Testing Framework Integration

def fs() -> FakeFilesystem:
    """
    pytest fixture that provides a FakeFilesystem instance.
    
    Automatically patches all filesystem modules (os, os.path, pathlib, shutil, io, open)
    and provides a clean fake filesystem for each test function.
    
    Returns:
        FakeFilesystem instance for creating files and directories
    """

def fs_class() -> FakeFilesystem:
    """
    Class-scoped pytest fixture that provides a FakeFilesystem instance.
    
    Same as fs fixture but shared across all test methods in a test class.
    
    Returns:
        FakeFilesystem instance for creating files and directories
    """

def fs_module() -> FakeFilesystem:
    """
    Module-scoped pytest fixture that provides a FakeFilesystem instance.
    
    Same as fs fixture but shared across all tests in a module.
    
    Returns:
        FakeFilesystem instance for creating files and directories
    """

def fs_session() -> FakeFilesystem:
    """
    Session-scoped pytest fixture that provides a FakeFilesystem instance.
    
    Same as fs fixture but shared across entire test session.
    
    Returns:
        FakeFilesystem instance for creating files and directories
    """

import pytest

def test_file_operations(fs):
    """Test using the fs fixture."""
    # Create test files
    fs.create_file('/test/data.txt', contents='test data')
    fs.create_dir('/test/subdir')
    
    # Test file operations
    import os
    assert os.path.exists('/test/data.txt')
    assert os.path.isfile('/test/data.txt')
    assert os.path.isdir('/test/subdir')
    
    with open('/test/data.txt', 'r') as f:
        content = f.read()
    assert content == 'test data'

def test_pathlib_operations(fs):
    """Test pathlib integration."""
    from pathlib import Path
    
    # Create test file
    fs.create_file('/test/pathlib.txt', contents='pathlib test')
    
    # Use pathlib
    path = Path('/test/pathlib.txt')
    assert path.exists()
    assert path.is_file()
    assert path.read_text() == 'pathlib test'

class TestCase(unittest.TestCase):
    """
    Base test class that provides automatic pyfakefs setup.
    
    Inherits from unittest.TestCase and automatically patches filesystem modules.
    Provides access to the fake filesystem via the 'fs' attribute.
    """
    fs: FakeFilesystem
    
    def setUpPyfakefs(
        self,
        modules_to_reload: List[str] = None,
        modules_to_patch: Dict[str, str] = None,
        additional_skip_names: List[str] = None,
        use_known_patches: bool = True,
        use_cache: bool = True,
        **kwargs
    ) -> None:
        """
        Set up pyfakefs for this test case.
        
        Args:
            modules_to_reload: List of modules to reload after patching
            modules_to_patch: Dict of module names to patch  
            additional_skip_names: Additional modules to skip patching
            use_known_patches: Whether to use known patches for common modules
            use_cache: Whether to use filesystem caching
        """
    
    def tearDownPyfakefs(self) -> None:
        """Tear down pyfakefs and restore real filesystem modules."""
    
    @classmethod
    def setUpClassPyfakefs(
        cls,
        modules_to_reload: List[str] = None,
        modules_to_patch: Dict[str, str] = None,
        additional_skip_names: List[str] = None,
        use_known_patches: bool = True,
        use_cache: bool = True,
        **kwargs
    ) -> None:
        """
        Set up pyfakefs for the entire test class (Python 3.8+).
        
        Args:
            modules_to_reload: List of modules to reload after patching
            modules_to_patch: Dict of module names to patch  
            additional_skip_names: Additional modules to skip patching
            use_known_patches: Whether to use known patches for common modules
            use_cache: Whether to use filesystem caching
        """

import unittest
import os
from pyfakefs.fake_filesystem_unittest import TestCase

class MyTest(TestCase):
    def setUp(self):
        self.setUpPyfakefs()
    
    def test_file_creation(self):
        # Create a test file
        self.fs.create_file('/test/example.txt', contents='Hello World')
        
        # Test standard file operations
        self.assertTrue(os.path.exists('/test/example.txt'))
        
        with open('/test/example.txt', 'r') as f:
            content = f.read()
        self.assertEqual(content, 'Hello World')
    
    def test_directory_operations(self):
        # Create directory structure
        self.fs.create_dir('/test/subdir')
        self.fs.create_file('/test/subdir/file.txt', contents='test')
        
        # Test directory operations
        self.assertTrue(os.path.isdir('/test/subdir'))
        files = os.listdir('/test/subdir')
        self.assertEqual(files, ['file.txt'])

class TestCaseMixin:
    """
    Mixin for adding pyfakefs to existing test classes.
    
    Use this when you can't inherit from pyfakefs.TestCase but want
    to add fake filesystem functionality to your tests.
    """
    fs: FakeFilesystem
    
    def setUpPyfakefs(self, **kwargs) -> None:
        """Set up pyfakefs for this test."""
    
    def tearDownPyfakefs(self) -> None:
        """Tear down pyfakefs and restore real filesystem."""

import unittest
from pyfakefs.fake_filesystem_unittest import TestCaseMixin

class MyExistingTest(unittest.TestCase, TestCaseMixin):
    def setUp(self):
        # Existing setup code
        super().setUp()
        self.setUpPyfakefs()
        
        # Additional setup with fake filesystem
        self.fs.create_file('/config.ini', contents='[section]\nkey=value')
    
    def tearDown(self):
        self.tearDownPyfakefs()
        super().tearDown()
    
    def test_config_reading(self):
        # Test code that reads /config.ini
        import configparser
        config = configparser.ConfigParser()
        config.read('/config.ini')
        self.assertEqual(config['section']['key'], 'value')

def patchfs(
    additional_skip_names: List[str] = None,
    modules_to_reload: List[str] = None,
    modules_to_patch: Dict[str, str] = None,
    use_known_patches: bool = True,
    use_cache: bool = True
) -> Callable:
    """
    Decorator to patch filesystem modules for a single test function.
    
    The decorated function receives a 'fs' parameter with the FakeFilesystem instance.
    
    Args:
        additional_skip_names: Additional modules to skip patching
        modules_to_reload: List of modules to reload after patching
        modules_to_patch: Dict of module names to patch
        use_known_patches: Whether to use known patches for common modules
        use_cache: Whether to use filesystem caching
        
    Returns:
        Decorated function with filesystem patching
    """

import unittest
import os
from pyfakefs.fake_filesystem_unittest import patchfs

class MyTest(unittest.TestCase):
    @patchfs
    def test_with_fake_fs(self, fs):
        # Create test files
        fs.create_file('/test.txt', contents='test content')
        
        # Test file operations
        self.assertTrue(os.path.exists('/test.txt'))
        with open('/test.txt', 'r') as f:
            content = f.read()
        self.assertEqual(content, 'test content')
    
    def test_without_fake_fs(self):
        # This test uses the real filesystem
        pass

class Patcher:
    """
    Context manager for temporarily patching filesystem modules.
    
    Provides manual control over when filesystem patching is active.
    """
    fs: FakeFilesystem
    
    def __init__(
        self,
        additional_skip_names: List[str] = None,
        modules_to_reload: List[str] = None,
        modules_to_patch: Dict[str, str] = None,
        use_known_patches: bool = True,
        use_cache: bool = True
    ) -> None:
        """
        Initialize the patcher.
        
        Args:
            additional_skip_names: Additional modules to skip patching
            modules_to_reload: List of modules to reload after patching
            modules_to_patch: Dict of module names to patch
            use_known_patches: Whether to use known patches for common modules
            use_cache: Whether to use filesystem caching
        """
    
    def __enter__(self) -> 'Patcher':
        """Enter the context and start filesystem patching."""
    
    def __exit__(self, exc_type, exc_val, exc_tb) -> None:
        """Exit the context and stop filesystem patching."""

class Pause:
    """
    Context manager for temporarily pausing filesystem patching.
    
    Allows temporary access to the real filesystem during test execution.
    """
    
    def __init__(self, patcher: Union[Patcher, TestCase, FakeFilesystem]) -> None:
        """
        Initialize the pause context manager.
        
        Args:
            patcher: Patcher instance, TestCase, or FakeFilesystem to pause
        """
    
    def __enter__(self) -> 'Pause':
        """Enter the context and pause filesystem patching."""
    
    def __exit__(self, exc_type, exc_val, exc_tb) -> None:
        """Exit the context and resume filesystem patching."""

import os
from pyfakefs.fake_filesystem_unittest import Patcher

def test_with_context_manager():
    # Code here uses real filesystem
    
    with Patcher() as patcher:
        # Create fake files
        patcher.fs.create_file('/fake.txt', contents='fake content')
        
        # Test with fake filesystem
        assert os.path.exists('/fake.txt')
        with open('/fake.txt', 'r') as f:
            content = f.read()
        assert content == 'fake content'
    
    # Code here uses real filesystem again

def pytest_addoption(parser) -> None:
    """Add pyfakefs-specific command line options to pytest."""

def pytest_configure(config) -> None:
    """Configure pyfakefs for the pytest session."""

# Skip patching specific modules
pytest --fs-skip-modules=module1,module2

# Use dynamic patching (slower but more compatible)
pytest --fs-no-cache

# Debug filesystem patching
pytest --fs-debug

from typing import List, Dict, Callable, Any, Optional, Union

# Configuration types
ModulesToPatch = Dict[str, str]
ModulesToReload = List[str] 
SkipNames = List[str]

# Decorator type
PatchfsDecorator = Callable[[Callable], Callable]

def set_uid(uid: int) -> None:
    """
    Set the current user ID for filesystem operations.
    
    Args:
        uid: User ID to emulate
    """

def set_gid(gid: int) -> None:
    """
    Set the current group ID for filesystem operations.
    
    Args:
        gid: Group ID to emulate
    """

def get_uid() -> int:
    """
    Get the current user ID being emulated.
    
    Returns:
        Current user ID
    """

def get_gid() -> int:
    """
    Get the current group ID being emulated.
    
    Returns:
        Current group ID  
    """

def reset_ids() -> None:
    """Reset user and group IDs to defaults."""

def is_root() -> bool:
    """
    Check if currently emulating root user.
    
    Returns:
        True if uid == 0, False otherwise
    """

def reload_cleanup_handler(name: str) -> None:
    """
    Cleanup handler for module reloading.
    
    Args:
        name: Module name to clean up
    """

from pyfakefs.helpers import set_uid, set_gid, reset_ids, is_root

def test_permission_checks(fs):
    # Test as non-root user
    set_uid(1000)
    set_gid(1000)
    
    # Create file with restricted permissions
    fs.create_file('/secret.txt', contents='confidential', st_mode=0o600)
    
    # Test access as different user
    set_uid(1001)
    try:
        with open('/secret.txt', 'r') as f:
            content = f.read()  # Should raise PermissionError
    except PermissionError:
        print("Access denied as expected")
    
    # Reset to defaults
    reset_ids()

def load_doctests(
    loader: unittest.TestLoader,
    tests: unittest.TestSuite,
    ignore: Any,
    module: Any,
    additional_skip_names: List[str] = None,
    **kwargs
) -> unittest.TestSuite:
    """
    Load doctests with pyfakefs support.
    
    Use this function in your test module's load_tests function to automatically
    patch filesystem modules when running doctests.
    
    Args:
        loader: Test loader instance
        tests: Existing test suite
        ignore: Ignored parameter (for compatibility)
        module: Module containing doctests
        additional_skip_names: Additional modules to skip patching
        **kwargs: Additional pyfakefs configuration options
        
    Returns:
        Updated test suite with doctests
    """

import doctest
import unittest
from pyfakefs import fake_filesystem_unittest

def load_tests(loader, tests, ignore):
    """Load doctests with pyfakefs support."""
    return fake_filesystem_unittest.load_doctests(
        loader, tests, ignore, __name__
    )

# Example doctest in your module:
def create_config_file():
    """
    Create a configuration file.
    
    >>> create_config_file()
    >>> import os
    >>> os.path.exists('/config/settings.ini')
    True
    >>> with open('/config/settings.ini', 'r') as f:
    ...     content = f.read()
    >>> 'debug=true' in content
    True
    """
    import os
    os.makedirs('/config', exist_ok=True)
    with open('/config/settings.ini', 'w') as f:
        f.write('[DEFAULT]\ndebug=true\n')