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Introduce importlib.abc. The module contains various ABCs related to imports
(mostly stuff specified by PEP 302). There are two ABCs, PyLoader and PyPycLoader, which help with implementing source and source/bytecode loaders by implementing load_module in terms of other methods. This removes a lot of gritty details loaders typically have to worry about.
This commit is contained in:
Brett Cannon
parent
aa1c8d8899
commit
2a922ed6ad
9 changed files with 739 additions and 171 deletions
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import importlib
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from .. import abc
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from . import util as source_util
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import imp
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import os
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import py_compile
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import sys
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import unittest
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class SimpleTest(unittest.TestCase):
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"""Should have no issue importing a source module [basic]. And if there is
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a syntax error, it should raise a SyntaxError [syntax error].
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"""
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# [basic]
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def test_module(self):
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with source_util.create_modules('_temp') as mapping:
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loader = importlib.PyPycFileLoader('_temp', mapping['_temp'], False)
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module = loader.load_module('_temp')
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self.assert_('_temp' in sys.modules)
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check = {'__name__': '_temp', '__file__': mapping['_temp'],
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'__package__': ''}
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for attr, value in check.items():
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self.assertEqual(getattr(module, attr), value)
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def test_package(self):
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with source_util.create_modules('_pkg.__init__') as mapping:
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loader = importlib.PyPycFileLoader('_pkg', mapping['_pkg.__init__'],
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True)
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module = loader.load_module('_pkg')
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self.assert_('_pkg' in sys.modules)
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check = {'__name__': '_pkg', '__file__': mapping['_pkg.__init__'],
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'__path__': [os.path.dirname(mapping['_pkg.__init__'])],
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'__package__': '_pkg'}
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for attr, value in check.items():
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self.assertEqual(getattr(module, attr), value)
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def test_lacking_parent(self):
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with source_util.create_modules('_pkg.__init__', '_pkg.mod')as mapping:
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loader = importlib.PyPycFileLoader('_pkg.mod', mapping['_pkg.mod'],
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False)
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module = loader.load_module('_pkg.mod')
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self.assert_('_pkg.mod' in sys.modules)
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check = {'__name__': '_pkg.mod', '__file__': mapping['_pkg.mod'],
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'__package__': '_pkg'}
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for attr, value in check.items():
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self.assertEqual(getattr(module, attr), value)
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def fake_mtime(self, fxn):
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"""Fake mtime to always be higher than expected."""
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return lambda name: fxn(name) + 1
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def test_module_reuse(self):
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with source_util.create_modules('_temp') as mapping:
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loader = importlib.PyPycFileLoader('_temp', mapping['_temp'], False)
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module = loader.load_module('_temp')
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module_id = id(module)
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module_dict_id = id(module.__dict__)
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with open(mapping['_temp'], 'w') as file:
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file.write("testing_var = 42\n")
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# For filesystems where the mtime is only to a second granularity,
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# everything that has happened above can be too fast;
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# force an mtime on the source that is guaranteed to be different
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# than the original mtime.
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loader.source_mtime = self.fake_mtime(loader.source_mtime)
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module = loader.load_module('_temp')
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self.assert_('testing_var' in module.__dict__,
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"'testing_var' not in "
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"{0}".format(list(module.__dict__.keys())))
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self.assertEqual(module, sys.modules['_temp'])
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self.assertEqual(id(module), module_id)
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self.assertEqual(id(module.__dict__), module_dict_id)
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def test_state_after_failure(self):
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# A failed reload should leave the original module intact.
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attributes = ('__file__', '__path__', '__package__')
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value = '<test>'
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name = '_temp'
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with source_util.create_modules(name) as mapping:
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orig_module = imp.new_module(name)
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for attr in attributes:
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setattr(orig_module, attr, value)
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with open(mapping[name], 'w') as file:
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file.write('+++ bad syntax +++')
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loader = importlib.PyPycFileLoader('_temp', mapping['_temp'], False)
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self.assertRaises(SyntaxError, loader.load_module, name)
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for attr in attributes:
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self.assertEqual(getattr(orig_module, attr), value)
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# [syntax error]
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def test_bad_syntax(self):
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with source_util.create_modules('_temp') as mapping:
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with open(mapping['_temp'], 'w') as file:
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file.write('=')
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loader = importlib.PyPycFileLoader('_temp', mapping['_temp'], False)
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self.assertRaises(SyntaxError, loader.load_module, '_temp')
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self.assert_('_temp' not in sys.modules)
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class DontWriteBytecodeTest(unittest.TestCase):
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"""If sys.dont_write_bytcode is true then no bytecode should be created."""
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def tearDown(self):
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sys.dont_write_bytecode = False
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@source_util.writes_bytecode
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def run_test(self, assertion):
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with source_util.create_modules('_temp') as mapping:
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loader = importlib.PyPycFileLoader('_temp', mapping['_temp'], False)
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loader.load_module('_temp')
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bytecode_path = source_util.bytecode_path(mapping['_temp'])
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assertion(bytecode_path)
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def test_bytecode_written(self):
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fxn = lambda bc_path: self.assert_(os.path.exists(bc_path))
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self.run_test(fxn)
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def test_bytecode_not_written(self):
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sys.dont_write_bytecode = True
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fxn = lambda bc_path: self.assert_(not os.path.exists(bc_path))
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self.run_test(fxn)
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class BadDataTest(unittest.TestCase):
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"""If the bytecode has a magic number that does not match the
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interpreters', ImportError is raised [bad magic]. The timestamp can have
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any value. And bad marshal data raises ValueError.
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"""
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# [bad magic]
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def test_bad_magic(self):
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with source_util.create_modules('_temp') as mapping:
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py_compile.compile(mapping['_temp'])
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os.unlink(mapping['_temp'])
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bytecode_path = source_util.bytecode_path(mapping['_temp'])
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with open(bytecode_path, 'r+b') as file:
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file.seek(0)
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file.write(b'\x00\x00\x00\x00')
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loader = importlib.PyPycFileLoader('_temp', mapping['_temp'], False)
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self.assertRaises(ImportError, loader.load_module, '_temp')
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self.assert_('_temp' not in sys.modules)
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class SourceBytecodeInteraction(unittest.TestCase):
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"""When both source and bytecode are present, certain rules dictate which
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version of the code takes precedent. All things being equal, the bytecode
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is used with the value of __file__ set to the source [basic top-level],
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[basic package], [basic sub-module], [basic sub-package].
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"""
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def import_(self, file, module, *, pkg=False):
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loader = importlib.PyPycFileLoader(module, file, pkg)
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return loader.load_module(module)
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def run_test(self, test, *create, pkg=False):
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create += (test,)
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with source_util.create_modules(*create) as mapping:
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for name in create:
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py_compile.compile(mapping[name])
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if pkg:
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import_name = test.rsplit('.', 1)[0]
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else:
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import_name = test
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loader = importlib.PyPycFileLoader(import_name, mapping[test], pkg)
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# Because some platforms only have a granularity to the second for
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# atime you can't check the physical files. Instead just make it an
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# exception trigger if source was read.
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loader.get_source = lambda self, x: 42
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module = loader.load_module(import_name)
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self.assertEqual(module.__file__, mapping[name])
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self.assert_(import_name in sys.modules)
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self.assertEqual(id(module), id(sys.modules[import_name]))
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# [basic top-level]
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def test_basic_top_level(self):
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self.run_test('top_level')
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# [basic package]
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def test_basic_package(self):
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self.run_test('pkg.__init__', pkg=True)
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# [basic sub-module]
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def test_basic_sub_module(self):
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self.run_test('pkg.sub', 'pkg.__init__')
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# [basic sub-package]
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def test_basic_sub_package(self):
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self.run_test('pkg.sub.__init__', 'pkg.__init__', pkg=True)
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class BadBytecodeTest(unittest.TestCase):
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"""But there are several things about the bytecode which might lead to the
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source being preferred. If the magic number differs from what the
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interpreter uses, then the source is used with the bytecode regenerated.
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If the timestamp is older than the modification time for the source then
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the bytecode is not used [bad timestamp].
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But if the marshal data is bad, even if the magic number and timestamp
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work, a ValueError is raised and the source is not used [bad marshal].
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"""
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def import_(self, file, module_name):
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loader = importlib.PyPycFileLoader(module_name, file, False)
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module = loader.load_module(module_name)
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self.assert_(module_name in sys.modules)
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# [bad magic]
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@source_util.writes_bytecode
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def test_bad_magic(self):
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with source_util.create_modules('_temp') as mapping:
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py_compile.compile(mapping['_temp'])
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bytecode_path = source_util.bytecode_path(mapping['_temp'])
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with open(bytecode_path, 'r+b') as bytecode_file:
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bytecode_file.seek(0)
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bytecode_file.write(b'\x00\x00\x00\x00')
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self.import_(mapping['_temp'], '_temp')
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with open(bytecode_path, 'rb') as bytecode_file:
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self.assertEqual(bytecode_file.read(4), imp.get_magic())
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# [bad timestamp]
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@source_util.writes_bytecode
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def test_bad_bytecode(self):
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zeros = b'\x00\x00\x00\x00'
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with source_util.create_modules('_temp') as mapping:
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py_compile.compile(mapping['_temp'])
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bytecode_path = source_util.bytecode_path(mapping['_temp'])
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with open(bytecode_path, 'r+b') as bytecode_file:
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bytecode_file.seek(4)
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bytecode_file.write(zeros)
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self.import_(mapping['_temp'], '_temp')
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source_mtime = os.path.getmtime(mapping['_temp'])
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source_timestamp = importlib._w_long(source_mtime)
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with open(bytecode_path, 'rb') as bytecode_file:
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bytecode_file.seek(4)
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self.assertEqual(bytecode_file.read(4), source_timestamp)
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# [bad marshal]
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def test_bad_marshal(self):
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with source_util.create_modules('_temp') as mapping:
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bytecode_path = source_util.bytecode_path(mapping['_temp'])
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source_mtime = os.path.getmtime(mapping['_temp'])
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source_timestamp = importlib._w_long(source_mtime)
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with open(bytecode_path, 'wb') as bytecode_file:
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bytecode_file.write(imp.get_magic())
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bytecode_file.write(source_timestamp)
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bytecode_file.write(b'AAAA')
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self.assertRaises(ValueError, self.import_, mapping['_temp'],
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'_temp')
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self.assert_('_temp' not in sys.modules)
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def test_main():
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from test.support import run_unittest
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run_unittest(SimpleTest, DontWriteBytecodeTest, BadDataTest,
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SourceBytecodeInteraction, BadBytecodeTest)
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if __name__ == '__main__':
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test_main()
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