File Generation (9 tests)

• Template Rendering: Jinja2 template processing with variable substitution and nested directory support
• Directory Structure: Multi-level directory creation for plugins using os.makedirs
• Plugin Generation: .hpp and .cu file creation in plugins/pluginname/ structure
• Error Handling: Template validation and file system error simulation

Plugin Registry (6 tests)

• Registration System: Single/multiple plugin decorators with @plugin_registry.register
• Key Management: Multiple aliases for same plugin using list-based key registration
• Functionality Preservation: Decorated function callability maintained after registration

Integration Tests (8 tests)

• End-to-End Workflow: Complete export with ONNX files and GraphView objects
• Real-World Scenarios: Concurrent operations with thread safety, large file handling (1MB+)
• Error Integration: File not found, invalid inputs in full context with proper cleanup
• Version Handling: Different TensorRT version support (8.6, 10.10) with static file management

Test Environment & Mocking Strategy

Isolation & Cleanup

• Temporary Directories: tempfile.mkdtemp() for isolated testing environment
• Automatic Cleanup: shutil.rmtree() in tearDown() methods
• State Restoration: Original module state restored after each test

Mocking Architecture

Component	Mock Target	Purpose
External Dependencies	aidge_core, aidge_onnx	Isolate unit under test from external modules
File Operations	shutil.copy, shutil.copytree, os.rename	Control file system behavior without actual I/O
System Calls	subprocess.run	Avoid actual git operations during testing
Error Conditions	File not found scenarios	Test error handling paths and edge cases