test_import.py 文件源码

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')