test_error_handling.py

#!/usr/bin/env python3
"""
Test script for SMILES error handling and validation.
"""

from rdkit import Chem
from rdkit.Chem import Draw

def validate_smiles(smiles):
    """Validate SMILES string and return error message if invalid."""
    if not smiles or not smiles.strip():
        return "Please enter a SMILES string"
    
    mol = Chem.MolFromSmiles(smiles.strip())
    if not mol:
        return f"Invalid SMILES string: '{smiles}'\n\n**Common issues:**\n- Unclosed parentheses or brackets\n- Invalid characters\n- Malformed ring notation\n- Incorrect stereochemistry notation\n\n**Try:**\n- Simple molecules first (e.g., 'CO' for methanol)\n- Check parentheses balance\n- Use standard SMILES notation"
    
    return None

def test_smiles_validation():
    """Test various SMILES strings for validation."""
    
    test_cases = [
        # Valid SMILES
        ("CO", "Methanol - should work"),
        ("CCO", "Ethanol - should work"),
        ("c1ccccc1", "Benzene - should work"),
        ("C[C@H](N)C(=O)O", "Alanine - should work"),
        
        # Invalid SMILES
        ("", "Empty string - should fail"),
        ("invalid", "Invalid text - should fail"),
        ("C([C@@H]1[C@H]([C@@H]([C@H]([C@H](O1)O)O)O)O", "Complex glucose - should fail"),
        ("C(C", "Unclosed parentheses - should fail"),
        ("C1C1", "Invalid ring - should fail"),
        ("C[invalid]", "Invalid bracket - should fail"),
    ]
    
    print("🧪 Testing SMILES Validation")
    print("=" * 50)
    
    for smiles, description in test_cases:
        print(f"\n📊 Testing: {description}")
        print(f"SMILES: '{smiles}'")
        
        error = validate_smiles(smiles)
        if error:
            print(f"❌ Validation failed: {error[:100]}...")
        else:
            print("✅ Validation passed")
        
        print("-" * 30)

if __name__ == "__main__":
    test_smiles_validation()