``` import shutil import pyfakefs.fake_filesystem import os ROOT_PATH = "/Volumes/ramdisk/test" fs = pyfakefs.fake_filesystem.FakeFilesystem() fs.CreateDirectory('/Volumes') fs.CreateDirectory('/Volumes/ramdisk') fs.CreateDirectory('/Volumes/ramdisk/test') os0 = pyfakefs.fake_filesystem.FakeOsModule(fs) opener0 = pyfakefs.fake_filesystem.FakeFileOpen(fs) if False: os0 = os shutil.rmtree(ROOT_PATH) os.mkdir(ROOT_PATH) opener0 = open path0 = ROOT_PATH path1 = ROOT_PATH component0 = "alpha" path0 += os.path.sep + component0 file0 = opener0(path0,'w') path1 += os.path.sep + component0 component0 = "" path0 += os.path.sep + component0 os0.rename(path0,path1) ``` OS raises `OSError: [Errno 20] Not a directory`