shutil.move() moves directory contents if target dir exists

[FelixSchwarz]

I noticed that shutil.move() behaves differently if the target directory exists already.

Python:

• if the target directory exists, move the source directory as a sub-directory of the target dir
• if target directory does not exist, create it and move only contents of source directory

pyfakefs:

• always moves contents of source directory only.

I noticed this with Python 2.7 (pyfakefs 3.7.1) and Python 3.8 (latest git, 025f06c).

Related bug was #145 (fixed by e94bb0f) but it seems that one missed this edge condition.

Example code:

#!/usr/bin/env python

import os
import shutil
import tempfile

USE_PYFAKEFS = False

if USE_PYFAKEFS:
    from pyfakefs.fake_filesystem_unittest import Patcher
    stubber = Patcher()
    stubber.setUp()


source_dir = tempfile.mkdtemp()
target_dir = tempfile.mkdtemp()
filename = 'foo.pdf'
with open(os.path.join(source_dir, filename), 'wb') as fp:
    fp.write(b'stub')

shutil.move(source_dir, target_dir)
shutil.rmtree(target_dir)

[mrbean-bremen]

Thanks! I will try to have a look later tonight.

[mrbean-bremen]

Ok, as we do not patch shutil functionality, but rely on the native implementation (this has been changed after #145 had been fixed), the real problem seems to be the fake implementation of os.rename - this is used by shutil and seems to handle this case incorrectly. I will have a go at this somewhere in the next days.

[mrbean-bremen]

Ok, turned out to be yet another problem.

The root cause was that no st_ino had been set for the created directory in fake mkdir. That let to os.samefile not work correctly, as it uses st_ino for comparison, e.g. two different newly created directories are seen as the same object. As os.samefile is used by shutil.move internally, it handled the move as a simple rename.

Thanks for catching this bug!

[FelixSchwarz]

Thank you :-)