mocking os.path.isdir

directory_structure.txt

.
├── bar
├── foo
├── scripts
│   ├── foobar.py
│   └── __init__.py
└── tests
    ├── foobar_test.py
    └── __init__.py

run_command.sh

#!/bin/bash

python -m unittest discover -s tests/ -p '*_test.py'

scripts__foobar.py

import os

def get_dirname(filename):
  return os.path.dirname(filename)

def get_parent_dirname(filename):
  return os.path.abspath(os.path.join(filename, os.pardir))

def get_dir_contents(filename):
  return os.listdir(filename)

def fullpaths(dirname, names):
  return [os.path.join(dirname, name) for name in names]

def just_files(folder_contents):
  is_a_file = lambda f: os.path.isfile(f) and not os.path.islink(f)
  return filter(is_a_file, folder_contents)

def just_dirs(folder_contents):
  return filter(os.path.isdir, folder_contents)

def just_links(folder_contents):
  return filter(os.path.islink, folder_contents)

if __name__ == '__main__':
  my_directory = get_dirname(__file__)
  my_parent = get_parent_dirname(my_directory)
  my_siblings = get_dir_contents(my_parent)
  full_my_siblings = fullpaths(my_parent, my_siblings)
  my_sibling_files = just_files(full_my_siblings)
  print my_sibling_files

tests__foobar_test.py

import unittest
import mock
from scripts import foobar

class TestFooBar(unittest.TestCase):

  def is_a_file(self, filename):
    return 'file' in filename or self.is_a_link(filename)

  def is_a_dir(self, filename):
    return 'dir' in filename

  def is_a_link(self, filename):
    return 'link' in filename

  @mock.patch('scripts.foobar.os')
  def test_just_files(self, os_mock):
    os_mock.path.isfile.side_effect = self.is_a_file
    os_mock.path.islink.side_effect = self.is_a_link
    os_mock.path.isdir.side_effect = self.is_a_dir
    files = foobar.just_files(['file_foo', 'dir_bar', 'link_baz'])
    self.assertEqual(files, ['file_foo'])

  @mock.patch('scripts.foobar.os')
  def test_just_dirs(self, os_mock):
    os_mock.path.isfile.side_effect = self.is_a_file
    os_mock.path.islink.side_effect = self.is_a_link
    os_mock.path.isdir.side_effect = self.is_a_dir
    files = foobar.just_dirs(['file_foo', 'dir_bar', 'link_baz'])
    self.assertEqual(files, ['dir_bar'])

  @mock.patch('scripts.foobar.os')
  def test_just_links(self, os_mock):
    os_mock.path.isfile.side_effect = self.is_a_file
    os_mock.path.islink.side_effect = self.is_a_link
    os_mock.path.isdir.side_effect = self.is_a_dir
    files = foobar.just_links(['file_foo', 'dir_bar', 'link_baz'])
    self.assertEqual(files, ['link_baz'])