Issue #17636: Circular imports involving relative imports are now supported.

1 files changed, 0 insertions, 1073 deletions

diff --git a/Lib/test/test_import.py b/Lib/test/test_import.py
deleted file mode 100644
index b4842c5..0000000
--- a/Lib/test/test_import.py
+++ /dev/null
@@ -1,1073 +0,0 @@
-# We import importlib *ASAP* in order to test #15386
-import importlib
-import importlib.util
-from importlib._bootstrap import _get_sourcefile
-import builtins
-import marshal
-import os
-import platform
-import py_compile
-import random
-import stat
-import sys
-import unittest
-import unittest.mock as mock
-import textwrap
-import errno
-import shutil
-import contextlib
-
-import test.support
-from test.support import (
-    EnvironmentVarGuard, TESTFN, check_warnings, forget, is_jython,
-    make_legacy_pyc, rmtree, run_unittest, swap_attr, swap_item, temp_umask,
-    unlink, unload, create_empty_file, cpython_only, TESTFN_UNENCODABLE)
-from test import script_helper
-
-
-skip_if_dont_write_bytecode = unittest.skipIf(
-        sys.dont_write_bytecode,
-        "test meaningful only when writing bytecode")
-
-def remove_files(name):
-    for f in (name + ".py",
-              name + ".pyc",
-              name + ".pyo",
-              name + ".pyw",
-              name + "$py.class"):
-        unlink(f)
-    rmtree('__pycache__')
-
-
-@contextlib.contextmanager
-def _ready_to_import(name=None, source=""):
-    # sets up a temporary directory and removes it
-    # creates the module file
-    # temporarily clears the module from sys.modules (if any)
-    # reverts or removes the module when cleaning up
-    name = name or "spam"
-    with script_helper.temp_dir() as tempdir:
-        path = script_helper.make_script(tempdir, name, source)
-        old_module = sys.modules.pop(name, None)
-        try:
-            sys.path.insert(0, tempdir)
-            yield name, path
-            sys.path.remove(tempdir)
-        finally:
-            if old_module is not None:
-                sys.modules[name] = old_module
-            elif name in sys.modules:
-                del sys.modules[name]
-
-
-class ImportTests(unittest.TestCase):
-
-    def setUp(self):
-        remove_files(TESTFN)
-        importlib.invalidate_caches()
-
-    def tearDown(self):
-        unload(TESTFN)
-
-    def test_case_sensitivity(self):
-        # Brief digression to test that import is case-sensitive:  if we got
-        # this far, we know for sure that "random" exists.
-        with self.assertRaises(ImportError):
-            import RAnDoM
-
-    def test_double_const(self):
-        # Another brief digression to test the accuracy of manifest float
-        # constants.
-        from test import double_const  # don't blink -- that *was* the test
-
-    def test_import(self):
-        def test_with_extension(ext):
-            # The extension is normally ".py", perhaps ".pyw".
-            source = TESTFN + ext
-            pyo = TESTFN + ".pyo"
-            if is_jython:
-                pyc = TESTFN + "$py.class"
-            else:
-                pyc = TESTFN + ".pyc"
-
-            with open(source, "w") as f:
-                print("# This tests Python's ability to import a",
-                      ext, "file.", file=f)
-                a = random.randrange(1000)
-                b = random.randrange(1000)
-                print("a =", a, file=f)
-                print("b =", b, file=f)
-
-            if TESTFN in sys.modules:
-                del sys.modules[TESTFN]
-            importlib.invalidate_caches()
-            try:
-                try:
-                    mod = __import__(TESTFN)
-                except ImportError as err:
-                    self.fail("import from %s failed: %s" % (ext, err))
-
-                self.assertEqual(mod.a, a,
-                    "module loaded (%s) but contents invalid" % mod)
-                self.assertEqual(mod.b, b,
-                    "module loaded (%s) but contents invalid" % mod)
-            finally:
-                forget(TESTFN)
-                unlink(source)
-                unlink(pyc)
-                unlink(pyo)
-
-        sys.path.insert(0, os.curdir)
-        try:
-            test_with_extension(".py")
-            if sys.platform.startswith("win"):
-                for ext in [".PY", ".Py", ".pY", ".pyw", ".PYW", ".pYw"]:
-                    test_with_extension(ext)
-        finally:
-            del sys.path[0]
-
-    def test_module_with_large_stack(self, module='longlist'):
-        # Regression test for http://bugs.python.org/issue561858.
-        filename = module + '.py'
-
-        # Create a file with a list of 65000 elements.
-        with open(filename, 'w') as f:
-            f.write('d = [\n')
-            for i in range(65000):
-                f.write('"",\n')
-            f.write(']')
-
-        try:
-            # Compile & remove .py file; we only need .pyc (or .pyo).
-            # Bytecode must be relocated from the PEP 3147 bytecode-only location.
-            py_compile.compile(filename)
-        finally:
-            unlink(filename)
-
-        # Need to be able to load from current dir.
-        sys.path.append('')
-        importlib.invalidate_caches()
-
-        namespace = {}
-        try:
-            make_legacy_pyc(filename)
-            # This used to crash.
-            exec('import ' + module, None, namespace)
-        finally:
-            # Cleanup.
-            del sys.path[-1]
-            unlink(filename + 'c')
-            unlink(filename + 'o')
-
-            # Remove references to the module (unload the module)
-            namespace.clear()
-            try:
-                del sys.modules[module]
-            except KeyError:
-                pass
-
-    def test_failing_import_sticks(self):
-        source = TESTFN + ".py"
-        with open(source, "w") as f:
-            print("a = 1/0", file=f)
-
-        # New in 2.4, we shouldn't be able to import that no matter how often
-        # we try.
-        sys.path.insert(0, os.curdir)
-        importlib.invalidate_caches()
-        if TESTFN in sys.modules:
-            del sys.modules[TESTFN]
-        try:
-            for i in [1, 2, 3]:
-                self.assertRaises(ZeroDivisionError, __import__, TESTFN)
-                self.assertNotIn(TESTFN, sys.modules,
-                                 "damaged module in sys.modules on %i try" % i)
-        finally:
-            del sys.path[0]
-            remove_files(TESTFN)
-
-    def test_import_name_binding(self):
-        # import x.y.z binds x in the current namespace
-        import test as x
-        import test.support
-        self.assertIs(x, test, x.__name__)
-        self.assertTrue(hasattr(test.support, "__file__"))
-
-        # import x.y.z as w binds z as w
-        import test.support as y
-        self.assertIs(y, test.support, y.__name__)
-
-    def test_failing_reload(self):
-        # A failing reload should leave the module object in sys.modules.
-        source = TESTFN + os.extsep + "py"
-        with open(source, "w") as f:
-            f.write("a = 1\nb=2\n")
-
-        sys.path.insert(0, os.curdir)
-        try:
-            mod = __import__(TESTFN)
-            self.assertIn(TESTFN, sys.modules)
-            self.assertEqual(mod.a, 1, "module has wrong attribute values")
-            self.assertEqual(mod.b, 2, "module has wrong attribute values")
-
-            # On WinXP, just replacing the .py file wasn't enough to
-            # convince reload() to reparse it.  Maybe the timestamp didn't
-            # move enough.  We force it to get reparsed by removing the
-            # compiled file too.
-            remove_files(TESTFN)
-
-            # Now damage the module.
-            with open(source, "w") as f:
-                f.write("a = 10\nb=20//0\n")
-
-            self.assertRaises(ZeroDivisionError, importlib.reload, mod)
-            # But we still expect the module to be in sys.modules.
-            mod = sys.modules.get(TESTFN)
-            self.assertIsNotNone(mod, "expected module to be in sys.modules")
-
-            # We should have replaced a w/ 10, but the old b value should
-            # stick.
-            self.assertEqual(mod.a, 10, "module has wrong attribute values")
-            self.assertEqual(mod.b, 2, "module has wrong attribute values")
-
-        finally:
-            del sys.path[0]
-            remove_files(TESTFN)
-            unload(TESTFN)
-
-    @skip_if_dont_write_bytecode
-    def test_file_to_source(self):
-        # check if __file__ points to the source file where available
-        source = TESTFN + ".py"
-        with open(source, "w") as f:
-            f.write("test = None\n")
-
-        sys.path.insert(0, os.curdir)
-        try:
-            mod = __import__(TESTFN)
-            self.assertTrue(mod.__file__.endswith('.py'))
-            os.remove(source)
-            del sys.modules[TESTFN]
-            make_legacy_pyc(source)
-            importlib.invalidate_caches()
-            mod = __import__(TESTFN)
-            base, ext = os.path.splitext(mod.__file__)
-            self.assertIn(ext, ('.pyc', '.pyo'))
-        finally:
-            del sys.path[0]
-            remove_files(TESTFN)
-            if TESTFN in sys.modules:
-                del sys.modules[TESTFN]
-
-    def test_import_by_filename(self):
-        path = os.path.abspath(TESTFN)
-        encoding = sys.getfilesystemencoding()
-        try:
-            path.encode(encoding)
-        except UnicodeEncodeError:
-            self.skipTest('path is not encodable to {}'.format(encoding))
-        with self.assertRaises(ImportError) as c:
-            __import__(path)
-
-    def test_import_in_del_does_not_crash(self):
-        # Issue 4236
-        testfn = script_helper.make_script('', TESTFN, textwrap.dedent("""\
-            import sys
-            class C:
-               def __del__(self):
-                  import importlib
-            sys.argv.insert(0, C())
-            """))
-        script_helper.assert_python_ok(testfn)
-
-    def test_timestamp_overflow(self):
-        # A modification timestamp larger than 2**32 should not be a problem
-        # when importing a module (issue #11235).
-        sys.path.insert(0, os.curdir)
-        try:
-            source = TESTFN + ".py"
-            compiled = importlib.util.cache_from_source(source)
-            with open(source, 'w') as f:
-                pass
-            try:
-                os.utime(source, (2 ** 33 - 5, 2 ** 33 - 5))
-            except OverflowError:
-                self.skipTest("cannot set modification time to large integer")
-            except OSError as e:
-                if e.errno != getattr(errno, 'EOVERFLOW', None):
-                    raise
-                self.skipTest("cannot set modification time to large integer ({})".format(e))
-            __import__(TESTFN)
-            # The pyc file was created.
-            os.stat(compiled)
-        finally:
-            del sys.path[0]
-            remove_files(TESTFN)
-
-    def test_bogus_fromlist(self):
-        try:
-            __import__('http', fromlist=['blah'])
-        except ImportError:
-            self.fail("fromlist must allow bogus names")
-
-    @cpython_only
-    def test_delete_builtins_import(self):
-        args = ["-c", "del __builtins__.__import__; import os"]
-        popen = script_helper.spawn_python(*args)
-        stdout, stderr = popen.communicate()
-        self.assertIn(b"ImportError", stdout)
-
-    def test_from_import_message_for_nonexistent_module(self):
-        with self.assertRaisesRegex(ImportError, "^No module named 'bogus'"):
-            from bogus import foo
-
-    def test_from_import_message_for_existing_module(self):
-        with self.assertRaisesRegex(ImportError, "^cannot import name 'bogus'"):
-            from re import bogus
-
-
-@skip_if_dont_write_bytecode
-class FilePermissionTests(unittest.TestCase):
-    # tests for file mode on cached .pyc/.pyo files
-
-    @unittest.skipUnless(os.name == 'posix',
-                         "test meaningful only on posix systems")
-    def test_creation_mode(self):
-        mask = 0o022
-        with temp_umask(mask), _ready_to_import() as (name, path):
-            cached_path = importlib.util.cache_from_source(path)
-            module = __import__(name)
-            if not os.path.exists(cached_path):
-                self.fail("__import__ did not result in creation of "
-                          "either a .pyc or .pyo file")
-            stat_info = os.stat(cached_path)
-
-        # Check that the umask is respected, and the executable bits
-        # aren't set.
-        self.assertEqual(oct(stat.S_IMODE(stat_info.st_mode)),
-                         oct(0o666 & ~mask))
-
-    @unittest.skipUnless(os.name == 'posix',
-                         "test meaningful only on posix systems")
-    def test_cached_mode_issue_2051(self):
-        # permissions of .pyc should match those of .py, regardless of mask
-        mode = 0o600
-        with temp_umask(0o022), _ready_to_import() as (name, path):
-            cached_path = importlib.util.cache_from_source(path)
-            os.chmod(path, mode)
-            __import__(name)
-            if not os.path.exists(cached_path):
-                self.fail("__import__ did not result in creation of "
-                          "either a .pyc or .pyo file")
-            stat_info = os.stat(cached_path)
-
-        self.assertEqual(oct(stat.S_IMODE(stat_info.st_mode)), oct(mode))
-
-    @unittest.skipUnless(os.name == 'posix',
-                         "test meaningful only on posix systems")
-    def test_cached_readonly(self):
-        mode = 0o400
-        with temp_umask(0o022), _ready_to_import() as (name, path):
-            cached_path = importlib.util.cache_from_source(path)
-            os.chmod(path, mode)
-            __import__(name)
-            if not os.path.exists(cached_path):
-                self.fail("__import__ did not result in creation of "
-                          "either a .pyc or .pyo file")
-            stat_info = os.stat(cached_path)
-
-        expected = mode | 0o200 # Account for fix for issue #6074
-        self.assertEqual(oct(stat.S_IMODE(stat_info.st_mode)), oct(expected))
-
-    def test_pyc_always_writable(self):
-        # Initially read-only .pyc files on Windows used to cause problems
-        # with later updates, see issue #6074 for details
-        with _ready_to_import() as (name, path):
-            # Write a Python file, make it read-only and import it
-            with open(path, 'w') as f:
-                f.write("x = 'original'\n")
-            # Tweak the mtime of the source to ensure pyc gets updated later
-            s = os.stat(path)
-            os.utime(path, (s.st_atime, s.st_mtime-100000000))
-            os.chmod(path, 0o400)
-            m = __import__(name)
-            self.assertEqual(m.x, 'original')
-            # Change the file and then reimport it
-            os.chmod(path, 0o600)
-            with open(path, 'w') as f:
-                f.write("x = 'rewritten'\n")
-            unload(name)
-            importlib.invalidate_caches()
-            m = __import__(name)
-            self.assertEqual(m.x, 'rewritten')
-            # Now delete the source file and check the pyc was rewritten
-            unlink(path)
-            unload(name)
-            importlib.invalidate_caches()
-            if __debug__:
-                bytecode_only = path + "c"
-            else:
-                bytecode_only = path + "o"
-            os.rename(importlib.util.cache_from_source(path), bytecode_only)
-            m = __import__(name)
-            self.assertEqual(m.x, 'rewritten')
-
-
-class PycRewritingTests(unittest.TestCase):
-    # Test that the `co_filename` attribute on code objects always points
-    # to the right file, even when various things happen (e.g. both the .py
-    # and the .pyc file are renamed).
-
-    module_name = "unlikely_module_name"
-    module_source = """
-import sys
-code_filename = sys._getframe().f_code.co_filename
-module_filename = __file__
-constant = 1
-def func():
-    pass
-func_filename = func.__code__.co_filename
-"""
-    dir_name = os.path.abspath(TESTFN)
-    file_name = os.path.join(dir_name, module_name) + os.extsep + "py"
-    compiled_name = importlib.util.cache_from_source(file_name)
-
-    def setUp(self):
-        self.sys_path = sys.path[:]
-        self.orig_module = sys.modules.pop(self.module_name, None)
-        os.mkdir(self.dir_name)
-        with open(self.file_name, "w") as f:
-            f.write(self.module_source)
-        sys.path.insert(0, self.dir_name)
-        importlib.invalidate_caches()
-
-    def tearDown(self):
-        sys.path[:] = self.sys_path
-        if self.orig_module is not None:
-            sys.modules[self.module_name] = self.orig_module
-        else:
-            unload(self.module_name)
-        unlink(self.file_name)
-        unlink(self.compiled_name)
-        rmtree(self.dir_name)
-
-    def import_module(self):
-        ns = globals()
-        __import__(self.module_name, ns, ns)
-        return sys.modules[self.module_name]
-
-    def test_basics(self):
-        mod = self.import_module()
-        self.assertEqual(mod.module_filename, self.file_name)
-        self.assertEqual(mod.code_filename, self.file_name)
-        self.assertEqual(mod.func_filename, self.file_name)
-        del sys.modules[self.module_name]
-        mod = self.import_module()
-        self.assertEqual(mod.module_filename, self.file_name)
-        self.assertEqual(mod.code_filename, self.file_name)
-        self.assertEqual(mod.func_filename, self.file_name)
-
-    def test_incorrect_code_name(self):
-        py_compile.compile(self.file_name, dfile="another_module.py")
-        mod = self.import_module()
-        self.assertEqual(mod.module_filename, self.file_name)
-        self.assertEqual(mod.code_filename, self.file_name)
-        self.assertEqual(mod.func_filename, self.file_name)
-
-    def test_module_without_source(self):
-        target = "another_module.py"
-        py_compile.compile(self.file_name, dfile=target)
-        os.remove(self.file_name)
-        pyc_file = make_legacy_pyc(self.file_name)
-        importlib.invalidate_caches()
-        mod = self.import_module()
-        self.assertEqual(mod.module_filename, pyc_file)
-        self.assertEqual(mod.code_filename, target)
-        self.assertEqual(mod.func_filename, target)
-
-    def test_foreign_code(self):
-        py_compile.compile(self.file_name)
-        with open(self.compiled_name, "rb") as f:
-            header = f.read(12)
-            code = marshal.load(f)
-        constants = list(code.co_consts)
-        foreign_code = importlib.import_module.__code__
-        pos = constants.index(1)
-        constants[pos] = foreign_code
-        code = type(code)(code.co_argcount, code.co_kwonlyargcount,
-                          code.co_nlocals, code.co_stacksize,
-                          code.co_flags, code.co_code, tuple(constants),
-                          code.co_names, code.co_varnames, code.co_filename,
-                          code.co_name, code.co_firstlineno, code.co_lnotab,
-                          code.co_freevars, code.co_cellvars)
-        with open(self.compiled_name, "wb") as f:
-            f.write(header)
-            marshal.dump(code, f)
-        mod = self.import_module()
-        self.assertEqual(mod.constant.co_filename, foreign_code.co_filename)
-
-
-class PathsTests(unittest.TestCase):
-    SAMPLES = ('test', 'test\u00e4\u00f6\u00fc\u00df', 'test\u00e9\u00e8',
-               'test\u00b0\u00b3\u00b2')
-    path = TESTFN
-
-    def setUp(self):
-        os.mkdir(self.path)
-        self.syspath = sys.path[:]
-
-    def tearDown(self):
-        rmtree(self.path)
-        sys.path[:] = self.syspath
-
-    # Regression test for http://bugs.python.org/issue1293.
-    def test_trailing_slash(self):
-        with open(os.path.join(self.path, 'test_trailing_slash.py'), 'w') as f:
-            f.write("testdata = 'test_trailing_slash'")
-        sys.path.append(self.path+'/')
-        mod = __import__("test_trailing_slash")
-        self.assertEqual(mod.testdata, 'test_trailing_slash')
-        unload("test_trailing_slash")
-
-    # Regression test for http://bugs.python.org/issue3677.
-    @unittest.skipUnless(sys.platform == 'win32', 'Windows-specific')
-    def test_UNC_path(self):
-        with open(os.path.join(self.path, 'test_unc_path.py'), 'w') as f:
-            f.write("testdata = 'test_unc_path'")
-        importlib.invalidate_caches()
-        # Create the UNC path, like \\myhost\c$\foo\bar.
-        path = os.path.abspath(self.path)
-        import socket
-        hn = socket.gethostname()
-        drive = path[0]
-        unc = "\\\\%s\\%s$"%(hn, drive)
-        unc += path[2:]
-        try:
-            os.listdir(unc)
-        except OSError as e:
-            if e.errno in (errno.EPERM, errno.EACCES):
-                # See issue #15338
-                self.skipTest("cannot access administrative share %r" % (unc,))
-            raise
-        sys.path.insert(0, unc)
-        try:
-            mod = __import__("test_unc_path")
-        except ImportError as e:
-            self.fail("could not import 'test_unc_path' from %r: %r"
-                      % (unc, e))
-        self.assertEqual(mod.testdata, 'test_unc_path')
-        self.assertTrue(mod.__file__.startswith(unc), mod.__file__)
-        unload("test_unc_path")
-
-
-class RelativeImportTests(unittest.TestCase):
-
-    def tearDown(self):
-        unload("test.relimport")
-    setUp = tearDown
-
-    def test_relimport_star(self):
-        # This will import * from .test_import.
-        from . import relimport
-        self.assertTrue(hasattr(relimport, "RelativeImportTests"))
-
-    def test_issue3221(self):
-        # Note for mergers: the 'absolute' tests from the 2.x branch
-        # are missing in Py3k because implicit relative imports are
-        # a thing of the past
-        #
-        # Regression test for http://bugs.python.org/issue3221.
-        def check_relative():
-            exec("from . import relimport", ns)
-
-        # Check relative import OK with __package__ and __name__ correct
-        ns = dict(__package__='test', __name__='test.notarealmodule')
-        check_relative()
-
-        # Check relative import OK with only __name__ wrong
-        ns = dict(__package__='test', __name__='notarealpkg.notarealmodule')
-        check_relative()
-
-        # Check relative import fails with only __package__ wrong
-        ns = dict(__package__='foo', __name__='test.notarealmodule')
-        self.assertRaises(SystemError, check_relative)
-
-        # Check relative import fails with __package__ and __name__ wrong
-        ns = dict(__package__='foo', __name__='notarealpkg.notarealmodule')
-        self.assertRaises(SystemError, check_relative)
-
-        # Check relative import fails with package set to a non-string
-        ns = dict(__package__=object())
-        self.assertRaises(TypeError, check_relative)
-
-    def test_absolute_import_without_future(self):
-        # If explicit relative import syntax is used, then do not try
-        # to perform an absolute import in the face of failure.
-        # Issue #7902.
-        with self.assertRaises(ImportError):
-            from .os import sep
-            self.fail("explicit relative import triggered an "
-                      "implicit absolute import")
-
-
-class OverridingImportBuiltinTests(unittest.TestCase):
-    def test_override_builtin(self):
-        # Test that overriding builtins.__import__ can bypass sys.modules.
-        import os
-
-        def foo():
-            import os
-            return os
-        self.assertEqual(foo(), os)  # Quick sanity check.
-
-        with swap_attr(builtins, "__import__", lambda *x: 5):
-            self.assertEqual(foo(), 5)
-
-        # Test what happens when we shadow __import__ in globals(); this
-        # currently does not impact the import process, but if this changes,
-        # other code will need to change, so keep this test as a tripwire.
-        with swap_item(globals(), "__import__", lambda *x: 5):
-            self.assertEqual(foo(), os)
-
-
-class PycacheTests(unittest.TestCase):
-    # Test the various PEP 3147 related behaviors.
-
-    tag = sys.implementation.cache_tag
-
-    def _clean(self):
-        forget(TESTFN)
-        rmtree('__pycache__')
-        unlink(self.source)
-
-    def setUp(self):
-        self.source = TESTFN + '.py'
-        self._clean()
-        with open(self.source, 'w') as fp:
-            print('# This is a test file written by test_import.py', file=fp)
-        sys.path.insert(0, os.curdir)
-        importlib.invalidate_caches()
-
-    def tearDown(self):
-        assert sys.path[0] == os.curdir, 'Unexpected sys.path[0]'
-        del sys.path[0]
-        self._clean()
-
-    @skip_if_dont_write_bytecode
-    def test_import_pyc_path(self):
-        self.assertFalse(os.path.exists('__pycache__'))
-        __import__(TESTFN)
-        self.assertTrue(os.path.exists('__pycache__'))
-        self.assertTrue(os.path.exists(os.path.join(
-            '__pycache__', '{}.{}.py{}'.format(
-            TESTFN, self.tag, 'c' if __debug__ else 'o'))))
-
-    @unittest.skipUnless(os.name == 'posix',
-                         "test meaningful only on posix systems")
-    @unittest.skipIf(hasattr(os, 'geteuid') and os.geteuid() == 0,
-            "due to varying filesystem permission semantics (issue #11956)")
-    @skip_if_dont_write_bytecode
-    def test_unwritable_directory(self):
-        # When the umask causes the new __pycache__ directory to be
-        # unwritable, the import still succeeds but no .pyc file is written.
-        with temp_umask(0o222):
-            __import__(TESTFN)
-        self.assertTrue(os.path.exists('__pycache__'))
-        self.assertFalse(os.path.exists(os.path.join(
-            '__pycache__', '{}.{}.pyc'.format(TESTFN, self.tag))))
-
-    @skip_if_dont_write_bytecode
-    def test_missing_source(self):
-        # With PEP 3147 cache layout, removing the source but leaving the pyc
-        # file does not satisfy the import.
-        __import__(TESTFN)
-        pyc_file = importlib.util.cache_from_source(self.source)
-        self.assertTrue(os.path.exists(pyc_file))
-        os.remove(self.source)
-        forget(TESTFN)
-        importlib.invalidate_caches()
-        self.assertRaises(ImportError, __import__, TESTFN)
-
-    @skip_if_dont_write_bytecode
-    def test_missing_source_legacy(self):
-        # Like test_missing_source() except that for backward compatibility,
-        # when the pyc file lives where the py file would have been (and named
-        # without the tag), it is importable.  The __file__ of the imported
-        # module is the pyc location.
-        __import__(TESTFN)
-        # pyc_file gets removed in _clean() via tearDown().
-        pyc_file = make_legacy_pyc(self.source)
-        os.remove(self.source)
-        unload(TESTFN)
-        importlib.invalidate_caches()
-        m = __import__(TESTFN)
-        self.assertEqual(m.__file__,
-                         os.path.join(os.curdir, os.path.relpath(pyc_file)))
-
-    def test___cached__(self):
-        # Modules now also have an __cached__ that points to the pyc file.
-        m = __import__(TESTFN)
-        pyc_file = importlib.util.cache_from_source(TESTFN + '.py')
-        self.assertEqual(m.__cached__, os.path.join(os.curdir, pyc_file))
-
-    @skip_if_dont_write_bytecode
-    def test___cached___legacy_pyc(self):
-        # Like test___cached__() except that for backward compatibility,
-        # when the pyc file lives where the py file would have been (and named
-        # without the tag), it is importable.  The __cached__ of the imported
-        # module is the pyc location.
-        __import__(TESTFN)
-        # pyc_file gets removed in _clean() via tearDown().
-        pyc_file = make_legacy_pyc(self.source)
-        os.remove(self.source)
-        unload(TESTFN)
-        importlib.invalidate_caches()
-        m = __import__(TESTFN)
-        self.assertEqual(m.__cached__,
-                         os.path.join(os.curdir, os.path.relpath(pyc_file)))
-
-    @skip_if_dont_write_bytecode
-    def test_package___cached__(self):
-        # Like test___cached__ but for packages.
-        def cleanup():
-            rmtree('pep3147')
-            unload('pep3147.foo')
-            unload('pep3147')
-        os.mkdir('pep3147')
-        self.addCleanup(cleanup)
-        # Touch the __init__.py
-        with open(os.path.join('pep3147', '__init__.py'), 'w'):
-            pass
-        with open(os.path.join('pep3147', 'foo.py'), 'w'):
-            pass
-        importlib.invalidate_caches()
-        m = __import__('pep3147.foo')
-        init_pyc = importlib.util.cache_from_source(
-            os.path.join('pep3147', '__init__.py'))
-        self.assertEqual(m.__cached__, os.path.join(os.curdir, init_pyc))
-        foo_pyc = importlib.util.cache_from_source(os.path.join('pep3147', 'foo.py'))
-        self.assertEqual(sys.modules['pep3147.foo'].__cached__,
-                         os.path.join(os.curdir, foo_pyc))
-
-    def test_package___cached___from_pyc(self):
-        # Like test___cached__ but ensuring __cached__ when imported from a
-        # PEP 3147 pyc file.
-        def cleanup():
-            rmtree('pep3147')
-            unload('pep3147.foo')
-            unload('pep3147')
-        os.mkdir('pep3147')
-        self.addCleanup(cleanup)
-        # Touch the __init__.py
-        with open(os.path.join('pep3147', '__init__.py'), 'w'):
-            pass
-        with open(os.path.join('pep3147', 'foo.py'), 'w'):
-            pass
-        importlib.invalidate_caches()
-        m = __import__('pep3147.foo')
-        unload('pep3147.foo')
-        unload('pep3147')
-        importlib.invalidate_caches()
-        m = __import__('pep3147.foo')
-        init_pyc = importlib.util.cache_from_source(
-            os.path.join('pep3147', '__init__.py'))
-        self.assertEqual(m.__cached__, os.path.join(os.curdir, init_pyc))
-        foo_pyc = importlib.util.cache_from_source(os.path.join('pep3147', 'foo.py'))
-        self.assertEqual(sys.modules['pep3147.foo'].__cached__,
-                         os.path.join(os.curdir, foo_pyc))
-
-    def test_recompute_pyc_same_second(self):
-        # Even when the source file doesn't change timestamp, a change in
-        # source size is enough to trigger recomputation of the pyc file.
-        __import__(TESTFN)
-        unload(TESTFN)
-        with open(self.source, 'a') as fp:
-            print("x = 5", file=fp)
-        m = __import__(TESTFN)
-        self.assertEqual(m.x, 5)
-
-
-class TestSymbolicallyLinkedPackage(unittest.TestCase):
-    package_name = 'sample'
-    tagged = package_name + '-tagged'
-
-    def setUp(self):
-        test.support.rmtree(self.tagged)
-        test.support.rmtree(self.package_name)
-        self.orig_sys_path = sys.path[:]
-
-        # create a sample package; imagine you have a package with a tag and
-        #  you want to symbolically link it from its untagged name.
-        os.mkdir(self.tagged)
-        self.addCleanup(test.support.rmtree, self.tagged)
-        init_file = os.path.join(self.tagged, '__init__.py')
-        test.support.create_empty_file(init_file)
-        assert os.path.exists(init_file)
-
-        # now create a symlink to the tagged package
-        # sample -> sample-tagged
-        os.symlink(self.tagged, self.package_name, target_is_directory=True)
-        self.addCleanup(test.support.unlink, self.package_name)
-        importlib.invalidate_caches()
-
-        self.assertEqual(os.path.isdir(self.package_name), True)
-
-        assert os.path.isfile(os.path.join(self.package_name, '__init__.py'))
-
-    def tearDown(self):
-        sys.path[:] = self.orig_sys_path
-
-    # regression test for issue6727
-    @unittest.skipUnless(
-        not hasattr(sys, 'getwindowsversion')
-        or sys.getwindowsversion() >= (6, 0),
-        "Windows Vista or later required")
-    @test.support.skip_unless_symlink
-    def test_symlinked_dir_importable(self):
-        # make sure sample can only be imported from the current directory.
-        sys.path[:] = ['.']
-        assert os.path.exists(self.package_name)
-        assert os.path.exists(os.path.join(self.package_name, '__init__.py'))
-
-        # Try to import the package
-        importlib.import_module(self.package_name)
-
-
-@cpython_only
-class ImportlibBootstrapTests(unittest.TestCase):
-    # These tests check that importlib is bootstrapped.
-
-    def test_frozen_importlib(self):
-        mod = sys.modules['_frozen_importlib']
-        self.assertTrue(mod)
-
-    def test_frozen_importlib_is_bootstrap(self):
-        from importlib import _bootstrap
-        mod = sys.modules['_frozen_importlib']
-        self.assertIs(mod, _bootstrap)
-        self.assertEqual(mod.__name__, 'importlib._bootstrap')
-        self.assertEqual(mod.__package__, 'importlib')
-        self.assertTrue(mod.__file__.endswith('_bootstrap.py'), mod.__file__)
-
-    def test_there_can_be_only_one(self):
-        # Issue #15386 revealed a tricky loophole in the bootstrapping
-        # This test is technically redundant, since the bug caused importing
-        # this test module to crash completely, but it helps prove the point
-        from importlib import machinery
-        mod = sys.modules['_frozen_importlib']
-        self.assertIs(machinery.FileFinder, mod.FileFinder)
-
-
-@cpython_only
-class GetSourcefileTests(unittest.TestCase):
-
-    """Test importlib._bootstrap._get_sourcefile() as used by the C API.
-
-    Because of the peculiarities of the need of this function, the tests are
-    knowingly whitebox tests.
-
-    """
-
-    def test_get_sourcefile(self):
-        # Given a valid bytecode path, return the path to the corresponding
-        # source file if it exists.
-        with mock.patch('importlib._bootstrap._path_isfile') as _path_isfile:
-            _path_isfile.return_value = True;
-            path = TESTFN + '.pyc'
-            expect = TESTFN + '.py'
-            self.assertEqual(_get_sourcefile(path), expect)
-
-    def test_get_sourcefile_no_source(self):
-        # Given a valid bytecode path without a corresponding source path,
-        # return the original bytecode path.
-        with mock.patch('importlib._bootstrap._path_isfile') as _path_isfile:
-            _path_isfile.return_value = False;
-            path = TESTFN + '.pyc'
-            self.assertEqual(_get_sourcefile(path), path)
-
-    def test_get_sourcefile_bad_ext(self):
-        # Given a path with an invalid bytecode extension, return the
-        # bytecode path passed as the argument.
-        path = TESTFN + '.bad_ext'
-        self.assertEqual(_get_sourcefile(path), path)
-
-
-class ImportTracebackTests(unittest.TestCase):
-
-    def setUp(self):
-        os.mkdir(TESTFN)
-        self.old_path = sys.path[:]
-        sys.path.insert(0, TESTFN)
-
-    def tearDown(self):
-        sys.path[:] = self.old_path
-        rmtree(TESTFN)
-
-    def create_module(self, mod, contents, ext=".py"):
-        fname = os.path.join(TESTFN, mod + ext)
-        with open(fname, "w") as f:
-            f.write(contents)
-        self.addCleanup(unload, mod)
-        importlib.invalidate_caches()
-        return fname
-
-    def assert_traceback(self, tb, files):
-        deduped_files = []
-        while tb:
-            code = tb.tb_frame.f_code
-            fn = code.co_filename
-            if not deduped_files or fn != deduped_files[-1]:
-                deduped_files.append(fn)
-            tb = tb.tb_next
-        self.assertEqual(len(deduped_files), len(files), deduped_files)
-        for fn, pat in zip(deduped_files, files):
-            self.assertIn(pat, fn)
-
-    def test_nonexistent_module(self):
-        try:
-            # assertRaises() clears __traceback__
-            import nonexistent_xyzzy
-        except ImportError as e:
-            tb = e.__traceback__
-        else:
-            self.fail("ImportError should have been raised")
-        self.assert_traceback(tb, [__file__])
-
-    def test_nonexistent_module_nested(self):
-        self.create_module("foo", "import nonexistent_xyzzy")
-        try:
-            import foo
-        except ImportError as e:
-            tb = e.__traceback__
-        else:
-            self.fail("ImportError should have been raised")
-        self.assert_traceback(tb, [__file__, 'foo.py'])
-
-    def test_exec_failure(self):
-        self.create_module("foo", "1/0")
-        try:
-            import foo
-        except ZeroDivisionError as e:
-            tb = e.__traceback__
-        else:
-            self.fail("ZeroDivisionError should have been raised")
-        self.assert_traceback(tb, [__file__, 'foo.py'])
-
-    def test_exec_failure_nested(self):
-        self.create_module("foo", "import bar")
-        self.create_module("bar", "1/0")
-        try:
-            import foo
-        except ZeroDivisionError as e:
-            tb = e.__traceback__
-        else:
-            self.fail("ZeroDivisionError should have been raised")
-        self.assert_traceback(tb, [__file__, 'foo.py', 'bar.py'])
-
-    # A few more examples from issue #15425
-    def test_syntax_error(self):
-        self.create_module("foo", "invalid syntax is invalid")
-        try:
-            import foo
-        except SyntaxError as e:
-            tb = e.__traceback__
-        else:
-            self.fail("SyntaxError should have been raised")
-        self.assert_traceback(tb, [__file__])
-
-    def _setup_broken_package(self, parent, child):
-        pkg_name = "_parent_foo"
-        self.addCleanup(unload, pkg_name)
-        pkg_path = os.path.join(TESTFN, pkg_name)
-        os.mkdir(pkg_path)
-        # Touch the __init__.py
-        init_path = os.path.join(pkg_path, '__init__.py')
-        with open(init_path, 'w') as f:
-            f.write(parent)
-        bar_path = os.path.join(pkg_path, 'bar.py')
-        with open(bar_path, 'w') as f:
-            f.write(child)
-        importlib.invalidate_caches()
-        return init_path, bar_path
-
-    def test_broken_submodule(self):
-        init_path, bar_path = self._setup_broken_package("", "1/0")
-        try:
-            import _parent_foo.bar
-        except ZeroDivisionError as e:
-            tb = e.__traceback__
-        else:
-            self.fail("ZeroDivisionError should have been raised")
-        self.assert_traceback(tb, [__file__, bar_path])
-
-    def test_broken_from(self):
-        init_path, bar_path = self._setup_broken_package("", "1/0")
-        try:
-            from _parent_foo import bar
-        except ZeroDivisionError as e:
-            tb = e.__traceback__
-        else:
-            self.fail("ImportError should have been raised")
-        self.assert_traceback(tb, [__file__, bar_path])
-
-    def test_broken_parent(self):
-        init_path, bar_path = self._setup_broken_package("1/0", "")
-        try:
-            import _parent_foo.bar
-        except ZeroDivisionError as e:
-            tb = e.__traceback__
-        else:
-            self.fail("ZeroDivisionError should have been raised")
-        self.assert_traceback(tb, [__file__, init_path])
-
-    def test_broken_parent_from(self):
-        init_path, bar_path = self._setup_broken_package("1/0", "")
-        try:
-            from _parent_foo import bar
-        except ZeroDivisionError as e:
-            tb = e.__traceback__
-        else:
-            self.fail("ZeroDivisionError should have been raised")
-        self.assert_traceback(tb, [__file__, init_path])
-
-    @cpython_only
-    def test_import_bug(self):
-        # We simulate a bug in importlib and check that it's not stripped
-        # away from the traceback.
-        self.create_module("foo", "")
-        importlib = sys.modules['_frozen_importlib']
-        if 'load_module' in vars(importlib.SourceLoader):
-            old_exec_module = importlib.SourceLoader.exec_module
-        else:
-            old_exec_module = None
-        try:
-            def exec_module(*args):
-                1/0
-            importlib.SourceLoader.exec_module = exec_module
-            try:
-                import foo
-            except ZeroDivisionError as e:
-                tb = e.__traceback__
-            else:
-                self.fail("ZeroDivisionError should have been raised")
-            self.assert_traceback(tb, [__file__, '<frozen importlib', __file__])
-        finally:
-            if old_exec_module is None:
-                del importlib.SourceLoader.exec_module
-            else:
-                importlib.SourceLoader.exec_module = old_exec_module
-
-    @unittest.skipUnless(TESTFN_UNENCODABLE, 'need TESTFN_UNENCODABLE')
-    def test_unencodable_filename(self):
-        # Issue #11619: The Python parser and the import machinery must not
-        # encode filenames, especially on Windows
-        pyname = script_helper.make_script('', TESTFN_UNENCODABLE, 'pass')
-        self.addCleanup(unlink, pyname)
-        name = pyname[:-3]
-        script_helper.assert_python_ok("-c", "mod = __import__(%a)" % name,
-                                       __isolated=False)
-
-
-if __name__ == '__main__':
-    # Test needs to be a package, so we can do relative imports.
-    unittest.main()