cpython/Lib/test/test_importlib/test_util.py

806 lines
31 KiB
Python

from . import util
abc = util.import_importlib('importlib.abc')
init = util.import_importlib('importlib')
machinery = util.import_importlib('importlib.machinery')
importlib_util = util.import_importlib('importlib.util')
import importlib.util
import os
import pathlib
import string
import sys
from test import support
import types
import unittest
import warnings
class DecodeSourceBytesTests:
source = "string ='ü'"
def test_ut8_default(self):
source_bytes = self.source.encode('utf-8')
self.assertEqual(self.util.decode_source(source_bytes), self.source)
def test_specified_encoding(self):
source = '# coding=latin-1\n' + self.source
source_bytes = source.encode('latin-1')
assert source_bytes != source.encode('utf-8')
self.assertEqual(self.util.decode_source(source_bytes), source)
def test_universal_newlines(self):
source = '\r\n'.join([self.source, self.source])
source_bytes = source.encode('utf-8')
self.assertEqual(self.util.decode_source(source_bytes),
'\n'.join([self.source, self.source]))
(Frozen_DecodeSourceBytesTests,
Source_DecodeSourceBytesTests
) = util.test_both(DecodeSourceBytesTests, util=importlib_util)
class ModuleFromSpecTests:
def test_no_create_module(self):
class Loader:
def exec_module(self, module):
pass
spec = self.machinery.ModuleSpec('test', Loader())
with self.assertRaises(ImportError):
module = self.util.module_from_spec(spec)
def test_create_module_returns_None(self):
class Loader(self.abc.Loader):
def create_module(self, spec):
return None
spec = self.machinery.ModuleSpec('test', Loader())
module = self.util.module_from_spec(spec)
self.assertIsInstance(module, types.ModuleType)
self.assertEqual(module.__name__, spec.name)
def test_create_module(self):
name = 'already set'
class CustomModule(types.ModuleType):
pass
class Loader(self.abc.Loader):
def create_module(self, spec):
module = CustomModule(spec.name)
module.__name__ = name
return module
spec = self.machinery.ModuleSpec('test', Loader())
module = self.util.module_from_spec(spec)
self.assertIsInstance(module, CustomModule)
self.assertEqual(module.__name__, name)
def test___name__(self):
spec = self.machinery.ModuleSpec('test', object())
module = self.util.module_from_spec(spec)
self.assertEqual(module.__name__, spec.name)
def test___spec__(self):
spec = self.machinery.ModuleSpec('test', object())
module = self.util.module_from_spec(spec)
self.assertEqual(module.__spec__, spec)
def test___loader__(self):
loader = object()
spec = self.machinery.ModuleSpec('test', loader)
module = self.util.module_from_spec(spec)
self.assertIs(module.__loader__, loader)
def test___package__(self):
spec = self.machinery.ModuleSpec('test.pkg', object())
module = self.util.module_from_spec(spec)
self.assertEqual(module.__package__, spec.parent)
def test___path__(self):
spec = self.machinery.ModuleSpec('test', object(), is_package=True)
module = self.util.module_from_spec(spec)
self.assertEqual(module.__path__, spec.submodule_search_locations)
def test___file__(self):
spec = self.machinery.ModuleSpec('test', object(), origin='some/path')
spec.has_location = True
module = self.util.module_from_spec(spec)
self.assertEqual(module.__file__, spec.origin)
def test___cached__(self):
spec = self.machinery.ModuleSpec('test', object())
spec.cached = 'some/path'
spec.has_location = True
module = self.util.module_from_spec(spec)
self.assertEqual(module.__cached__, spec.cached)
(Frozen_ModuleFromSpecTests,
Source_ModuleFromSpecTests
) = util.test_both(ModuleFromSpecTests, abc=abc, machinery=machinery,
util=importlib_util)
class ModuleForLoaderTests:
"""Tests for importlib.util.module_for_loader."""
@classmethod
def module_for_loader(cls, func):
with warnings.catch_warnings():
warnings.simplefilter('ignore', DeprecationWarning)
return cls.util.module_for_loader(func)
def test_warning(self):
# Should raise a PendingDeprecationWarning when used.
with warnings.catch_warnings():
warnings.simplefilter('error', DeprecationWarning)
with self.assertRaises(DeprecationWarning):
func = self.util.module_for_loader(lambda x: x)
def return_module(self, name):
fxn = self.module_for_loader(lambda self, module: module)
return fxn(self, name)
def raise_exception(self, name):
def to_wrap(self, module):
raise ImportError
fxn = self.module_for_loader(to_wrap)
try:
fxn(self, name)
except ImportError:
pass
def test_new_module(self):
# Test that when no module exists in sys.modules a new module is
# created.
module_name = 'a.b.c'
with util.uncache(module_name):
module = self.return_module(module_name)
self.assertIn(module_name, sys.modules)
self.assertIsInstance(module, types.ModuleType)
self.assertEqual(module.__name__, module_name)
def test_reload(self):
# Test that a module is reused if already in sys.modules.
class FakeLoader:
def is_package(self, name):
return True
@self.module_for_loader
def load_module(self, module):
return module
name = 'a.b.c'
module = types.ModuleType('a.b.c')
module.__loader__ = 42
module.__package__ = 42
with util.uncache(name):
sys.modules[name] = module
loader = FakeLoader()
returned_module = loader.load_module(name)
self.assertIs(returned_module, sys.modules[name])
self.assertEqual(module.__loader__, loader)
self.assertEqual(module.__package__, name)
def test_new_module_failure(self):
# Test that a module is removed from sys.modules if added but an
# exception is raised.
name = 'a.b.c'
with util.uncache(name):
self.raise_exception(name)
self.assertNotIn(name, sys.modules)
def test_reload_failure(self):
# Test that a failure on reload leaves the module in-place.
name = 'a.b.c'
module = types.ModuleType(name)
with util.uncache(name):
sys.modules[name] = module
self.raise_exception(name)
self.assertIs(module, sys.modules[name])
def test_decorator_attrs(self):
def fxn(self, module): pass
wrapped = self.module_for_loader(fxn)
self.assertEqual(wrapped.__name__, fxn.__name__)
self.assertEqual(wrapped.__qualname__, fxn.__qualname__)
def test_false_module(self):
# If for some odd reason a module is considered false, still return it
# from sys.modules.
class FalseModule(types.ModuleType):
def __bool__(self): return False
name = 'mod'
module = FalseModule(name)
with util.uncache(name):
self.assertFalse(module)
sys.modules[name] = module
given = self.return_module(name)
self.assertIs(given, module)
def test_attributes_set(self):
# __name__, __loader__, and __package__ should be set (when
# is_package() is defined; undefined implicitly tested elsewhere).
class FakeLoader:
def __init__(self, is_package):
self._pkg = is_package
def is_package(self, name):
return self._pkg
@self.module_for_loader
def load_module(self, module):
return module
name = 'pkg.mod'
with util.uncache(name):
loader = FakeLoader(False)
module = loader.load_module(name)
self.assertEqual(module.__name__, name)
self.assertIs(module.__loader__, loader)
self.assertEqual(module.__package__, 'pkg')
name = 'pkg.sub'
with util.uncache(name):
loader = FakeLoader(True)
module = loader.load_module(name)
self.assertEqual(module.__name__, name)
self.assertIs(module.__loader__, loader)
self.assertEqual(module.__package__, name)
(Frozen_ModuleForLoaderTests,
Source_ModuleForLoaderTests
) = util.test_both(ModuleForLoaderTests, util=importlib_util)
class SetPackageTests:
"""Tests for importlib.util.set_package."""
def verify(self, module, expect):
"""Verify the module has the expected value for __package__ after
passing through set_package."""
fxn = lambda: module
wrapped = self.util.set_package(fxn)
with warnings.catch_warnings():
warnings.simplefilter('ignore', DeprecationWarning)
wrapped()
self.assertTrue(hasattr(module, '__package__'))
self.assertEqual(expect, module.__package__)
def test_top_level(self):
# __package__ should be set to the empty string if a top-level module.
# Implicitly tests when package is set to None.
module = types.ModuleType('module')
module.__package__ = None
self.verify(module, '')
def test_package(self):
# Test setting __package__ for a package.
module = types.ModuleType('pkg')
module.__path__ = ['<path>']
module.__package__ = None
self.verify(module, 'pkg')
def test_submodule(self):
# Test __package__ for a module in a package.
module = types.ModuleType('pkg.mod')
module.__package__ = None
self.verify(module, 'pkg')
def test_setting_if_missing(self):
# __package__ should be set if it is missing.
module = types.ModuleType('mod')
if hasattr(module, '__package__'):
delattr(module, '__package__')
self.verify(module, '')
def test_leaving_alone(self):
# If __package__ is set and not None then leave it alone.
for value in (True, False):
module = types.ModuleType('mod')
module.__package__ = value
self.verify(module, value)
def test_decorator_attrs(self):
def fxn(module): pass
with warnings.catch_warnings():
warnings.simplefilter('ignore', DeprecationWarning)
wrapped = self.util.set_package(fxn)
self.assertEqual(wrapped.__name__, fxn.__name__)
self.assertEqual(wrapped.__qualname__, fxn.__qualname__)
(Frozen_SetPackageTests,
Source_SetPackageTests
) = util.test_both(SetPackageTests, util=importlib_util)
class SetLoaderTests:
"""Tests importlib.util.set_loader()."""
@property
def DummyLoader(self):
# Set DummyLoader on the class lazily.
class DummyLoader:
@self.util.set_loader
def load_module(self, module):
return self.module
self.__class__.DummyLoader = DummyLoader
return DummyLoader
def test_no_attribute(self):
loader = self.DummyLoader()
loader.module = types.ModuleType('blah')
try:
del loader.module.__loader__
except AttributeError:
pass
with warnings.catch_warnings():
warnings.simplefilter('ignore', DeprecationWarning)
self.assertEqual(loader, loader.load_module('blah').__loader__)
def test_attribute_is_None(self):
loader = self.DummyLoader()
loader.module = types.ModuleType('blah')
loader.module.__loader__ = None
with warnings.catch_warnings():
warnings.simplefilter('ignore', DeprecationWarning)
self.assertEqual(loader, loader.load_module('blah').__loader__)
def test_not_reset(self):
loader = self.DummyLoader()
loader.module = types.ModuleType('blah')
loader.module.__loader__ = 42
with warnings.catch_warnings():
warnings.simplefilter('ignore', DeprecationWarning)
self.assertEqual(42, loader.load_module('blah').__loader__)
(Frozen_SetLoaderTests,
Source_SetLoaderTests
) = util.test_both(SetLoaderTests, util=importlib_util)
class ResolveNameTests:
"""Tests importlib.util.resolve_name()."""
def test_absolute(self):
# bacon
self.assertEqual('bacon', self.util.resolve_name('bacon', None))
def test_absolute_within_package(self):
# bacon in spam
self.assertEqual('bacon', self.util.resolve_name('bacon', 'spam'))
def test_no_package(self):
# .bacon in ''
with self.assertRaises(ValueError):
self.util.resolve_name('.bacon', '')
def test_in_package(self):
# .bacon in spam
self.assertEqual('spam.eggs.bacon',
self.util.resolve_name('.bacon', 'spam.eggs'))
def test_other_package(self):
# ..bacon in spam.bacon
self.assertEqual('spam.bacon',
self.util.resolve_name('..bacon', 'spam.eggs'))
def test_escape(self):
# ..bacon in spam
with self.assertRaises(ValueError):
self.util.resolve_name('..bacon', 'spam')
(Frozen_ResolveNameTests,
Source_ResolveNameTests
) = util.test_both(ResolveNameTests, util=importlib_util)
class FindSpecTests:
class FakeMetaFinder:
@staticmethod
def find_spec(name, path=None, target=None): return name, path, target
def test_sys_modules(self):
name = 'some_mod'
with util.uncache(name):
module = types.ModuleType(name)
loader = 'a loader!'
spec = self.machinery.ModuleSpec(name, loader)
module.__loader__ = loader
module.__spec__ = spec
sys.modules[name] = module
found = self.util.find_spec(name)
self.assertEqual(found, spec)
def test_sys_modules_without___loader__(self):
name = 'some_mod'
with util.uncache(name):
module = types.ModuleType(name)
del module.__loader__
loader = 'a loader!'
spec = self.machinery.ModuleSpec(name, loader)
module.__spec__ = spec
sys.modules[name] = module
found = self.util.find_spec(name)
self.assertEqual(found, spec)
def test_sys_modules_spec_is_None(self):
name = 'some_mod'
with util.uncache(name):
module = types.ModuleType(name)
module.__spec__ = None
sys.modules[name] = module
with self.assertRaises(ValueError):
self.util.find_spec(name)
def test_sys_modules_loader_is_None(self):
name = 'some_mod'
with util.uncache(name):
module = types.ModuleType(name)
spec = self.machinery.ModuleSpec(name, None)
module.__spec__ = spec
sys.modules[name] = module
found = self.util.find_spec(name)
self.assertEqual(found, spec)
def test_sys_modules_spec_is_not_set(self):
name = 'some_mod'
with util.uncache(name):
module = types.ModuleType(name)
try:
del module.__spec__
except AttributeError:
pass
sys.modules[name] = module
with self.assertRaises(ValueError):
self.util.find_spec(name)
def test_success(self):
name = 'some_mod'
with util.uncache(name):
with util.import_state(meta_path=[self.FakeMetaFinder]):
self.assertEqual((name, None, None),
self.util.find_spec(name))
def test_nothing(self):
# None is returned upon failure to find a loader.
self.assertIsNone(self.util.find_spec('nevergoingtofindthismodule'))
def test_find_submodule(self):
name = 'spam'
subname = 'ham'
with util.temp_module(name, pkg=True) as pkg_dir:
fullname, _ = util.submodule(name, subname, pkg_dir)
spec = self.util.find_spec(fullname)
self.assertIsNot(spec, None)
self.assertIn(name, sorted(sys.modules))
self.assertNotIn(fullname, sorted(sys.modules))
# Ensure successive calls behave the same.
spec_again = self.util.find_spec(fullname)
self.assertEqual(spec_again, spec)
def test_find_submodule_parent_already_imported(self):
name = 'spam'
subname = 'ham'
with util.temp_module(name, pkg=True) as pkg_dir:
self.init.import_module(name)
fullname, _ = util.submodule(name, subname, pkg_dir)
spec = self.util.find_spec(fullname)
self.assertIsNot(spec, None)
self.assertIn(name, sorted(sys.modules))
self.assertNotIn(fullname, sorted(sys.modules))
# Ensure successive calls behave the same.
spec_again = self.util.find_spec(fullname)
self.assertEqual(spec_again, spec)
def test_find_relative_module(self):
name = 'spam'
subname = 'ham'
with util.temp_module(name, pkg=True) as pkg_dir:
fullname, _ = util.submodule(name, subname, pkg_dir)
relname = '.' + subname
spec = self.util.find_spec(relname, name)
self.assertIsNot(spec, None)
self.assertIn(name, sorted(sys.modules))
self.assertNotIn(fullname, sorted(sys.modules))
# Ensure successive calls behave the same.
spec_again = self.util.find_spec(fullname)
self.assertEqual(spec_again, spec)
def test_find_relative_module_missing_package(self):
name = 'spam'
subname = 'ham'
with util.temp_module(name, pkg=True) as pkg_dir:
fullname, _ = util.submodule(name, subname, pkg_dir)
relname = '.' + subname
with self.assertRaises(ValueError):
self.util.find_spec(relname)
self.assertNotIn(name, sorted(sys.modules))
self.assertNotIn(fullname, sorted(sys.modules))
(Frozen_FindSpecTests,
Source_FindSpecTests
) = util.test_both(FindSpecTests, init=init, util=importlib_util,
machinery=machinery)
class MagicNumberTests:
def test_length(self):
# Should be 4 bytes.
self.assertEqual(len(self.util.MAGIC_NUMBER), 4)
def test_incorporates_rn(self):
# The magic number uses \r\n to come out wrong when splitting on lines.
self.assertTrue(self.util.MAGIC_NUMBER.endswith(b'\r\n'))
(Frozen_MagicNumberTests,
Source_MagicNumberTests
) = util.test_both(MagicNumberTests, util=importlib_util)
class PEP3147Tests:
"""Tests of PEP 3147-related functions: cache_from_source and source_from_cache."""
tag = sys.implementation.cache_tag
@unittest.skipUnless(sys.implementation.cache_tag is not None,
'requires sys.implementation.cache_tag not be None')
def test_cache_from_source(self):
# Given the path to a .py file, return the path to its PEP 3147
# defined .pyc file (i.e. under __pycache__).
path = os.path.join('foo', 'bar', 'baz', 'qux.py')
expect = os.path.join('foo', 'bar', 'baz', '__pycache__',
'qux.{}.pyc'.format(self.tag))
self.assertEqual(self.util.cache_from_source(path, optimization=''),
expect)
def test_cache_from_source_no_cache_tag(self):
# No cache tag means NotImplementedError.
with support.swap_attr(sys.implementation, 'cache_tag', None):
with self.assertRaises(NotImplementedError):
self.util.cache_from_source('whatever.py')
def test_cache_from_source_no_dot(self):
# Directory with a dot, filename without dot.
path = os.path.join('foo.bar', 'file')
expect = os.path.join('foo.bar', '__pycache__',
'file{}.pyc'.format(self.tag))
self.assertEqual(self.util.cache_from_source(path, optimization=''),
expect)
def test_cache_from_source_debug_override(self):
# Given the path to a .py file, return the path to its PEP 3147/PEP 488
# defined .pyc file (i.e. under __pycache__).
path = os.path.join('foo', 'bar', 'baz', 'qux.py')
with warnings.catch_warnings():
warnings.simplefilter('ignore')
self.assertEqual(self.util.cache_from_source(path, False),
self.util.cache_from_source(path, optimization=1))
self.assertEqual(self.util.cache_from_source(path, True),
self.util.cache_from_source(path, optimization=''))
with warnings.catch_warnings():
warnings.simplefilter('error')
with self.assertRaises(DeprecationWarning):
self.util.cache_from_source(path, False)
with self.assertRaises(DeprecationWarning):
self.util.cache_from_source(path, True)
def test_cache_from_source_cwd(self):
path = 'foo.py'
expect = os.path.join('__pycache__', 'foo.{}.pyc'.format(self.tag))
self.assertEqual(self.util.cache_from_source(path, optimization=''),
expect)
def test_cache_from_source_override(self):
# When debug_override is not None, it can be any true-ish or false-ish
# value.
path = os.path.join('foo', 'bar', 'baz.py')
# However if the bool-ishness can't be determined, the exception
# propagates.
class Bearish:
def __bool__(self): raise RuntimeError
with warnings.catch_warnings():
warnings.simplefilter('ignore')
self.assertEqual(self.util.cache_from_source(path, []),
self.util.cache_from_source(path, optimization=1))
self.assertEqual(self.util.cache_from_source(path, [17]),
self.util.cache_from_source(path, optimization=''))
with self.assertRaises(RuntimeError):
self.util.cache_from_source('/foo/bar/baz.py', Bearish())
def test_cache_from_source_optimization_empty_string(self):
# Setting 'optimization' to '' leads to no optimization tag (PEP 488).
path = 'foo.py'
expect = os.path.join('__pycache__', 'foo.{}.pyc'.format(self.tag))
self.assertEqual(self.util.cache_from_source(path, optimization=''),
expect)
def test_cache_from_source_optimization_None(self):
# Setting 'optimization' to None uses the interpreter's optimization.
# (PEP 488)
path = 'foo.py'
optimization_level = sys.flags.optimize
almost_expect = os.path.join('__pycache__', 'foo.{}'.format(self.tag))
if optimization_level == 0:
expect = almost_expect + '.pyc'
elif optimization_level <= 2:
expect = almost_expect + '.opt-{}.pyc'.format(optimization_level)
else:
msg = '{!r} is a non-standard optimization level'.format(optimization_level)
self.skipTest(msg)
self.assertEqual(self.util.cache_from_source(path, optimization=None),
expect)
def test_cache_from_source_optimization_set(self):
# The 'optimization' parameter accepts anything that has a string repr
# that passes str.alnum().
path = 'foo.py'
valid_characters = string.ascii_letters + string.digits
almost_expect = os.path.join('__pycache__', 'foo.{}'.format(self.tag))
got = self.util.cache_from_source(path, optimization=valid_characters)
# Test all valid characters are accepted.
self.assertEqual(got,
almost_expect + '.opt-{}.pyc'.format(valid_characters))
# str() should be called on argument.
self.assertEqual(self.util.cache_from_source(path, optimization=42),
almost_expect + '.opt-42.pyc')
# Invalid characters raise ValueError.
with self.assertRaises(ValueError):
self.util.cache_from_source(path, optimization='path/is/bad')
def test_cache_from_source_debug_override_optimization_both_set(self):
# Can only set one of the optimization-related parameters.
with warnings.catch_warnings():
warnings.simplefilter('ignore')
with self.assertRaises(TypeError):
self.util.cache_from_source('foo.py', False, optimization='')
@unittest.skipUnless(os.sep == '\\' and os.altsep == '/',
'test meaningful only where os.altsep is defined')
def test_sep_altsep_and_sep_cache_from_source(self):
# Windows path and PEP 3147 where sep is right of altsep.
self.assertEqual(
self.util.cache_from_source('\\foo\\bar\\baz/qux.py', optimization=''),
'\\foo\\bar\\baz\\__pycache__\\qux.{}.pyc'.format(self.tag))
@unittest.skipUnless(sys.implementation.cache_tag is not None,
'requires sys.implementation.cache_tag not be None')
def test_source_from_cache_path_like_arg(self):
path = pathlib.PurePath('foo', 'bar', 'baz', 'qux.py')
expect = os.path.join('foo', 'bar', 'baz', '__pycache__',
'qux.{}.pyc'.format(self.tag))
self.assertEqual(self.util.cache_from_source(path, optimization=''),
expect)
@unittest.skipUnless(sys.implementation.cache_tag is not None,
'requires sys.implementation.cache_tag to not be '
'None')
def test_source_from_cache(self):
# Given the path to a PEP 3147 defined .pyc file, return the path to
# its source. This tests the good path.
path = os.path.join('foo', 'bar', 'baz', '__pycache__',
'qux.{}.pyc'.format(self.tag))
expect = os.path.join('foo', 'bar', 'baz', 'qux.py')
self.assertEqual(self.util.source_from_cache(path), expect)
def test_source_from_cache_no_cache_tag(self):
# If sys.implementation.cache_tag is None, raise NotImplementedError.
path = os.path.join('blah', '__pycache__', 'whatever.pyc')
with support.swap_attr(sys.implementation, 'cache_tag', None):
with self.assertRaises(NotImplementedError):
self.util.source_from_cache(path)
def test_source_from_cache_bad_path(self):
# When the path to a pyc file is not in PEP 3147 format, a ValueError
# is raised.
self.assertRaises(
ValueError, self.util.source_from_cache, '/foo/bar/bazqux.pyc')
def test_source_from_cache_no_slash(self):
# No slashes at all in path -> ValueError
self.assertRaises(
ValueError, self.util.source_from_cache, 'foo.cpython-32.pyc')
def test_source_from_cache_too_few_dots(self):
# Too few dots in final path component -> ValueError
self.assertRaises(
ValueError, self.util.source_from_cache, '__pycache__/foo.pyc')
def test_source_from_cache_too_many_dots(self):
with self.assertRaises(ValueError):
self.util.source_from_cache(
'__pycache__/foo.cpython-32.opt-1.foo.pyc')
def test_source_from_cache_not_opt(self):
# Non-`opt-` path component -> ValueError
self.assertRaises(
ValueError, self.util.source_from_cache,
'__pycache__/foo.cpython-32.foo.pyc')
def test_source_from_cache_no__pycache__(self):
# Another problem with the path -> ValueError
self.assertRaises(
ValueError, self.util.source_from_cache,
'/foo/bar/foo.cpython-32.foo.pyc')
def test_source_from_cache_optimized_bytecode(self):
# Optimized bytecode is not an issue.
path = os.path.join('__pycache__', 'foo.{}.opt-1.pyc'.format(self.tag))
self.assertEqual(self.util.source_from_cache(path), 'foo.py')
def test_source_from_cache_missing_optimization(self):
# An empty optimization level is a no-no.
path = os.path.join('__pycache__', 'foo.{}.opt-.pyc'.format(self.tag))
with self.assertRaises(ValueError):
self.util.source_from_cache(path)
@unittest.skipUnless(sys.implementation.cache_tag is not None,
'requires sys.implementation.cache_tag to not be '
'None')
def test_source_from_cache_path_like_arg(self):
path = pathlib.PurePath('foo', 'bar', 'baz', '__pycache__',
'qux.{}.pyc'.format(self.tag))
expect = os.path.join('foo', 'bar', 'baz', 'qux.py')
self.assertEqual(self.util.source_from_cache(path), expect)
(Frozen_PEP3147Tests,
Source_PEP3147Tests
) = util.test_both(PEP3147Tests, util=importlib_util)
class MagicNumberTests(unittest.TestCase):
"""
Test release compatibility issues relating to importlib
"""
@unittest.skipUnless(
sys.version_info.releaselevel in ('final', 'release'),
'only applies to candidate or final python release levels'
)
def test_magic_number(self):
"""
Each python minor release should generally have a MAGIC_NUMBER
that does not change once the release reaches candidate status.
Once a release reaches candidate status, the value of the constant
EXPECTED_MAGIC_NUMBER in this test should be changed.
This test will then check that the actual MAGIC_NUMBER matches
the expected value for the release.
In exceptional cases, it may be required to change the MAGIC_NUMBER
for a maintenance release. In this case the change should be
discussed in python-dev. If a change is required, community
stakeholders such as OS package maintainers must be notified
in advance. Such exceptional releases will then require an
adjustment to this test case.
"""
EXPECTED_MAGIC_NUMBER = 3379
actual = int.from_bytes(importlib.util.MAGIC_NUMBER[:2], 'little')
msg = (
"To avoid breaking backwards compatibility with cached bytecode "
"files that can't be automatically regenerated by the current "
"user, candidate and final releases require the current "
"importlib.util.MAGIC_NUMBER to match the expected "
"magic number in this test. Set the expected "
"magic number in this test to the current MAGIC_NUMBER to "
"continue with the release.\n\n"
"Changing the MAGIC_NUMBER for a maintenance release "
"requires discussion in python-dev and notification of "
"community stakeholders."
)
self.assertEqual(EXPECTED_MAGIC_NUMBER, actual, msg)
if __name__ == '__main__':
unittest.main()