Exception Handling

class MoleculeError(Exception):
    """
    Generic Molecule error.
    
    Custom exception to handle scenario run failures with support
    for exit codes, detailed messages, and warning aggregation.
    
    Args:
        message (str): The message to display about the problem
        code (int): Exit code to use when exiting (default: 1)
        warns (Sequence[WarningMessage]): Warnings about the problem to issue
        
    Attributes:
        code (int): Exit code for process termination
    """
    
    def __init__(self, message="", code=1, warns=()):
        """Initialize MoleculeError with message, code, and warnings."""

class ScenarioFailureError(MoleculeError):
    """
    Details about a scenario that failed.
    
    Specialized exception for scenario execution failures,
    inheriting all capabilities from MoleculeError.
    """

class MoleculeRuntimeWarning(RuntimeWarning):
    """
    A runtime warning used by Molecule and its plugins.
    
    Base warning class for Molecule-specific runtime issues
    that don't prevent execution but should be reported.
    """

class IncompatibleMoleculeRuntimeWarning(MoleculeRuntimeWarning):
    """
    A warning noting an unsupported runtime environment.
    
    Issued when Molecule detects compatibility issues with
    the current runtime environment or dependencies.
    """

from molecule.exceptions import MoleculeError, ScenarioFailureError

try:
    # Molecule operation that might fail
    config = Config()
    result = config.driver.status()
except MoleculeError as e:
    print(f"Molecule error occurred: {e}")
    print(f"Exit code: {e.code}")
    # Handle the error appropriately
    exit(e.code)
except ScenarioFailureError as e:
    print(f"Scenario failed: {e}")
    # Specific handling for scenario failures
    exit(e.code)

from molecule.exceptions import MoleculeError
import warnings

def validate_configuration():
    """Validate Molecule configuration and raise errors if invalid."""
    
    # Check for missing required files
    if not os.path.exists("molecule.yml"):
        raise MoleculeError(
            message="molecule.yml configuration file not found",
            code=4  # RC_SETUP_ERROR
        )
    
    # Check for compatibility issues
    warning_msgs = []
    if incompatible_version_detected():
        warning = warnings.WarningMessage(
            message="Incompatible version detected",
            category=UserWarning,
            filename=__file__,
            lineno=0
        )
        warning_msgs.append(warning)
    
    if warning_msgs:
        raise MoleculeError(
            message="Configuration validation failed",
            code=1,
            warns=warning_msgs
        )

from molecule.driver.base import Driver
from molecule.exceptions import MoleculeError

class CustomDriver(Driver):
    def sanity_checks(self):
        """Validate driver prerequisites."""
        
        # Check for required external tools
        if not self._tool_available("custom-tool"):
            raise MoleculeError(
                message="custom-tool is required but not found in PATH",
                code=4  # RC_SETUP_ERROR
            )
        
        # Check for valid configuration
        if not self.options.get("api_key"):
            raise MoleculeError(
                message="API key is required for custom driver",
                code=4
            )
    
    def _tool_available(self, tool_name):
        """Check if external tool is available."""
        import subprocess
        try:
            subprocess.run([tool_name, "--version"], 
                         capture_output=True, check=True)
            return True
        except (subprocess.CalledProcessError, FileNotFoundError):
            return False

from molecule.verifier.base import Verifier
from molecule.exceptions import MoleculeError

class CustomVerifier(Verifier):
    def execute(self, action_args):
        """Execute verification tests with error handling."""
        
        try:
            result = self._run_tests(action_args)
            
            if result.returncode != 0:
                raise ScenarioFailureError(
                    message=f"Verification tests failed: {result.stderr}",
                    code=result.returncode
                )
                
            return result
            
        except FileNotFoundError as e:
            raise MoleculeError(
                message=f"Test runner not found: {e}",
                code=4  # RC_SETUP_ERROR
            )
        except TimeoutError:
            raise MoleculeError(
                message="Verification tests timed out",
                code=3  # RC_TIMEOUT
            )

import warnings
from molecule.api import MoleculeRuntimeWarning, IncompatibleMoleculeRuntimeWarning

def check_runtime_compatibility():
    """Check runtime environment and issue warnings."""
    
    # Check Python version compatibility
    import sys
    if sys.version_info < (3, 10):
        warnings.warn(
            "Python version < 3.10 is not officially supported",
            IncompatibleMoleculeRuntimeWarning,
            stacklevel=2
        )
    
    # Check for deprecated features
    if using_deprecated_feature():
        warnings.warn(
            "This feature is deprecated and will be removed in a future version",
            MoleculeRuntimeWarning,
            stacklevel=2
        )

# Configure warning filters
warnings.filterwarnings("always", category=MoleculeRuntimeWarning)
warnings.filterwarnings("error", category=IncompatibleMoleculeRuntimeWarning)

from molecule.constants import (
    RC_SUCCESS,        # 0
    RC_TIMEOUT,        # 3
    RC_SETUP_ERROR,    # 4
    RC_UNKNOWN_ERROR   # 5
)

def handle_molecule_operation():
    """Handle Molecule operation with proper exit codes."""
    
    try:
        # Perform Molecule operation
        result = run_molecule_test()
        return RC_SUCCESS
        
    except TimeoutError:
        return RC_TIMEOUT
        
    except MoleculeError as e:
        if "setup" in str(e).lower():
            return RC_SETUP_ERROR
        return e.code
        
    except Exception:
        return RC_UNKNOWN_ERROR