Helper Utilities

def try_import(name, alternative=None, error_callback=None):
    """
    Attempt to import a module, with a fallback.
    
    Safely attempts to import a module or attribute, returning
    an alternative value if the import fails. Useful for optional
    dependencies and cross-version compatibility.
    
    Args:
        name (str): The name of the object to import (e.g., 'os.path.join')
        alternative: The value to return if import fails (default: None)
        error_callback (callable): Function called with ImportError if import fails
        
    Returns:
        The imported object or the alternative value
        
    Example:
        # Try to import optional dependency
        numpy = try_import('numpy', alternative=None)
        if numpy is not None:
            # Use numpy functionality
            pass
            
        # Import specific function with fallback
        json_loads = try_import('orjson.loads', json.loads)
    """

def map_values(function, dictionary):
    """
    Map function across the values of a dictionary.
    
    Applies a function to each value in a dictionary,
    preserving the key-value structure.
    
    Args:
        function (callable): Function to apply to each value
        dictionary (dict): Dictionary to transform
        
    Returns:
        dict: New dictionary with transformed values
        
    Example:
        data = {'a': 1, 'b': 2, 'c': 3}
        doubled = map_values(lambda x: x * 2, data)
        # {'a': 2, 'b': 4, 'c': 6}
    """

def filter_values(function, dictionary):
    """
    Filter dictionary by its values using a predicate function.
    
    Returns a new dictionary containing only the key-value pairs
    where the value satisfies the predicate function.
    
    Args:
        function (callable): Predicate function returning bool
        dictionary (dict): Dictionary to filter
        
    Returns:
        dict: Filtered dictionary
        
    Example:
        data = {'a': 1, 'b': 2, 'c': 3, 'd': 4}
        evens = filter_values(lambda x: x % 2 == 0, data)
        # {'b': 2, 'd': 4}
    """

def dict_subtract(a, b):
    """
    Return the part of dictionary a that's not in dictionary b.
    
    Creates a new dictionary containing key-value pairs from 'a'
    whose keys are not present in 'b'.
    
    Args:
        a (dict): Source dictionary
        b (dict): Dictionary whose keys to exclude
        
    Returns:
        dict: Dictionary with keys from a not in b
        
    Example:
        a = {'x': 1, 'y': 2, 'z': 3}
        b = {'y': 5, 'w': 6}
        result = dict_subtract(a, b)
        # {'x': 1, 'z': 3}
    """

def list_subtract(a, b):
    """
    Return a list with elements of a not in b.
    
    Creates a new list containing elements from 'a' that are
    not present in 'b'. If an element appears multiple times
    in 'a' and once in 'b', it will appear n-1 times in result.
    
    Args:
        a (list): Source list
        b (list): List of elements to remove
        
    Returns:
        list: List with elements from a not in b
        
    Example:
        a = [1, 2, 3, 2, 4]
        b = [2, 5]
        result = list_subtract(a, b)
        # [1, 3, 2, 4]  (one instance of 2 removed)
    """

def clone_test_with_new_id(test, new_id):
    """
    Clone a test with a new test ID.
    
    Creates a copy of a test case with a different identifier,
    useful for parameterized testing or test case variations.
    
    Args:
        test: Original TestCase instance
        new_id (str): New test identifier
        
    Returns:
        TestCase: Cloned test with new ID
        
    Example:
        original_test = MyTest('test_function')
        variant_test = clone_test_with_new_id(original_test, 'test_function_variant')
    """

def iterate_tests(test_suite_or_case):
    """
    Iterate through all individual tests in a test suite.
    
    Recursively flattens test suites to yield individual
    test cases, useful for test discovery and analysis.
    
    Args:
        test_suite_or_case: TestSuite or TestCase to iterate
        
    Yields:
        TestCase: Individual test cases
        
    Example:
        suite = TestSuite()
        # ... add tests to suite ...
        for test in iterate_tests(suite):
            print(f"Found test: {test.id()}")
    """

def unique_text_generator():
    """
    Generate unique text strings for test isolation.
    
    Creates a generator that yields unique text strings,
    useful for generating unique identifiers in tests.
    
    Yields:
        str: Unique text strings
        
    Example:
        generator = unique_text_generator()
        unique1 = next(generator)  # "0"
        unique2 = next(generator)  # "1"
        unique3 = next(generator)  # "2"
    """

class MonkeyPatcher:
    """
    Apply and remove multiple patches as a coordinated group.
    
    Manages multiple monkey patches with automatic cleanup,
    ensuring all patches are properly restored after use.
    """
    
    def __init__(self):
        """Create a new MonkeyPatcher instance."""
    
    def add_patch(self, obj, attribute, new_value):
        """
        Add a patch to be applied.
        
        Args:
            obj: Object to patch
            attribute (str): Attribute name to patch
            new_value: New value for the attribute
        """
    
    def patch(self):
        """
        Apply all registered patches.
        
        Applies all patches that have been registered with add_patch().
        Should be called before the code that needs the patches.
        """
    
    def restore(self):
        """
        Restore all patched attributes to their original values.
        
        Undoes all patches applied by patch(), restoring the
        original attribute values.
        """
    
    def __enter__(self):
        """
        Context manager entry - applies patches.
        
        Returns:
            MonkeyPatcher: Self for context manager protocol
        """
        self.patch()
        return self
    
    def __exit__(self, exc_type, exc_val, exc_tb):
        """
        Context manager exit - restores patches.
        
        Args:
            exc_type: Exception type (if any)
            exc_val: Exception value (if any) 
            exc_tb: Exception traceback (if any)
        """
        self.restore()

def patch(obj, attribute, new_value):
    """
    Apply a simple monkey patch.
    
    Convenience function for applying a single patch.
    For multiple patches, use MonkeyPatcher class.
    
    Args:
        obj: Object to patch
        attribute (str): Attribute name to patch  
        new_value: New value for the attribute
        
    Returns:
        The original value that was replaced
        
    Example:
        # Patch a function temporarily
        original = patch(os, 'getcwd', lambda: '/fake/path')
        try:
            # Code that uses os.getcwd()
            pass
        finally:
            # Restore original
            setattr(os, 'getcwd', original)
    """

def assert_that(matchee, matcher, message='', verbose=False):
    """
    Assert that matchee matches the given matcher.
    
    Standalone assertion function using testtools matchers,
    can be used outside of TestCase instances for utility
    functions and general-purpose assertions.
    
    Args:
        matchee: Object to be matched
        matcher: Matcher instance to apply
        message (str): Optional failure message
        verbose (bool): Include detailed mismatch information
        
    Raises:
        MismatchError: If matcher does not match matchee
        
    Example:
        from testtools.assertions import assert_that
        from testtools.matchers import Equals, GreaterThan
        
        # Use in utility functions
        def validate_config(config):
            assert_that(config['timeout'], GreaterThan(0))
            assert_that(config['host'], Contains('.'))
    """

def reraise(exc_type, exc_value, traceback):
    """
    Re-raise an exception with its original traceback.
    
    Properly re-raises exceptions preserving the original
    traceback information across Python versions.
    
    Args:
        exc_type: Exception type
        exc_value: Exception instance
        traceback: Exception traceback
    """

def text_repr(obj):
    """
    Get text representation with proper escaping.
    
    Returns a properly escaped text representation of an object,
    handling unicode and special characters correctly.
    
    Args:
        obj: Object to represent
        
    Returns:
        str: Escaped text representation
    """

def unicode_output_stream(stream):
    """
    Get unicode-capable output stream.
    
    Wraps a stream to ensure it can handle unicode output
    properly across different Python versions and platforms.
    
    Args:
        stream: Original output stream
        
    Returns:
        Stream: Unicode-capable stream wrapper
    """

import testtools
from testtools.helpers import try_import

class MyTest(testtools.TestCase):
    
    def setUp(self):
        super().setUp()
        
        # Try to import optional dependencies
        self.numpy = try_import('numpy')
        self.pandas = try_import('pandas')
        self.requests = try_import('requests', error_callback=self._log_import_error)
    
    def _log_import_error(self, error):
        """Log import errors for debugging."""
        self.addDetail('import_error', 
                      testtools.content.text_content(str(error)))
    
    def test_with_optional_numpy(self):
        if self.numpy is None:
            self.skip("NumPy not available")
        
        # Use numpy functionality
        arr = self.numpy.array([1, 2, 3])
        self.assertEqual(len(arr), 3)
    
    def test_with_fallback_json(self):
        # Use fast JSON library if available, fall back to standard
        json_loads = try_import('orjson.loads', alternative=json.loads)
        json_dumps = try_import('orjson.dumps', alternative=json.dumps)
        
        data = {'test': True, 'value': 42}
        serialized = json_dumps(data)
        deserialized = json_loads(serialized)
        
        self.assertEqual(deserialized, data)

import testtools
from testtools.helpers import map_values, filter_values, dict_subtract

class DataProcessingTest(testtools.TestCase):
    
    def test_data_transformation(self):
        # Original data
        raw_data = {
            'temperature': 20,
            'humidity': 65,
            'pressure': 1013,
            'wind_speed': 15
        }
        
        # Transform all values (Celsius to Fahrenheit)
        fahrenheit_data = map_values(lambda c: c * 9/5 + 32, 
                                   {'temperature': raw_data['temperature']})
        self.assertEqual(fahrenheit_data['temperature'], 68.0)
        
        # Filter for specific conditions
        high_values = filter_values(lambda x: x > 50, raw_data)
        self.assertIn('humidity', high_values)
        self.assertIn('pressure', high_values)
        self.assertNotIn('temperature', high_values)
    
    def test_configuration_merge(self):
        # Base configuration
        base_config = {
            'host': 'localhost',
            'port': 8080,
            'debug': False,
            'timeout': 30
        }
        
        # Environment-specific overrides
        production_overrides = {
            'host': 'prod.example.com',
            'debug': False,
            'ssl': True
        }
        
        # Get settings that are only in base config
        base_only = dict_subtract(base_config, production_overrides)
        self.assertEqual(base_only, {'port': 8080, 'timeout': 30})
        
        # Merge configurations
        final_config = {**base_config, **production_overrides}
        self.assertEqual(final_config['host'], 'prod.example.com')
        self.assertTrue(final_config['ssl'])

import testtools
from testtools.helpers import MonkeyPatcher
import os
import time

class MonkeyPatchTest(testtools.TestCase):
    
    def test_with_context_manager(self):
        # Use MonkeyPatcher as context manager
        with MonkeyPatcher() as patcher:
            patcher.add_patch(os, 'getcwd', lambda: '/fake/working/dir')
            patcher.add_patch(time, 'time', lambda: 1234567890.0)
            
            # Test code that uses patched functions
            current_dir = os.getcwd()
            current_time = time.time()
            
            self.assertEqual(current_dir, '/fake/working/dir')
            self.assertEqual(current_time, 1234567890.0)
        
        # Outside context, original functions are restored
        self.assertNotEqual(os.getcwd(), '/fake/working/dir')
    
    def test_manual_patching(self):
        patcher = MonkeyPatcher()
        
        # Mock file system operations
        patcher.add_patch(os.path, 'exists', lambda path: path == '/fake/file')
        patcher.add_patch(os.path, 'isfile', lambda path: path.endswith('.txt'))
        
        try:
            patcher.patch()
            
            # Test with mocked file system
            self.assertTrue(os.path.exists('/fake/file'))
            self.assertFalse(os.path.exists('/other/file'))
            self.assertTrue(os.path.isfile('document.txt'))
            self.assertFalse(os.path.isfile('directory'))
            
        finally:
            patcher.restore()
    
    def test_method_patching(self):
        # Patch methods on test objects
        class MockService:
            def get_data(self):
                return "original data"
        
        service = MockService()
        patcher = MonkeyPatcher()
        patcher.add_patch(service, 'get_data', lambda: "mocked data")
        
        with patcher:
            result = service.get_data()
            self.assertEqual(result, "mocked data")
        
        # Method restored after context
        result = service.get_data()
        self.assertEqual(result, "original data")

import testtools
from testtools.helpers import iterate_tests, clone_test_with_new_id

class TestOrganizationExample(testtools.TestCase):
    
    def test_suite_analysis(self):
        # Create a test suite
        suite = testtools.TestSuite()
        suite.addTest(TestOrganizationExample('test_method_1'))
        suite.addTest(TestOrganizationExample('test_method_2'))
        
        # Analyze all tests in suite
        test_count = 0
        test_names = []
        
        for test in iterate_tests(suite):
            test_count += 1
            test_names.append(test.id())
        
        self.assertEqual(test_count, 2)
        self.assertIn('TestOrganizationExample.test_method_1', test_names)
    
    def test_method_1(self):
        self.assertTrue(True)
    
    def test_method_2(self):
        self.assertTrue(True)

def create_parameterized_tests():
    """Create multiple test variants from a base test."""
    base_test = TestOrganizationExample('test_method_1')
    
    # Create variants with different parameters
    variants = []
    for i, param in enumerate(['param1', 'param2', 'param3']):
        variant = clone_test_with_new_id(base_test, f'test_method_1_variant_{i}')
        variant.test_param = param  # Add parameter to test
        variants.append(variant)
    
    return variants

class TestWithParameters(testtools.TestCase):
    
    def test_parameter_injection(self):
        # Use parameter if available
        param = getattr(self, 'test_param', 'default')
        self.assertIsNotNone(param)
        
        # Test behavior varies by parameter
        if param == 'param1':
            self.assertEqual(param, 'param1')
        else:
            self.assertNotEqual(param, 'param1')

from testtools.assertions import assert_that
from testtools.matchers import Equals, GreaterThan, Contains, MatchesDict

def validate_user_data(user_data):
    """Validate user data using testtools assertions."""
    # Use standalone assertions for validation
    assert_that(user_data, MatchesDict({
        'id': GreaterThan(0),
        'name': Contains('@'),  # Assuming email format
        'age': GreaterThan(0)
    }))

def process_configuration(config_file):
    """Process configuration with validation."""
    config = load_config(config_file)
    
    # Validate required fields
    assert_that(config.get('database_url'), Contains('://'))
    assert_that(config.get('port'), GreaterThan(1000))
    assert_that(config.get('debug'), Equals(False))
    
    return config

# Usage in non-test code
try:
    user = {'id': 123, 'name': 'user@example.com', 'age': 25}
    validate_user_data(user)
    print("User data is valid")
except MismatchError as e:
    print(f"Validation failed: {e}")

import testtools
from testtools.helpers import *
from testtools.matchers import *

class IntegratedUtilityTest(testtools.TestCase):
    
    def setUp(self):
        super().setUp()
        
        # Set up test environment with utilities
        self.patcher = MonkeyPatcher()
        self.unique_id_gen = unique_text_generator()
        
        # Mock external dependencies
        self.requests = try_import('requests')
        if self.requests:
            self.patcher.add_patch(self.requests, 'get', self._mock_http_get)
            self.patcher.patch()
    
    def tearDown(self):
        if hasattr(self, 'patcher'):
            self.patcher.restore()
        super().tearDown()
    
    def _mock_http_get(self, url):
        """Mock HTTP GET responses."""
        class MockResponse:
            def __init__(self, url):
                self.url = url
                self.status_code = 200
                self.text = f"Response from {url}"
            
            def json(self):
                return {"url": self.url, "status": "ok"}
        
        return MockResponse(url)
    
    def test_integrated_workflow(self):
        # Generate unique test data
        unique_name = next(self.unique_id_gen)
        test_data = {
            'name': f'test_user_{unique_name}',
            'email': f'user_{unique_name}@example.com'
        }
        
        # Process data with filtering
        valid_data = filter_values(lambda v: '@' in v, test_data)
        self.assertIn('email', valid_data)
        
        # Transform data
        formatted_data = map_values(str.upper, 
                                  {'name': test_data['name']})
        
        # Make HTTP request (mocked)
        if self.requests:
            response = self.requests.get('http://api.example.com/users')
            self.assertEqual(response.status_code, 200)
            
            # Validate response with standalone assertion
            assert_that(response.json(), MatchesDict({
                'url': Contains('api.example.com'),
                'status': Equals('ok')
            }))