path: root/pyfakefs/tests/fake_filesystem_test.py

# Copyright 2009 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Unittest for fake_filesystem module."""

import contextlib
import errno
import os
import stat
import sys
import unittest
from unittest.mock import patch

from pyfakefs import fake_filesystem, fake_os, fake_open
from pyfakefs.fake_filesystem import (
    set_uid,
    set_gid,
    is_root,
    reset_ids,
    OSType,
)
from pyfakefs.helpers import IS_WIN
from pyfakefs.tests.test_utils import TestCase, RealFsTestCase, time_mock


class FakeDirectoryUnitTest(TestCase):
    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(path_separator="/")
        self.os = fake_os.FakeOsModule(self.filesystem)
        self.time = time_mock(10, 1)
        self.time.start()
        self.fake_file = fake_filesystem.FakeFile(
            "foobar", contents="dummy_file", filesystem=self.filesystem
        )
        self.fake_dir = fake_filesystem.FakeDirectory(
            "somedir", filesystem=self.filesystem
        )

    def tearDown(self):
        self.time.stop()

    def test_new_file_and_directory(self):
        self.assertTrue(stat.S_IFREG & self.fake_file.st_mode)
        self.assertTrue(stat.S_IFDIR & self.fake_dir.st_mode)
        self.assertEqual({}, self.fake_dir.entries)

    def test_add_entry(self):
        self.fake_dir.add_entry(self.fake_file)
        self.assertEqual({"foobar": self.fake_file}, self.fake_dir.entries)

    def test_get_entry(self):
        self.fake_dir.add_entry(self.fake_file)
        self.assertEqual(self.fake_file, self.fake_dir.get_entry("foobar"))

    def test_path(self):
        root_dir = self.filesystem.root_dir_name
        self.filesystem.root.add_entry(self.fake_dir)
        self.fake_dir.add_entry(self.fake_file)
        self.assertEqual(f"{root_dir}somedir/foobar", self.fake_file.path)
        self.assertEqual(f"{root_dir}somedir", self.fake_dir.path)

    def test_path_with_drive(self):
        self.filesystem.is_windows_fs = True
        dir_path = "C:/foo/bar/baz"
        self.filesystem.create_dir(dir_path)
        dir_object = self.filesystem.get_object(dir_path)
        self.assertEqual(dir_path, dir_object.path)

    def test_path_after_chdir(self):
        root_dir = self.filesystem.root_dir_name
        dir_path = "/foo/bar/baz"
        self.filesystem.create_dir(dir_path)
        self.os.chdir(dir_path)
        dir_object = self.filesystem.get_object(dir_path)
        self.assertEqual(f"{root_dir}foo/bar/baz", dir_object.path)

    def test_path_after_chdir_with_drive(self):
        self.filesystem.is_windows_fs = True
        dir_path = "C:/foo/bar/baz"
        self.filesystem.create_dir(dir_path)
        self.os.chdir(dir_path)
        dir_object = self.filesystem.get_object(dir_path)
        self.assertEqual(dir_path, dir_object.path)

    def test_remove_entry(self):
        self.fake_dir.add_entry(self.fake_file)
        self.assertEqual(self.fake_file, self.fake_dir.get_entry("foobar"))
        self.fake_dir.remove_entry("foobar")
        with self.assertRaises(KeyError):
            self.fake_dir.get_entry("foobar")

    def test_should_throw_if_set_size_is_not_integer(self):
        with self.raises_os_error(errno.ENOSPC):
            self.fake_file.size = 0.1

    def test_should_throw_if_set_size_is_negative(self):
        with self.raises_os_error(errno.ENOSPC):
            self.fake_file.size = -1

    def test_produce_empty_file_if_set_size_is_zero(self):
        self.fake_file.size = 0
        self.assertEqual("", self.fake_file.contents)

    def test_sets_content_empty_if_set_size_is_zero(self):
        self.fake_file.size = 0
        self.assertEqual("", self.fake_file.contents)

    def test_truncate_file_if_size_is_smaller_than_current_size(self):
        self.fake_file.size = 6
        self.assertEqual("dummy_", self.fake_file.contents)

    def test_leave_file_unchanged_if_size_is_equal_to_current_size(self):
        self.fake_file.size = 10
        self.assertEqual("dummy_file", self.fake_file.contents)

    def test_set_contents_to_dir_raises(self):
        # Regression test for #276
        self.filesystem.is_windows_fs = True
        with self.raises_os_error(errno.EISDIR):
            self.fake_dir.set_contents("a")
        self.filesystem.is_windows_fs = False
        with self.raises_os_error(errno.EISDIR):
            self.fake_dir.set_contents("a")

    def test_pads_with_nullbytes_if_size_is_greater_than_current_size(self):
        self.fake_file.size = 13
        self.assertEqual("dummy_file\0\0\0", self.fake_file.contents)

    def test_set_m_time(self):
        self.assertEqual(10, self.fake_file.st_mtime)
        self.fake_file.st_mtime = 14
        self.assertEqual(14, self.fake_file.st_mtime)
        self.fake_file.st_mtime = 131
        self.assertEqual(131, self.fake_file.st_mtime)

    def test_file_inode(self):
        filesystem = fake_filesystem.FakeFilesystem(path_separator="/")
        fake_os_module = fake_os.FakeOsModule(filesystem)
        file_path = "some_file1"
        filesystem.create_file(file_path, contents="contents here1")
        self.assertLess(0, fake_os_module.stat(file_path)[stat.ST_INO])

        file_obj = filesystem.get_object(file_path)
        file_obj.st_ino = 43
        self.assertEqual(43, fake_os_module.stat(file_path)[stat.ST_INO])

    def test_directory_inode(self):
        filesystem = fake_filesystem.FakeFilesystem(path_separator="/")
        fake_os_module = fake_os.FakeOsModule(filesystem)
        dirpath = "testdir"
        filesystem.create_dir(dirpath)
        self.assertLess(0, fake_os_module.stat(dirpath)[stat.ST_INO])

        dir_obj = filesystem.get_object(dirpath)
        dir_obj.st_ino = 43
        self.assertEqual(43, fake_os_module.stat(dirpath)[stat.ST_INO])

    def test_directory_size(self):
        fs = fake_filesystem.FakeFilesystem(path_separator="/")
        foo_dir = fs.create_dir("/foo")
        fs.create_file("/foo/bar.txt", st_size=20)
        bar_dir = fs.create_dir("/foo/bar/")
        fs.create_file("/foo/bar/baz1.txt", st_size=30)
        fs.create_file("/foo/bar/baz2.txt", st_size=40)
        foo1_dir = fs.create_dir("/foo1")
        fs.create_file("/foo1/bar.txt", st_size=50)
        fs.create_file("/foo1/bar/baz/file", st_size=60)
        self.assertEqual(90, foo_dir.size)
        self.assertEqual(70, bar_dir.size)
        self.assertEqual(110, foo1_dir.size)
        self.assertEqual(200, fs.root_dir.size)
        with self.raises_os_error(errno.EISDIR):
            foo1_dir.size = 100

    def test_ordered_dirs(self):
        filesystem = fake_filesystem.FakeFilesystem(path_separator="/")
        filesystem.create_dir("/foo")
        filesystem.create_file("/foo/2")
        filesystem.create_file("/foo/4")
        filesystem.create_file("/foo/1")
        filesystem.create_file("/foo/3")
        fake_dir = filesystem.get_object("/foo")
        self.assertEqual(["2", "4", "1", "3"], fake_dir.ordered_dirs)


class SetLargeFileSizeTest(TestCase):
    def setUp(self):
        filesystem = fake_filesystem.FakeFilesystem()
        self.fake_file = fake_filesystem.FakeFile("foobar", filesystem=filesystem)

    def test_should_throw_if_size_is_not_integer(self):
        with self.raises_os_error(errno.ENOSPC):
            self.fake_file.set_large_file_size(0.1)

    def test_should_throw_if_size_is_negative(self):
        with self.raises_os_error(errno.ENOSPC):
            self.fake_file.set_large_file_size(-1)

    def test_sets_content_none_if_size_is_non_negative_integer(self):
        self.fake_file.set_large_file_size(1000000000)
        self.assertEqual(None, self.fake_file.contents)
        self.assertEqual(1000000000, self.fake_file.st_size)


class NormalizePathTest(TestCase):
    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(path_separator="/")
        self.root_name = self.filesystem.root_dir_name

    def test_empty_path_should_get_normalized_to_root_path(self):
        self.assertEqual(self.root_name, self.filesystem.absnormpath(""))

    def test_root_path_remains_unchanged(self):
        self.assertEqual(self.root_name, self.filesystem.absnormpath(self.root_name))

    def test_relative_path_forced_to_cwd(self):
        path = "bar"
        self.filesystem.cwd = "/foo"
        self.assertEqual("/foo/bar", self.filesystem.absnormpath(path))

    def test_absolute_path_remains_unchanged(self):
        path = "foo/bar"
        self.assertEqual(self.root_name + path, self.filesystem.absnormpath(path))

    def test_dotted_path_is_normalized(self):
        path = "/foo/.."
        self.assertEqual(
            self.filesystem.root_dir_name, self.filesystem.absnormpath(path)
        )
        path = "foo/../bar"
        self.assertEqual(
            f"{self.filesystem.root_dir_name}bar",
            self.filesystem.absnormpath(path),
        )

    def test_dot_path_is_normalized(self):
        path = "."
        self.assertEqual(self.root_name, self.filesystem.absnormpath(path))


class GetPathComponentsTest(TestCase):
    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(path_separator="/")
        self.root_name = "/"

    def test_root_path_should_return_empty_list(self):
        self.assertEqual([], self.filesystem._path_components(self.root_name))

    def test_empty_path_should_return_empty_list(self):
        self.assertEqual([], self.filesystem._path_components(""))

    def test_relative_path_with_one_component_should_return_component(self):
        self.assertEqual(["foo"], self.filesystem._path_components("foo"))

    def test_absolute_path_with_one_component_should_return_component(self):
        self.assertEqual(["foo"], self.filesystem._path_components("/foo"))

    def test_two_level_relative_path_should_return_components(self):
        self.assertEqual(["foo", "bar"], self.filesystem._path_components("foo/bar"))

    def test_two_level_absolute_path_should_return_components(self):
        self.assertEqual(["foo", "bar"], self.filesystem._path_components("/foo/bar"))


class FakeFilesystemUnitTest(TestCase):
    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(path_separator="/")
        self.root_name = self.filesystem.root_dir_name
        self.fake_file = fake_filesystem.FakeFile("foobar", filesystem=self.filesystem)
        self.fake_child = fake_filesystem.FakeDirectory(
            "foobaz", filesystem=self.filesystem
        )
        self.fake_grandchild = fake_filesystem.FakeDirectory(
            "quux", filesystem=self.filesystem
        )

    def test_new_filesystem(self):
        self.assertEqual("/", self.filesystem.path_separator)
        self.assertTrue(stat.S_IFDIR & self.filesystem.root.st_mode)
        self.assertEqual({}, self.filesystem.root_dir.entries)

    def test_none_raises_type_error(self):
        with self.assertRaises(TypeError):
            self.filesystem.exists(None)

    def test_empty_string_does_not_exist(self):
        self.assertFalse(self.filesystem.exists(""))

    def test_exists_root(self):
        self.assertTrue(self.filesystem.exists(self.root_name))

    def test_exists_unadded_file(self):
        self.assertFalse(self.filesystem.exists(self.fake_file.name))

    def test_not_exists_subpath_named_like_file_contents(self):
        # Regression test for #219
        file_path = "/foo/bar"
        self.filesystem.create_file(file_path, contents="baz")
        self.assertFalse(self.filesystem.exists(file_path + "/baz"))

    def test_get_root_object(self):
        self.assertEqual(
            self.filesystem.root_dir,
            self.filesystem.get_object(self.root_name),
        )

    def test_add_object_to_root(self):
        self.filesystem.add_object(self.root_name, self.fake_file)
        self.assertEqual({"foobar": self.fake_file}, self.filesystem.root_dir.entries)

    def test_windows_root_dir_name(self):
        self.filesystem.is_windows_fs = True
        self.assertEqual("C:/", self.filesystem.root_dir_name)
        self.filesystem.cwd = "E:/foo"
        self.assertEqual("E:/", self.filesystem.root_dir_name)
        self.filesystem.cwd = "//foo/bar"
        self.assertEqual("//foo/bar/", self.filesystem.root_dir_name)

    def test_exists_added_file(self):
        self.filesystem.add_object(self.root_name, self.fake_file)
        self.assertTrue(self.filesystem.exists(self.fake_file.name))

    def test_exists_relative_path_posix(self):
        self.filesystem.is_windows_fs = False
        self.filesystem.create_file("/a/b/file_one")
        self.filesystem.create_file("/a/c/file_two")
        self.assertTrue(self.filesystem.exists("a/b/../c/file_two"))
        self.assertTrue(self.filesystem.exists("/a/c/../b/file_one"))
        self.assertTrue(self.filesystem.exists("/a/c/../../a/b/file_one"))
        self.assertFalse(self.filesystem.exists("a/b/../z/d"))
        self.assertFalse(self.filesystem.exists("a/b/../z/../c/file_two"))
        self.filesystem.cwd = "/a/c"
        self.assertTrue(self.filesystem.exists("../b/file_one"))
        self.assertTrue(self.filesystem.exists("../../a/b/file_one"))
        self.assertTrue(self.filesystem.exists("../../a/b/../../a/c/file_two"))
        self.assertFalse(self.filesystem.exists("../z/file_one"))
        self.assertFalse(self.filesystem.exists("../z/../c/file_two"))

    def test_exists_relative_path_windows(self):
        self.filesystem.is_windows_fs = True
        self.filesystem.is_macos = False
        self.filesystem.create_file("/a/b/file_one")
        self.filesystem.create_file("/a/c/file_two")
        self.assertTrue(self.filesystem.exists("a/b/../c/file_two"))
        self.assertTrue(self.filesystem.exists("/a/c/../b/file_one"))
        self.assertTrue(self.filesystem.exists("/a/c/../../a/b/file_one"))
        self.assertFalse(self.filesystem.exists("a/b/../z/d"))
        self.assertTrue(self.filesystem.exists("a/b/../z/../c/file_two"))
        self.filesystem.cwd = "C:/a/c"
        self.assertTrue(self.filesystem.exists("../b/file_one"))
        self.assertTrue(self.filesystem.exists("../../a/b/file_one"))
        self.assertTrue(self.filesystem.exists("../../a/b/../../a/c/file_two"))
        self.assertFalse(self.filesystem.exists("../z/file_one"))
        self.assertTrue(self.filesystem.exists("../z/../c/file_two"))

    def test_get_object_from_root(self):
        self.filesystem.add_object(self.root_name, self.fake_file)
        self.assertEqual(self.fake_file, self.filesystem.get_object("foobar"))

    def test_get_nonexistent_object_from_root_error(self):
        self.filesystem.add_object(self.root_name, self.fake_file)
        self.assertEqual(self.fake_file, self.filesystem.get_object("foobar"))
        with self.raises_os_error(errno.ENOENT):
            self.filesystem.get_object("some_bogus_filename")

    def test_remove_object_from_root(self):
        self.filesystem.add_object(self.root_name, self.fake_file)
        self.filesystem.remove_object(self.fake_file.name)
        with self.raises_os_error(errno.ENOENT):
            self.filesystem.get_object(self.fake_file.name)

    def test_remove_nonexisten_object_from_root_error(self):
        with self.raises_os_error(errno.ENOENT):
            self.filesystem.remove_object("some_bogus_filename")

    def test_exists_removed_file(self):
        self.filesystem.add_object(self.root_name, self.fake_file)
        self.filesystem.remove_object(self.fake_file.name)
        self.assertFalse(self.filesystem.exists(self.fake_file.name))

    def test_add_object_to_child(self):
        self.filesystem.add_object(self.root_name, self.fake_child)
        self.filesystem.add_object(self.fake_child.name, self.fake_file)
        self.assertEqual(
            {self.fake_file.name: self.fake_file},
            self.filesystem.root_dir.get_entry(self.fake_child.name).entries,
        )

    def test_add_object_to_regular_file_error_posix(self):
        self.filesystem.is_windows_fs = False
        self.filesystem.add_object(self.filesystem.root_dir_name, self.fake_file)
        with self.raises_os_error(errno.ENOTDIR):
            self.filesystem.add_object(self.fake_file.name, self.fake_file)

    def test_add_object_to_regular_file_error_windows(self):
        self.filesystem.is_windows_fs = True
        self.filesystem.add_object(self.root_name, self.fake_file)
        with self.raises_os_error(errno.ENOENT):
            self.filesystem.add_object(self.fake_file.name, self.fake_file)

    def test_exists_file_added_to_child(self):
        self.filesystem.add_object(self.root_name, self.fake_child)
        self.filesystem.add_object(self.fake_child.name, self.fake_file)
        path = self.filesystem.joinpaths(self.fake_child.name, self.fake_file.name)
        self.assertTrue(self.filesystem.exists(path))

    def test_get_object_from_child(self):
        self.filesystem.add_object(self.root_name, self.fake_child)
        self.filesystem.add_object(self.fake_child.name, self.fake_file)
        self.assertEqual(
            self.fake_file,
            self.filesystem.get_object(
                self.filesystem.joinpaths(self.fake_child.name, self.fake_file.name)
            ),
        )

    def test_get_nonexistent_object_from_child_error(self):
        self.filesystem.add_object(self.root_name, self.fake_child)
        self.filesystem.add_object(self.fake_child.name, self.fake_file)
        with self.raises_os_error(errno.ENOENT):
            self.filesystem.get_object(
                self.filesystem.joinpaths(self.fake_child.name, "some_bogus_filename")
            )

    def test_remove_object_from_child(self):
        self.filesystem.add_object(self.root_name, self.fake_child)
        self.filesystem.add_object(self.fake_child.name, self.fake_file)
        target_path = self.filesystem.joinpaths(
            self.fake_child.name, self.fake_file.name
        )
        self.filesystem.remove_object(target_path)
        with self.raises_os_error(errno.ENOENT):
            self.filesystem.get_object(target_path)

    def test_remove_object_from_child_error(self):
        self.filesystem.add_object(self.root_name, self.fake_child)
        with self.raises_os_error(errno.ENOENT):
            self.filesystem.remove_object(
                self.filesystem.joinpaths(self.fake_child.name, "some_bogus_filename")
            )

    def test_remove_object_from_non_directory_error(self):
        self.filesystem.add_object(self.root_name, self.fake_file)
        with self.raises_os_error(errno.ENOTDIR):
            self.filesystem.remove_object(
                self.filesystem.joinpaths(
                    "%s" % self.fake_file.name,
                    "file_does_not_matter_since_parent_not_a_directory",
                )
            )

    def test_exists_file_removed_from_child(self):
        self.filesystem.add_object(self.root_name, self.fake_child)
        self.filesystem.add_object(self.fake_child.name, self.fake_file)
        path = self.filesystem.joinpaths(self.fake_child.name, self.fake_file.name)
        self.filesystem.remove_object(path)
        self.assertFalse(self.filesystem.exists(path))

    def test_operate_on_grandchild_directory(self):
        self.filesystem.add_object(self.root_name, self.fake_child)
        self.filesystem.add_object(self.fake_child.name, self.fake_grandchild)
        grandchild_directory = self.filesystem.joinpaths(
            self.fake_child.name, self.fake_grandchild.name
        )
        grandchild_file = self.filesystem.joinpaths(
            grandchild_directory, self.fake_file.name
        )
        with self.assertRaises(OSError):
            self.filesystem.get_object(grandchild_file)
        self.filesystem.add_object(grandchild_directory, self.fake_file)
        self.assertEqual(self.fake_file, self.filesystem.get_object(grandchild_file))
        self.assertTrue(self.filesystem.exists(grandchild_file))
        self.filesystem.remove_object(grandchild_file)
        with self.assertRaises(OSError):
            self.filesystem.get_object(grandchild_file)
        self.assertFalse(self.filesystem.exists(grandchild_file))

    def test_create_directory_in_root_directory(self):
        path = "foo"
        self.filesystem.create_dir(path)
        new_dir = self.filesystem.get_object(path)
        self.assertEqual(os.path.basename(path), new_dir.name)
        self.assertTrue(stat.S_IFDIR & new_dir.st_mode)

    def test_create_directory_in_root_directory_already_exists_error(self):
        path = "foo"
        self.filesystem.create_dir(path)
        with self.raises_os_error(errno.EEXIST):
            self.filesystem.create_dir(path)

    def test_create_directory(self):
        path = "foo/bar/baz"
        self.filesystem.create_dir(path)
        new_dir = self.filesystem.get_object(path)
        self.assertEqual(os.path.basename(path), new_dir.name)
        self.assertTrue(stat.S_IFDIR & new_dir.st_mode)

        # Create second directory to make sure first is OK.
        path = "%s/quux" % path
        self.filesystem.create_dir(path)
        new_dir = self.filesystem.get_object(path)
        self.assertEqual(os.path.basename(path), new_dir.name)
        self.assertTrue(stat.S_IFDIR & new_dir.st_mode)

    def test_create_directory_already_exists_error(self):
        path = "foo/bar/baz"
        self.filesystem.create_dir(path)
        with self.raises_os_error(errno.EEXIST):
            self.filesystem.create_dir(path)

    def test_create_file_in_read_only_directory_raises_in_posix(self):
        self.filesystem.is_windows_fs = False
        dir_path = "/foo/bar"
        self.filesystem.create_dir(dir_path, perm_bits=0o555)
        file_path = dir_path + "/baz"

        if not is_root():
            with self.raises_os_error(errno.EACCES):
                self.filesystem.create_file(file_path)
        else:
            self.filesystem.create_file(file_path)
            self.assertTrue(self.filesystem.exists(file_path))

    def test_create_file_in_read_only_directory_possible_in_windows(self):
        self.filesystem.is_windows_fs = True
        dir_path = "C:/foo/bar"
        self.filesystem.create_dir(dir_path, perm_bits=0o555)
        file_path = dir_path + "/baz"
        self.filesystem.create_file(file_path)
        self.assertTrue(self.filesystem.exists(file_path))

    def test_create_file_in_current_directory(self):
        path = "foo"
        contents = "dummy data"
        self.filesystem.create_file(path, contents=contents)
        self.assertTrue(self.filesystem.exists(path))
        self.assertFalse(self.filesystem.exists(os.path.dirname(path)))
        path = "./%s" % path
        self.assertTrue(self.filesystem.exists(os.path.dirname(path)))

    def test_create_file_in_root_directory(self):
        path = "/foo"
        contents = "dummy data"
        self.filesystem.create_file(path, contents=contents)
        new_file = self.filesystem.get_object(path)
        self.assertTrue(self.filesystem.exists(path))
        self.assertTrue(self.filesystem.exists(os.path.dirname(path)))
        self.assertEqual(os.path.basename(path), new_file.name)
        self.assertTrue(stat.S_IFREG & new_file.st_mode)
        self.assertEqual(contents, new_file.contents)

    def test_create_file_with_size_but_no_content_creates_large_file(self):
        path = "large_foo_bar"
        self.filesystem.create_file(path, st_size=100000000)
        new_file = self.filesystem.get_object(path)
        self.assertEqual(None, new_file.contents)
        self.assertEqual(100000000, new_file.st_size)

    def test_create_file_in_root_directory_already_exists_error(self):
        path = "foo"
        self.filesystem.create_file(path)
        with self.raises_os_error(errno.EEXIST):
            self.filesystem.create_file(path)

    def test_create_file(self):
        path = "foo/bar/baz"
        retval = self.filesystem.create_file(path, contents="dummy_data")
        self.assertTrue(self.filesystem.exists(path))
        self.assertTrue(self.filesystem.exists(os.path.dirname(path)))
        new_file = self.filesystem.get_object(path)
        self.assertEqual(os.path.basename(path), new_file.name)
        if IS_WIN:
            self.assertEqual(1, new_file.st_uid)
            self.assertEqual(1, new_file.st_gid)
        else:
            self.assertEqual(os.getuid(), new_file.st_uid)
            self.assertEqual(os.getgid(), new_file.st_gid)
        self.assertEqual(new_file, retval)

    def test_create_file_with_changed_ids(self):
        path = "foo/bar/baz"
        set_uid(42)
        set_gid(2)
        self.filesystem.create_file(path)
        self.assertTrue(self.filesystem.exists(path))
        new_file = self.filesystem.get_object(path)
        self.assertEqual(42, new_file.st_uid)
        self.assertEqual(2, new_file.st_gid)
        reset_ids()

    def test_empty_file_created_for_none_contents(self):
        fake_open = fake_filesystem.FakeFileOpen(self.filesystem)
        path = "foo/bar/baz"
        self.filesystem.create_file(path, contents=None)
        with fake_open(path) as f:
            self.assertEqual("", f.read())

    def test_create_file_with_incorrect_mode_type(self):
        with self.assertRaises(TypeError):
            self.filesystem.create_file("foo", "bar")

    def test_create_file_already_exists_error(self):
        path = "foo/bar/baz"
        self.filesystem.create_file(path, contents="dummy_data")
        with self.raises_os_error(errno.EEXIST):
            self.filesystem.create_file(path)

    def test_create_link(self):
        path = "foo/bar/baz"
        target_path = "foo/bar/quux"
        new_file = self.filesystem.create_symlink(path, "quux")
        # Neither the path nor the final target exists before we actually
        # write to one of them, even though the link appears in the file
        # system.
        self.assertFalse(self.filesystem.exists(path))
        self.assertFalse(self.filesystem.exists(target_path))
        self.assertTrue(stat.S_IFLNK & new_file.st_mode)

        # but once we write the linked to file, they both will exist.
        self.filesystem.create_file(target_path)
        self.assertTrue(self.filesystem.exists(path))
        self.assertTrue(self.filesystem.exists(target_path))

    def test_resolve_object(self):
        target_path = "dir/target"
        target_contents = "0123456789ABCDEF"
        link_name = "x"
        self.filesystem.create_dir("dir")
        self.filesystem.create_file("dir/target", contents=target_contents)
        self.filesystem.create_symlink(link_name, target_path)
        obj = self.filesystem.resolve(link_name)
        self.assertEqual("target", obj.name)
        self.assertEqual(target_contents, obj.contents)

    def check_lresolve_object(self):
        target_path = "dir/target"
        target_contents = "0123456789ABCDEF"
        link_name = "x"
        self.filesystem.create_dir("dir")
        self.filesystem.create_file("dir/target", contents=target_contents)
        self.filesystem.create_symlink(link_name, target_path)
        obj = self.filesystem.lresolve(link_name)
        self.assertEqual(link_name, obj.name)
        self.assertEqual(target_path, obj.contents)

    def test_lresolve_object_windows(self):
        self.filesystem.is_windows_fs = True
        self.check_lresolve_object()

    def test_lresolve_object_posix(self):
        self.filesystem.is_windows_fs = False
        self.check_lresolve_object()

    def check_directory_access_on_file(self, error_subtype):
        self.filesystem.create_file("not_a_dir")
        with self.raises_os_error(error_subtype):
            self.filesystem.resolve("not_a_dir/foo")
        with self.raises_os_error(error_subtype):
            self.filesystem.lresolve("not_a_dir/foo/bar")

    def test_directory_access_on_file_windows(self):
        self.filesystem.is_windows_fs = True
        self.check_directory_access_on_file(errno.ENOENT)

    def test_directory_access_on_file_posix(self):
        self.filesystem.is_windows_fs = False
        self.check_directory_access_on_file(errno.ENOTDIR)

    def test_pickle_fs(self):
        """Regression test for #445"""
        import pickle

        self.filesystem.open_files = []
        p = pickle.dumps(self.filesystem)
        fs = pickle.loads(p)
        self.assertEqual(str(fs.root), str(self.filesystem.root))
        self.assertEqual(fs.mount_points, self.filesystem.mount_points)


class CaseInsensitiveFakeFilesystemTest(TestCase):
    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(path_separator="/")
        self.filesystem.is_case_sensitive = False
        self.os = fake_os.FakeOsModule(self.filesystem)
        self.path = self.os.path

    def test_get_object(self):
        self.filesystem.create_dir("/foo/bar")
        self.filesystem.create_file("/foo/bar/baz")
        self.assertTrue(self.filesystem.get_object("/Foo/Bar/Baz"))

    def test_remove_object(self):
        self.filesystem.create_dir("/foo/bar")
        self.filesystem.create_file("/foo/bar/baz")
        self.filesystem.remove_object("/Foo/Bar/Baz")
        self.assertFalse(self.filesystem.exists("/foo/bar/baz"))

    def test_exists(self):
        self.filesystem.create_dir("/Foo/Bar")
        self.assertTrue(self.filesystem.exists("/Foo/Bar"))
        self.assertTrue(self.filesystem.exists("/foo/bar"))

        self.filesystem.create_file("/foo/Bar/baz")
        self.assertTrue(self.filesystem.exists("/Foo/bar/BAZ"))
        self.assertTrue(self.filesystem.exists("/foo/bar/baz"))

    def test_create_directory_with_different_case_root(self):
        self.filesystem.create_dir("/Foo/Bar")
        self.filesystem.create_dir("/foo/bar/baz")
        dir1 = self.filesystem.get_object("/Foo/Bar")
        dir2 = self.filesystem.get_object("/foo/bar")
        self.assertEqual(dir1, dir2)

    def test_create_file_with_different_case_dir(self):
        self.filesystem.create_dir("/Foo/Bar")
        self.filesystem.create_file("/foo/bar/baz")
        dir1 = self.filesystem.get_object("/Foo/Bar")
        dir2 = self.filesystem.get_object("/foo/bar")
        self.assertEqual(dir1, dir2)

    def test_resolve_path(self):
        self.filesystem.create_dir("/foo/baz")
        self.filesystem.create_symlink("/Foo/Bar", "./baz/bip")
        self.assertEqual(
            f"{self.filesystem.root_dir_name}foo/baz/bip",
            self.filesystem.resolve_path("/foo/bar"),
        )

    def test_isdir_isfile(self):
        self.filesystem.create_file("foo/bar")
        self.assertTrue(self.path.isdir("Foo"))
        self.assertFalse(self.path.isfile("Foo"))
        self.assertTrue(self.path.isfile("Foo/Bar"))
        self.assertFalse(self.path.isdir("Foo/Bar"))

    def test_getsize(self):
        file_path = "foo/bar/baz"
        self.filesystem.create_file(file_path, contents="1234567")
        self.assertEqual(7, self.path.getsize("FOO/BAR/BAZ"))

    def test_getsize_with_looping_symlink(self):
        self.filesystem.is_windows_fs = False
        dir_path = "/foo/bar"
        self.filesystem.create_dir(dir_path)
        link_path = dir_path + "/link"
        link_target = link_path + "/link"
        self.os.symlink(link_target, link_path)
        with self.raises_os_error(errno.ELOOP):
            self.os.path.getsize(link_path)

    def test_get_mtime(self):
        test_file = self.filesystem.create_file("foo/bar1.txt")
        test_file.st_mtime = 24
        self.assertEqual(24, self.path.getmtime("Foo/Bar1.TXT"))

    def test_get_object_with_file_size(self):
        self.filesystem.create_file("/Foo/Bar", st_size=10)
        self.assertTrue(self.filesystem.get_object("/foo/bar"))


class CaseSensitiveFakeFilesystemTest(TestCase):
    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(path_separator="/")
        self.filesystem.is_case_sensitive = True
        self.os = fake_os.FakeOsModule(self.filesystem)
        self.path = self.os.path

    def test_get_object(self):
        self.filesystem.create_dir("/foo/bar")
        self.filesystem.create_file("/foo/bar/baz")
        with self.assertRaises(OSError):
            self.filesystem.get_object("/Foo/Bar/Baz")

    def test_remove_object(self):
        self.filesystem.create_dir("/foo/bar")
        self.filesystem.create_file("/foo/bar/baz")
        with self.assertRaises(OSError):
            self.filesystem.remove_object("/Foo/Bar/Baz")
        self.assertTrue(self.filesystem.exists("/foo/bar/baz"))

    def test_exists(self):
        self.filesystem.create_dir("/Foo/Bar")
        self.assertTrue(self.filesystem.exists("/Foo/Bar"))
        self.assertFalse(self.filesystem.exists("/foo/bar"))

        self.filesystem.create_file("/foo/Bar/baz")
        self.assertFalse(self.filesystem.exists("/Foo/bar/BAZ"))
        self.assertFalse(self.filesystem.exists("/foo/bar/baz"))

    def test_create_directory_with_different_case_root(self):
        self.filesystem.create_dir("/Foo/Bar")
        self.filesystem.create_dir("/foo/bar/baz")
        dir1 = self.filesystem.get_object("/Foo/Bar")
        dir2 = self.filesystem.get_object("/foo/bar")
        self.assertNotEqual(dir1, dir2)

    def test_create_file_with_different_case_dir(self):
        self.filesystem.create_dir("/Foo/Bar")
        self.filesystem.create_file("/foo/bar/baz")
        dir1 = self.filesystem.get_object("/Foo/Bar")
        dir2 = self.filesystem.get_object("/foo/bar")
        self.assertNotEqual(dir1, dir2)

    def test_isdir_isfile(self):
        self.filesystem.create_file("foo/bar")
        self.assertFalse(self.path.isdir("Foo"))
        self.assertFalse(self.path.isfile("Foo"))
        self.assertFalse(self.path.isfile("Foo/Bar"))
        self.assertFalse(self.path.isdir("Foo/Bar"))

    def test_getsize(self):
        file_path = "foo/bar/baz"
        self.filesystem.create_file(file_path, contents="1234567")
        with self.assertRaises(os.error):
            self.path.getsize("FOO/BAR/BAZ")

    def test_get_mtime(self):
        test_file = self.filesystem.create_file("foo/bar1.txt")
        test_file.st_mtime = 24
        with self.raises_os_error(errno.ENOENT):
            self.path.getmtime("Foo/Bar1.TXT")


class OsPathInjectionRegressionTest(TestCase):
    """Test faking os.path before calling os.walk.

    Found when investigating a problem with
    gws/tools/labrat/rat_utils_unittest, which was faking out os.path
    before calling os.walk.
    """

    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(path_separator="/")
        self.os_path = os.path
        # The bug was that when os.path gets faked, the FakePathModule doesn't
        # get called in self.os.walk(). FakePathModule now insists that it is
        # created as part of FakeOsModule.
        self.os = fake_os.FakeOsModule(self.filesystem)

    def tearDown(self):
        os.path = self.os_path

    def test_create_top_level_directory(self):
        top_level_dir = "/x"
        self.assertFalse(self.filesystem.exists(top_level_dir))
        self.filesystem.create_dir(top_level_dir)
        self.assertTrue(self.filesystem.exists("/"))
        self.assertTrue(self.filesystem.exists(top_level_dir))
        self.filesystem.create_dir("%s/po" % top_level_dir)
        self.filesystem.create_file("%s/po/control" % top_level_dir)
        self.filesystem.create_file("%s/po/experiment" % top_level_dir)
        self.filesystem.create_dir("%s/gv" % top_level_dir)
        self.filesystem.create_file("%s/gv/control" % top_level_dir)

        expected = [
            ("/", ["x"], []),
            ("/x", ["gv", "po"], []),
            ("/x/gv", [], ["control"]),
            ("/x/po", [], ["control", "experiment"]),
        ]
        # as the result is unsorted, we have to check against sorted results
        result = sorted([step for step in self.os.walk("/")], key=lambda v: v[0])
        self.assertEqual(len(expected), len(result))
        for entry, expected_entry in zip(result, expected):
            self.assertEqual(expected_entry[0], entry[0])
            self.assertEqual(expected_entry[1], sorted(entry[1]))
            self.assertEqual(expected_entry[2], sorted(entry[2]))


class FakePathModuleTest(TestCase):
    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(path_separator="!")
        self.os = fake_os.FakeOsModule(self.filesystem)
        self.path = self.os.path

    def check_abspath(self, is_windows):
        # the implementation differs in Windows and Posix, so test both
        self.filesystem.is_windows_fs = is_windows
        filename = "foo"
        abspath = self.filesystem.root_dir_name + filename
        self.filesystem.create_file(abspath)
        self.assertEqual(abspath, self.path.abspath(abspath))
        self.assertEqual(abspath, self.path.abspath(filename))
        self.assertEqual(abspath, self.path.abspath("..!%s" % filename))

    def test_abspath_windows(self):
        self.check_abspath(is_windows=True)

    def test_abspath_posix(self):
        """abspath should return a consistent representation of a file."""
        self.check_abspath(is_windows=False)

    def check_abspath_bytes(self, is_windows):
        """abspath should return a consistent representation of a file."""
        self.filesystem.is_windows_fs = is_windows
        filename = b"foo"
        abspath = self.filesystem.root_dir_name.encode() + filename
        self.filesystem.create_file(abspath)
        self.assertEqual(abspath, self.path.abspath(abspath))
        self.assertEqual(abspath, self.path.abspath(filename))
        self.assertEqual(abspath, self.path.abspath(b"..!" + filename))

    def test_abspath_bytes_windows(self):
        self.check_abspath_bytes(is_windows=True)

    def test_abspath_bytes_posix(self):
        self.check_abspath_bytes(is_windows=False)

    def test_abspath_deals_with_relative_non_root_path(self):
        """abspath should correctly handle relative paths from a
        non-! directory.

        This test is distinct from the basic functionality test because
        fake_filesystem has historically been based in !.
        """
        filename = "!foo!bar!baz"
        file_components = filename.split(self.path.sep)
        root_name = self.filesystem.root_dir_name
        basedir = f"{root_name}{file_components[0]}"
        self.filesystem.create_file(filename)
        self.os.chdir(basedir)
        self.assertEqual(basedir, self.path.abspath(self.path.curdir))
        self.assertEqual(root_name, self.path.abspath(".."))
        self.assertEqual(
            self.path.join(basedir, file_components[1]),
            self.path.abspath(file_components[1]),
        )

    def test_abs_path_with_drive_component(self):
        self.filesystem.is_windows_fs = True
        self.filesystem.cwd = "C:!foo"
        self.assertEqual("C:!foo!bar", self.path.abspath("bar"))
        self.assertEqual("C:!foo!bar", self.path.abspath("C:bar"))
        self.assertEqual("C:!foo!bar", self.path.abspath("!foo!bar"))

    def test_isabs_with_drive_component(self):
        self.filesystem.is_windows_fs = False
        self.assertFalse(self.path.isabs("C:!foo"))
        self.assertFalse(self.path.isabs(b"C:!foo"))
        self.assertTrue(self.path.isabs("!"))
        self.assertTrue(self.path.isabs(b"!"))
        self.filesystem.is_windows_fs = True
        self.assertTrue(self.path.isabs("C:!foo"))
        self.assertTrue(self.path.isabs(b"C:!foo"))
        self.assertTrue(self.path.isabs("!"))
        self.assertTrue(self.path.isabs(b"!"))

    def test_relpath(self):
        path_foo = "!path!to!foo"
        path_bar = "!path!to!bar"
        path_other = "!some!where!else"
        with self.assertRaises(ValueError):
            self.path.relpath(None)
        with self.assertRaises(ValueError):
            self.path.relpath("")
        self.assertEqual("path!to!foo", self.path.relpath(path_foo))
        self.assertEqual("..!foo", self.path.relpath(path_foo, path_bar))
        self.assertEqual(
            "..!..!..%s" % path_other, self.path.relpath(path_other, path_bar)
        )
        self.assertEqual(".", self.path.relpath(path_bar, path_bar))

    def test_realpath_vs_abspath(self):
        self.filesystem.is_windows_fs = False
        self.filesystem.create_file("!george!washington!bridge")
        self.filesystem.create_symlink("!first!president", "!george!washington")
        self.assertEqual(
            "!first!president!bridge",
            self.os.path.abspath("!first!president!bridge"),
        )
        self.assertEqual(
            "!george!washington!bridge",
            self.os.path.realpath("!first!president!bridge"),
        )
        self.os.chdir("!first!president")
        self.assertEqual("!george!washington!bridge", self.os.path.realpath("bridge"))

    @unittest.skipIf(sys.version_info < (3, 10), "'strict' new in Python 3.10")
    def test_realpath_strict(self):
        self.filesystem.create_file("!foo!bar")
        root_dir = self.filesystem.root_dir_name
        self.filesystem.cwd = f"{root_dir}foo"
        self.assertEqual(
            f"{root_dir}foo!baz", self.os.path.realpath("baz", strict=False)
        )
        with self.raises_os_error(errno.ENOENT):
            self.os.path.realpath("baz", strict=True)
        self.assertEqual(
            f"{root_dir}foo!bar", self.os.path.realpath("bar", strict=True)
        )

    def test_samefile(self):
        file_path1 = "!foo!bar!baz"
        file_path2 = "!foo!bar!boo"
        self.filesystem.create_file(file_path1)
        self.filesystem.create_file(file_path2)
        self.assertTrue(self.path.samefile(file_path1, file_path1))
        self.assertFalse(self.path.samefile(file_path1, file_path2))
        self.assertTrue(self.path.samefile(file_path1, "!foo!..!foo!bar!..!bar!baz"))
        self.assertTrue(self.path.samefile(file_path1, b"!foo!..!foo!bar!..!bar!baz"))

    def test_exists(self):
        file_path = "foo!bar!baz"
        file_path_bytes = b"foo!bar!baz"
        self.filesystem.create_file(file_path)
        self.assertTrue(self.path.exists(file_path))
        self.assertTrue(self.path.exists(file_path_bytes))
        self.assertFalse(self.path.exists("!some!other!bogus!path"))

    def test_exists_with_drive(self):
        self.filesystem.os = OSType.WINDOWS
        self.filesystem.add_mount_point("F:")
        self.assertTrue(self.path.exists("C:"))
        self.assertTrue(self.path.exists("c:\\"))
        self.assertTrue(self.path.exists("f:"))
        self.assertTrue(self.path.exists("F:\\"))
        self.assertFalse(self.path.exists("Z:"))
        self.assertFalse(self.path.exists("z:\\"))

    def test_lexists(self):
        file_path = "foo!bar!baz"
        file_path_bytes = b"foo!bar!baz"
        self.filesystem.create_dir("foo!bar")
        self.filesystem.create_symlink(file_path, "bogus")
        self.assertTrue(self.path.lexists(file_path))
        self.assertTrue(self.path.lexists(file_path_bytes))
        self.assertFalse(self.path.exists(file_path))
        self.assertFalse(self.path.exists(file_path_bytes))
        self.filesystem.create_file("foo!bar!bogus")
        self.assertTrue(self.path.exists(file_path))

    def test_dirname_with_drive(self):
        self.filesystem.is_windows_fs = True
        self.assertEqual("c:!foo", self.path.dirname("c:!foo!bar"))
        self.assertEqual(b"c:!", self.path.dirname(b"c:!foo"))
        self.assertEqual("!foo", self.path.dirname("!foo!bar"))
        self.assertEqual(b"!", self.path.dirname(b"!foo"))
        self.assertEqual("c:foo", self.path.dirname("c:foo!bar"))
        self.assertEqual(b"c:", self.path.dirname(b"c:foo"))
        self.assertEqual("foo", self.path.dirname("foo!bar"))

    def test_dirname(self):
        dirname = "foo!bar"
        self.assertEqual(dirname, self.path.dirname("%s!baz" % dirname))

    def test_join_strings(self):
        components = ["foo", "bar", "baz"]
        self.assertEqual("foo!bar!baz", self.path.join(*components))

    def test_join_bytes(self):
        components = [b"foo", b"bar", b"baz"]
        self.assertEqual(b"foo!bar!baz", self.path.join(*components))

    @unittest.skipIf(sys.platform != "win32", "Windows specific test")
    @patch.dict(os.environ, {"USERPROFILE": r"C:\Users\John"})
    def test_expand_user_windows(self):
        self.assertEqual(self.path.expanduser("~"), "C:!Users!John")

    @unittest.skipIf(sys.platform == "win32", "Posix specific test")
    @patch.dict(os.environ, {"HOME": "/home/john"})
    def test_expand_user(self):
        self.assertEqual(self.path.expanduser("~"), "!home!john")

    @patch.dict(os.environ, {}, clear=True)
    def test_expand_user_no_home_environment(self):
        """Make sure this also works without HOME / USERPROFILE set"""
        # we just check that it does not crash and has some result,
        # as the result is system-dependent
        self.assertTrue(self.path.expanduser("~"))

    @unittest.skipIf(
        TestCase.is_windows or TestCase.is_cygwin,
        "only tested on unix systems",
    )
    def test_expand_root(self):
        if sys.platform == "darwin":
            roothome = "!var!root"
        else:
            roothome = "!root"
        self.assertEqual(self.path.expanduser("~root"), roothome)

    def test_getsize_path_nonexistent(self):
        file_path = "foo!bar!baz"
        with self.assertRaises(os.error):
            self.path.getsize(file_path)

    def test_getsize_file_empty(self):
        file_path = "foo!bar!baz"
        self.filesystem.create_file(file_path)
        self.assertEqual(0, self.path.getsize(file_path))

    def test_getsize_file_non_zero_size(self):
        file_path = "foo!bar!baz"
        file_path_bytes = b"foo!bar!baz"
        self.filesystem.create_file(file_path, contents="1234567")
        self.assertEqual(7, self.path.getsize(file_path))
        self.assertEqual(7, self.path.getsize(file_path_bytes))

    def test_getsize_dir_empty(self):
        # For directories, only require that the size is non-negative.
        dir_path = "foo!bar"
        self.filesystem.create_dir(dir_path)
        size = self.path.getsize(dir_path)
        self.assertFalse(int(size) < 0, "expected non-negative size; actual: %s" % size)

    def test_getsize_dir_non_zero_size(self):
        # For directories, only require that the size is non-negative.
        dir_path = "foo!bar"
        self.filesystem.create_file(self.filesystem.joinpaths(dir_path, "baz"))
        size = self.path.getsize(dir_path)
        self.assertFalse(int(size) < 0, "expected non-negative size; actual: %s" % size)

    def test_isdir(self):
        self.filesystem.create_file("foo!bar")
        self.assertTrue(self.path.isdir("foo"))
        self.assertTrue(self.path.isdir(b"foo"))
        self.assertFalse(self.path.isdir("foo!bar"))
        self.assertFalse(self.path.isdir("it_dont_exist"))

    def test_isdir_with_cwd_change(self):
        self.filesystem.create_file("!foo!bar!baz")
        self.assertTrue(self.path.isdir("!foo"))
        self.assertTrue(self.path.isdir("!foo!bar"))
        self.assertTrue(self.path.isdir("foo"))
        self.assertTrue(self.path.isdir("foo!bar"))
        self.filesystem.cwd = f"{self.filesystem.root_dir_name}foo"
        self.assertTrue(self.path.isdir("!foo"))
        self.assertTrue(self.path.isdir("!foo!bar"))
        self.assertTrue(self.path.isdir("bar"))

    def test_isfile(self):
        self.filesystem.create_file("foo!bar")
        self.assertFalse(self.path.isfile("foo"))
        self.assertTrue(self.path.isfile("foo!bar"))
        self.assertTrue(self.path.isfile(b"foo!bar"))
        self.assertFalse(self.path.isfile("it_dont_exist"))

    def test_get_mtime(self):
        test_file = self.filesystem.create_file("foo!bar1.txt")
        self.assertNotEqual(24, self.path.getmtime("foo!bar1.txt"))
        test_file.st_mtime = 24
        self.assertEqual(24, self.path.getmtime("foo!bar1.txt"))
        self.assertEqual(24, self.path.getmtime(b"foo!bar1.txt"))

    def test_get_mtime_raises_os_error(self):
        self.assertFalse(self.path.exists("does_not_exist"))
        with self.raises_os_error(errno.ENOENT):
            self.path.getmtime("does_not_exist")

    def test_islink(self):
        self.filesystem.create_dir("foo")
        self.filesystem.create_file("foo!regular_file")
        self.filesystem.create_symlink("foo!link_to_file", "regular_file")
        self.assertFalse(self.path.islink("foo"))

        # An object can be both a link and a file or file, according to the
        # comments in Python/Lib/posixpath.py.
        self.assertTrue(self.path.islink("foo!link_to_file"))
        self.assertTrue(self.path.isfile("foo!link_to_file"))
        self.assertTrue(self.path.islink(b"foo!link_to_file"))
        self.assertTrue(self.path.isfile(b"foo!link_to_file"))

        self.assertTrue(self.path.isfile("foo!regular_file"))
        self.assertFalse(self.path.islink("foo!regular_file"))

        self.assertFalse(self.path.islink("it_dont_exist"))

    def test_is_link_case_sensitive(self):
        # Regression test for #306
        self.filesystem.is_case_sensitive = False
        self.filesystem.create_dir("foo")
        self.filesystem.create_symlink("foo!bar", "foo")
        self.assertTrue(self.path.islink("foo!Bar"))

    def test_ismount(self):
        self.assertFalse(self.path.ismount(""))
        self.assertTrue(self.path.ismount("!"))
        self.assertTrue(self.path.ismount(b"!"))
        self.assertFalse(self.path.ismount("!mount!"))
        self.filesystem.add_mount_point("!mount")
        self.assertTrue(self.path.ismount("!mount"))
        self.assertTrue(self.path.ismount(b"!mount"))
        self.assertTrue(self.path.ismount("!mount!"))

    def test_ismount_with_drive_letters(self):
        self.filesystem.is_windows_fs = True
        self.assertTrue(self.path.ismount("!"))
        self.assertTrue(self.path.ismount("c:!"))
        self.assertFalse(self.path.ismount("c:"))
        self.assertTrue(self.path.ismount("z:!"))
        self.filesystem.add_mount_point("!mount")
        self.assertTrue(self.path.ismount("!mount"))
        self.assertTrue(self.path.ismount("!mount!"))

    def test_ismount_with_unc_paths(self):
        self.filesystem.is_windows_fs = True
        self.assertTrue(self.path.ismount("!!a!"))
        self.assertTrue(self.path.ismount("!!a!b"))
        self.assertTrue(self.path.ismount("!!a!b!"))
        self.assertFalse(self.path.ismount("!a!b!"))
        self.assertFalse(self.path.ismount("!!a!b!c"))

    def test_ismount_with_alternate_path_separator(self):
        self.filesystem.alternative_path_separator = "!"
        self.filesystem.add_mount_point("!mount")
        self.assertTrue(self.path.ismount("!mount"))
        self.assertTrue(self.path.ismount("!mount!"))
        self.assertTrue(self.path.ismount("!mount!!"))
        self.filesystem.is_windows_fs = True
        self.assertTrue(self.path.ismount("Z:!"))

    def test_getattr_forward_to_real_os_path(self):
        """Forwards any non-faked calls to os.path."""
        self.assertTrue(hasattr(self.path, "sep"), "Get a faked os.path function")
        private_path_function = None
        if sys.version_info < (3, 6):
            if self.is_windows:
                private_path_function = "_get_bothseps"
            else:
                private_path_function = "_join_real_path"
        if private_path_function:
            self.assertTrue(
                hasattr(self.path, private_path_function),
                "Get a real os.path function " "not implemented in fake os.path",
            )
        self.assertFalse(hasattr(self.path, "nonexistent"))

    def test_splitroot_posix(self):
        self.filesystem.is_windows_fs = False
        self.assertEqual(("", "", "foo!bar"), self.filesystem.splitroot("foo!bar"))
        self.assertEqual(("", "!", "foo!bar"), self.filesystem.splitroot("!foo!bar"))
        self.assertEqual(
            ("", "!!", "foo!!bar"), self.filesystem.splitroot("!!foo!!bar")
        )


class PathManipulationTestBase(TestCase):
    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(path_separator="|")


class CollapsePathPipeSeparatorTest(PathManipulationTestBase):
    """Tests CollapsePath (mimics os.path.normpath) using |
    as path separator."""

    def test_empty_path_becomes_dot_path(self):
        self.assertEqual(".", self.filesystem.normpath(""))

    def test_dot_path_unchanged(self):
        self.assertEqual(".", self.filesystem.normpath("."))

    def test_slashes_are_not_collapsed(self):
        """Tests that '/' is not treated specially if the
            path separator is '|'.

        In particular, multiple slashes should not be collapsed.
        """
        self.assertEqual("/", self.filesystem.normpath("/"))
        self.assertEqual("/////", self.filesystem.normpath("/////"))

    def test_root_path(self):
        self.assertEqual("|", self.filesystem.normpath("|"))

    def test_multiple_separators_collapsed_into_root_path(self):
        self.assertEqual("|", self.filesystem.normpath("|||||"))

    def test_all_dot_paths_removed_but_one(self):
        self.assertEqual(".", self.filesystem.normpath(".|.|.|."))

    def test_all_dot_paths_removed_if_another_path_component_exists(self):
        self.assertEqual("|", self.filesystem.normpath("|.|.|.|"))
        self.assertEqual("foo|bar", self.filesystem.normpath("foo|.|.|.|bar"))

    def test_ignores_up_level_references_starting_from_root(self):
        self.assertEqual("|", self.filesystem.normpath("|..|..|..|"))
        self.assertEqual("|", self.filesystem.normpath("|..|..|foo|bar|..|..|"))
        self.filesystem.is_windows_fs = False  # not an UNC path
        self.assertEqual("|", self.filesystem.normpath("||..|.|..||"))

    def test_conserves_up_level_references_starting_from_current_dir(self):
        self.assertEqual("..|..", self.filesystem.normpath("..|foo|bar|..|..|.."))

    def test_combine_dot_and_up_level_references_in_absolute_path(self):
        self.assertEqual("|yes", self.filesystem.normpath("|||||.|..|||yes|no|..|.|||"))

    def test_dots_in_path_collapses_to_last_path(self):
        self.assertEqual("bar", self.filesystem.normpath("foo|..|bar"))
        self.assertEqual("bar", self.filesystem.normpath("foo|..|yes|..|no|..|bar"))


class SplitPathTest(PathManipulationTestBase):
    """Tests SplitPath (which mimics os.path.split)
    using | as path separator."""

    def test_empty_path(self):
        self.assertEqual(("", ""), self.filesystem.splitpath(""))

    def test_no_separators(self):
        self.assertEqual(("", "ab"), self.filesystem.splitpath("ab"))

    def test_slashes_do_not_split(self):
        """Tests that '/' is not treated specially if the
        path separator is '|'."""
        self.assertEqual(("", "a/b"), self.filesystem.splitpath("a/b"))

    def test_eliminate_trailing_separators_from_head(self):
        self.assertEqual(("a", "b"), self.filesystem.splitpath("a|b"))
        self.assertEqual(("a", "b"), self.filesystem.splitpath("a|||b"))
        self.assertEqual(("|a", "b"), self.filesystem.splitpath("|a||b"))
        self.assertEqual(("a|b", "c"), self.filesystem.splitpath("a|b|c"))
        self.assertEqual(("|a|b", "c"), self.filesystem.splitpath("|a|b|c"))

    def test_root_separator_is_not_stripped(self):
        self.assertEqual(("|||", ""), self.filesystem.splitpath("|||"))
        self.assertEqual(("|", "a"), self.filesystem.splitpath("|a"))
        self.assertEqual(("|||", "a"), self.filesystem.splitpath("|||a"))

    def test_empty_tail_if_path_ends_in_separator(self):
        self.assertEqual(("a|b", ""), self.filesystem.splitpath("a|b|"))

    def test_empty_path_components_are_preserved_in_head(self):
        self.assertEqual(("|a||b", "c"), self.filesystem.splitpath("|a||b||c"))


class JoinPathTest(PathManipulationTestBase):
    """Tests JoinPath (which mimics os.path.join) using | as path separator."""

    def test_one_empty_component(self):
        self.assertEqual("", self.filesystem.joinpaths(""))

    def test_multiple_empty_components(self):
        self.assertEqual("", self.filesystem.joinpaths("", "", ""))

    def test_separators_not_stripped_from_single_component(self):
        self.assertEqual("||a||", self.filesystem.joinpaths("||a||"))

    def test_one_separator_added_between_components(self):
        self.assertEqual("a|b|c|d", self.filesystem.joinpaths("a", "b", "c", "d"))

    def test_no_separator_added_for_components_ending_in_separator(self):
        self.assertEqual("a|b|c", self.filesystem.joinpaths("a|", "b|", "c"))
        self.assertEqual("a|||b|||c", self.filesystem.joinpaths("a|||", "b|||", "c"))

    def test_components_preceding_absolute_component_are_ignored(self):
        self.assertEqual("|c|d", self.filesystem.joinpaths("a", "|b", "|c", "d"))

    def test_one_separator_added_for_trailing_empty_components(self):
        self.assertEqual("a|", self.filesystem.joinpaths("a", ""))
        self.assertEqual("a|", self.filesystem.joinpaths("a", "", ""))

    def test_no_separator_added_for_leading_empty_components(self):
        self.assertEqual("a", self.filesystem.joinpaths("", "a"))

    def test_internal_empty_components_ignored(self):
        self.assertEqual("a|b", self.filesystem.joinpaths("a", "", "b"))
        self.assertEqual("a|b|", self.filesystem.joinpaths("a|", "", "b|"))


class PathSeparatorTest(TestCase):
    def test_os_path_sep_matches_fake_filesystem_separator(self):
        filesystem = fake_filesystem.FakeFilesystem(path_separator="!")
        fake_os_module = fake_os.FakeOsModule(filesystem)
        self.assertEqual("!", fake_os_module.sep)
        self.assertEqual("!", fake_os_module.path.sep)


class NormalizeCaseTest(TestCase):
    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(path_separator="/")
        self.filesystem.is_case_sensitive = False

    def test_normalize_case(self):
        self.filesystem.create_file("/Foo/Bar")
        self.assertEqual(
            f"{self.filesystem.root_dir_name}Foo/Bar",
            self.filesystem._original_path("/foo/bar"),
        )
        self.assertEqual(
            f"{self.filesystem.root_dir_name}Foo/Bar",
            self.filesystem._original_path("/FOO/BAR"),
        )

    def test_normalize_case_for_drive(self):
        self.filesystem.is_windows_fs = True
        self.filesystem.create_file("C:/Foo/Bar")
        self.assertEqual("C:/Foo/Bar", self.filesystem._original_path("c:/foo/bar"))
        self.assertEqual("C:/Foo/Bar", self.filesystem._original_path("C:/FOO/BAR"))

    def test_normalize_case_for_non_existing_file(self):
        self.filesystem.create_dir("/Foo/Bar")
        self.assertEqual(
            f"{self.filesystem.root_dir_name}Foo/Bar/baz",
            self.filesystem._original_path("/foo/bar/baz"),
        )
        self.assertEqual(
            f"{self.filesystem.root_dir_name}Foo/Bar/BAZ",
            self.filesystem._original_path("/FOO/BAR/BAZ"),
        )

    @unittest.skipIf(
        not TestCase.is_windows, "Regression test for Windows problem only"
    )
    def test_normalize_case_for_lazily_added_empty_file(self):
        # regression test for specific issue with added empty real files
        filesystem = fake_filesystem.FakeFilesystem()
        real_dir_path = os.path.split(os.path.dirname(os.path.abspath(__file__)))[0]
        filesystem.add_real_directory(real_dir_path)
        initPyPath = os.path.join(real_dir_path, "__init__.py")
        self.assertEqual(initPyPath, filesystem._original_path(initPyPath.upper()))


class AlternativePathSeparatorTest(TestCase):
    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(path_separator="!")
        self.filesystem.alternative_path_separator = "?"

    def test_initial_value(self):
        filesystem = fake_filesystem.FakeFilesystem()
        if self.is_windows:
            self.assertEqual("/", filesystem.alternative_path_separator)
        else:
            self.assertIsNone(filesystem.alternative_path_separator)

        filesystem = fake_filesystem.FakeFilesystem(path_separator="/")
        self.assertIsNone(filesystem.alternative_path_separator)

    def test_alt_sep(self):
        fake_os_module = fake_os.FakeOsModule(self.filesystem)
        self.assertEqual("?", fake_os_module.altsep)
        self.assertEqual("?", fake_os_module.path.altsep)

    def test_collapse_path_with_mixed_separators(self):
        self.assertEqual("!foo!bar", self.filesystem.normpath("!foo??bar"))

    def test_normalize_path_with_mixed_separators(self):
        path = "foo?..?bar"
        self.assertEqual(
            f"{self.filesystem.root_dir_name}bar",
            self.filesystem.absnormpath(path),
        )

    def test_exists_with_mixed_separators(self):
        self.filesystem.create_file("?foo?bar?baz")
        self.filesystem.create_file("!foo!bar!xyzzy!plugh")
        self.assertTrue(self.filesystem.exists("!foo!bar!baz"))
        self.assertTrue(self.filesystem.exists("?foo?bar?xyzzy?plugh"))


class DriveLetterSupportTest(TestCase):
    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(path_separator="!")
        self.filesystem.alternative_path_separator = "^"
        self.filesystem.is_windows_fs = True

    def test_initial_value(self):
        filesystem = fake_filesystem.FakeFilesystem()
        if self.is_windows:
            self.assertTrue(filesystem.is_windows_fs)
        else:
            self.assertFalse(filesystem.is_windows_fs)

    def test_collapse_path(self):
        self.assertEqual("c:!foo!bar", self.filesystem.normpath("c:!!foo!!bar"))

    def test_collapse_unc_path(self):
        self.assertEqual("!!foo!bar!baz", self.filesystem.normpath("!!foo!bar!!baz!!"))

    def test_normalize_path_str(self):
        self.filesystem.cwd = ""
        self.assertEqual("c:!foo!bar", self.filesystem.absnormpath("c:!foo!!bar"))
        self.filesystem.cwd = "c:!foo"
        self.assertEqual("c:!foo!bar", self.filesystem.absnormpath("bar"))

    def test_normalize_path_bytes(self):
        self.filesystem.cwd = b""
        self.assertEqual(b"c:!foo!bar", self.filesystem.absnormpath(b"c:!foo!!bar"))
        self.filesystem.cwd = b"c:!foo"
        self.assertEqual(b"c:!foo!bar", self.filesystem.absnormpath(b"bar"))

    def test_split_path_str(self):
        self.assertEqual(("c:!foo", "bar"), self.filesystem.splitpath("c:!foo!bar"))
        self.assertEqual(("c:!", "foo"), self.filesystem.splitpath("c:!foo"))
        self.assertEqual(("!foo", "bar"), self.filesystem.splitpath("!foo!bar"))
        self.assertEqual(("!", "foo"), self.filesystem.splitpath("!foo"))
        self.assertEqual(("c:foo", "bar"), self.filesystem.splitpath("c:foo!bar"))
        self.assertEqual(("c:", "foo"), self.filesystem.splitpath("c:foo"))
        self.assertEqual(("foo", "bar"), self.filesystem.splitpath("foo!bar"))

    def test_split_with_alt_separator(self):
        self.assertEqual(("a^b", "c"), self.filesystem.splitpath("a^b^c"))
        self.assertEqual(("a^b!c", "d"), self.filesystem.splitpath("a^b!c^d"))
        self.assertEqual(("a^b!c", "d"), self.filesystem.splitpath("a^b!c!d"))
        self.assertEqual((b"a^b", b"c"), self.filesystem.splitpath(b"a^b^c"))
        self.assertEqual((b"a^b!c", b"d"), self.filesystem.splitpath(b"a^b!c^d"))
        self.assertEqual((b"a^b!c", b"d"), self.filesystem.splitpath(b"a^b!c!d"))

    def test_split_path_bytes(self):
        self.assertEqual((b"c:!foo", b"bar"), self.filesystem.splitpath(b"c:!foo!bar"))
        self.assertEqual((b"c:!", b"foo"), self.filesystem.splitpath(b"c:!foo"))
        self.assertEqual((b"!foo", b"bar"), self.filesystem.splitpath(b"!foo!bar"))
        self.assertEqual((b"!", b"foo"), self.filesystem.splitpath(b"!foo"))
        self.assertEqual((b"c:foo", b"bar"), self.filesystem.splitpath(b"c:foo!bar"))
        self.assertEqual((b"c:", b"foo"), self.filesystem.splitpath(b"c:foo"))
        self.assertEqual((b"foo", b"bar"), self.filesystem.splitpath(b"foo!bar"))

    def test_characters_before_root_ignored_in_join_paths(self):
        self.assertEqual("c:d", self.filesystem.joinpaths("b", "c:", "d"))

    def test_resolve_path(self):
        self.assertEqual("C:!foo!bar", self.filesystem.resolve_path("C:!foo!bar"))

    def test_get_path_components(self):
        self.assertEqual(
            ["c:", "foo", "bar"],
            self.filesystem._path_components("c:!foo!bar"),
        )
        self.assertEqual(["c:"], self.filesystem._path_components("c:"))

    def test_split_drive_str(self):
        self.assertEqual(("c:", "!foo!bar"), self.filesystem.splitdrive("c:!foo!bar"))
        self.assertEqual(("", "!foo!bar"), self.filesystem.splitdrive("!foo!bar"))
        self.assertEqual(("c:", "foo!bar"), self.filesystem.splitdrive("c:foo!bar"))
        self.assertEqual(("", "foo!bar"), self.filesystem.splitdrive("foo!bar"))

    def test_split_drive_bytes(self):
        self.assertEqual(
            (b"c:", b"!foo!bar"), self.filesystem.splitdrive(b"c:!foo!bar")
        )
        self.assertEqual((b"", b"!foo!bar"), self.filesystem.splitdrive(b"!foo!bar"))

    def test_split_drive_alt_sep(self):
        self.assertEqual(("c:", "^foo^bar"), self.filesystem.splitdrive("c:^foo^bar"))
        self.assertEqual(("", "foo^bar"), self.filesystem.splitdrive("foo^bar"))
        self.assertEqual(("", "foo^bar!baz"), self.filesystem.splitdrive("foo^bar!baz"))
        self.assertEqual(
            (b"c:", b"^foo^bar"), self.filesystem.splitdrive(b"c:^foo^bar")
        )
        self.assertEqual((b"", b"^foo^bar"), self.filesystem.splitdrive(b"^foo^bar"))
        self.assertEqual(
            (b"", b"^foo^bar!baz"), self.filesystem.splitdrive(b"^foo^bar!baz")
        )

    def test_split_drive_with_unc_path(self):
        self.assertEqual(
            ("!!foo!bar", "!baz"), self.filesystem.splitdrive("!!foo!bar!baz")
        )
        self.assertEqual(("", "!!foo"), self.filesystem.splitdrive("!!foo"))
        self.assertEqual(("", "!!foo!!bar"), self.filesystem.splitdrive("!!foo!!bar"))
        self.assertEqual(("!!foo!bar", "!!"), self.filesystem.splitdrive("!!foo!bar!!"))

    def test_split_drive_with_unc_path_alt_sep(self):
        self.assertEqual(
            ("^^foo^bar", "!baz"), self.filesystem.splitdrive("^^foo^bar!baz")
        )
        self.assertEqual(("", "^^foo"), self.filesystem.splitdrive("^^foo"))
        self.assertEqual(("", "^^foo^^bar"), self.filesystem.splitdrive("^^foo^^bar"))
        self.assertEqual(("^^foo^bar", "^^"), self.filesystem.splitdrive("^^foo^bar^^"))

    def test_split_path_with_drive(self):
        self.assertEqual(("d:!foo", "baz"), self.filesystem.splitpath("d:!foo!baz"))
        self.assertEqual(("d:!foo!baz", ""), self.filesystem.splitpath("d:!foo!baz!"))
        self.assertEqual(("c:", ""), self.filesystem.splitpath("c:"))
        self.assertEqual(("c:!", ""), self.filesystem.splitpath("c:!"))
        self.assertEqual(("c:!!", ""), self.filesystem.splitpath("c:!!"))

    def test_split_path_with_drive_alt_sep(self):
        self.assertEqual(("d:^foo", "baz"), self.filesystem.splitpath("d:^foo^baz"))
        self.assertEqual(("d:^foo^baz", ""), self.filesystem.splitpath("d:^foo^baz^"))
        self.assertEqual(("c:", ""), self.filesystem.splitpath("c:"))
        self.assertEqual(("c:^", ""), self.filesystem.splitpath("c:^"))
        self.assertEqual(("c:^^", ""), self.filesystem.splitpath("c:^^"))

    def test_split_path_with_unc_path(self):
        self.assertEqual(
            ("!!foo!bar!", "baz"), self.filesystem.splitpath("!!foo!bar!baz")
        )
        self.assertEqual(("!!foo!bar", ""), self.filesystem.splitpath("!!foo!bar"))
        self.assertEqual(("!!foo!bar!!", ""), self.filesystem.splitpath("!!foo!bar!!"))

    def test_split_path_with_unc_path_alt_sep(self):
        self.assertEqual(
            ("^^foo^bar^", "baz"), self.filesystem.splitpath("^^foo^bar^baz")
        )
        self.assertEqual(("^^foo^bar", ""), self.filesystem.splitpath("^^foo^bar"))
        self.assertEqual(("^^foo^bar^^", ""), self.filesystem.splitpath("^^foo^bar^^"))

    def test_splitroot_with_drive(self):
        self.assertEqual(
            ("E:", "!", "foo!bar"), self.filesystem.splitroot("E:!foo!bar")
        )
        self.assertEqual(
            ("E:", "!", "!foo!!!bar"), self.filesystem.splitroot("E:!!foo!!!bar")
        )
        self.assertEqual(
            (b"E:", b"!", b"!foo!!!bar"), self.filesystem.splitroot(b"E:!!foo!!!bar")
        )
        self.assertEqual(
            ("C:", "^", "foo^bar"), self.filesystem.splitroot("C:^foo^bar")
        )

    def test_splitroot_with_unc_path(self):
        self.assertEqual(
            ("!!foo!bar", "!", "baz"), self.filesystem.splitroot("!!foo!bar!baz")
        )
        self.assertEqual(
            ("!!?!UNC", "!", "foo!bar"), self.filesystem.splitroot("!!?!UNC!foo!bar")
        )
        self.assertEqual(
            ("^^foo^bar", "^", "baz"), self.filesystem.splitroot("^^foo^bar^baz")
        )
        self.assertEqual(
            (b"!!foo!bar", b"!", b"baz"), self.filesystem.splitroot(b"!!foo!bar!baz")
        )

    def test_splitroot_with_empty_parts(self):
        self.assertEqual(("", "", ""), self.filesystem.splitroot(""))
        self.assertEqual(("", "!", "foo"), self.filesystem.splitroot("!foo"))
        self.assertEqual(("!!foo!bar", "", ""), self.filesystem.splitroot("!!foo!bar"))
        self.assertEqual(("!!foo", "", ""), self.filesystem.splitroot("!!foo"))
        self.assertEqual(
            ("!!foo!bar", "!", ""), self.filesystem.splitroot("!!foo!bar!")
        )
        self.assertEqual(("C:", "", "foo!bar"), self.filesystem.splitroot("C:foo!bar"))


class DiskSpaceTest(TestCase):
    def setUp(self):
        self.fs = fake_filesystem.FakeFilesystem(path_separator="!", total_size=100)
        self.os = fake_os.FakeOsModule(self.fs)
        self.open = fake_open.FakeFileOpen(self.fs)

    def test_disk_usage_on_file_creation(self):
        total_size = 100
        self.fs.add_mount_point("!mount", total_size)

        def create_too_large_file():
            with self.open("!mount!file", "w") as dest:
                dest.write("a" * (total_size + 1))

        with self.assertRaises(OSError):
            create_too_large_file()

        self.assertEqual(0, self.fs.get_disk_usage("!mount").used)

        with self.open("!mount!file", "w") as dest:
            dest.write("a" * total_size)

        self.assertEqual(total_size, self.fs.get_disk_usage("!mount").used)

    def test_disk_usage_on_automounted_drive(self):
        self.fs.is_windows_fs = True
        self.fs.reset(total_size=100)
        self.fs.create_file("!foo!bar", st_size=50)
        self.assertEqual(0, self.fs.get_disk_usage("D:!").used)
        self.fs.cwd = "E:!foo"
        self.assertEqual(0, self.fs.get_disk_usage("!foo").used)

    def test_disk_usage_on_mounted_paths(self):
        self.fs.add_mount_point("!foo", total_size=200)
        self.fs.add_mount_point("!foo!bar", total_size=400)
        self.fs.create_file("!baz", st_size=50)
        self.fs.create_file("!foo!baz", st_size=60)
        self.fs.create_file("!foo!bar!baz", st_size=100)
        self.assertEqual(50, self.fs.get_disk_usage("!").used)
        self.assertEqual(60, self.fs.get_disk_usage("!foo").used)
        self.assertEqual(100, self.fs.get_disk_usage("!foo!bar").used)
        self.assertEqual(400, self.fs.get_disk_usage("!foo!bar").total)

    def test_file_system_size_after_large_file_creation(self):
        filesystem = fake_filesystem.FakeFilesystem(
            path_separator="!", total_size=1024 * 1024 * 1024 * 100
        )
        filesystem.create_file("!foo!baz", st_size=1024 * 1024 * 1024 * 10)
        self.assertEqual(
            (
                1024 * 1024 * 1024 * 100,
                1024 * 1024 * 1024 * 10,
                1024 * 1024 * 1024 * 90,
            ),
            filesystem.get_disk_usage(),
        )

    def test_file_system_size_after_binary_file_creation(self):
        self.fs.create_file("!foo!bar", contents=b"xyzzy")
        self.assertEqual((100, 5, 95), self.fs.get_disk_usage())

    def test_file_system_size_after_ascii_string_file_creation(self):
        self.fs.create_file("!foo!bar", contents="complicated")
        self.assertEqual((100, 11, 89), self.fs.get_disk_usage())

    def test_filesystem_size_after_2byte_unicode_file_creation(self):
        self.fs.create_file("!foo!bar", contents="сложно", encoding="utf-8")
        self.assertEqual((100, 12, 88), self.fs.get_disk_usage())

    def test_filesystem_size_after_3byte_unicode_file_creation(self):
        self.fs.create_file("!foo!bar", contents="複雑", encoding="utf-8")
        self.assertEqual((100, 6, 94), self.fs.get_disk_usage())

    def test_file_system_size_after_file_deletion(self):
        self.fs.create_file("!foo!bar", contents=b"xyzzy")
        self.fs.create_file("!foo!baz", st_size=20)
        self.fs.remove_object("!foo!bar")
        self.assertEqual((100, 20, 80), self.fs.get_disk_usage())

    def test_file_system_size_after_directory_removal(self):
        self.fs.create_file("!foo!bar", st_size=10)
        self.fs.create_file("!foo!baz", st_size=20)
        self.fs.create_file("!foo1!bar", st_size=40)
        self.fs.remove_object("!foo")
        self.assertEqual((100, 40, 60), self.fs.get_disk_usage())

    def test_creating_file_with_fitting_content(self):
        initial_usage = self.fs.get_disk_usage()

        try:
            self.fs.create_file("!foo!bar", contents=b"a" * 100)
        except OSError:
            self.fail(
                "File with contents fitting into disk space " "could not be written."
            )

        self.assertEqual(initial_usage.used + 100, self.fs.get_disk_usage().used)

    def test_creating_file_with_content_too_large(self):
        def create_large_file():
            self.fs.create_file("!foo!bar", contents=b"a" * 101)

        initial_usage = self.fs.get_disk_usage()

        with self.assertRaises(OSError):
            create_large_file()

        self.assertEqual(initial_usage, self.fs.get_disk_usage())

    def test_creating_file_with_fitting_size(self):
        initial_usage = self.fs.get_disk_usage()

        try:
            self.fs.create_file("!foo!bar", st_size=100)
        except OSError:
            self.fail("File with size fitting into disk space could not be written.")

        self.assertEqual(initial_usage.used + 100, self.fs.get_disk_usage().used)

    def test_creating_file_with_size_too_large(self):
        initial_usage = self.fs.get_disk_usage()

        def create_large_file():
            self.fs.create_file("!foo!bar", st_size=101)

        with self.assertRaises(OSError):
            create_large_file()

        self.assertEqual(initial_usage, self.fs.get_disk_usage())

    def test_resize_file_with_fitting_size(self):
        file_object = self.fs.create_file("!foo!bar", st_size=50)
        try:
            file_object.set_large_file_size(100)
            file_object.set_contents(b"a" * 100)
        except OSError:
            self.fail("Resizing file failed although disk space was sufficient.")

    def test_resize_file_with_size_too_large(self):
        file_object = self.fs.create_file("!foo!bar", st_size=50)
        with self.raises_os_error(errno.ENOSPC):
            file_object.set_large_file_size(200)
        with self.raises_os_error(errno.ENOSPC):
            file_object.set_contents("a" * 150)

    def test_file_system_size_after_directory_rename(self):
        self.fs.create_file("!foo!bar", st_size=20)
        self.os.rename("!foo", "!baz")
        self.assertEqual(20, self.fs.get_disk_usage().used)

    def test_file_system_size_after_file_rename(self):
        self.fs.create_file("!foo!bar", st_size=20)
        self.os.rename("!foo!bar", "!foo!baz")
        self.assertEqual(20, self.fs.get_disk_usage().used)

    def test_that_hard_link_does_not_change_used_size(self):
        file1_path = "test_file1"
        file2_path = "test_file2"
        self.fs.create_file(file1_path, st_size=20)
        self.assertEqual(20, self.fs.get_disk_usage().used)
        # creating a hard link shall not increase used space
        self.os.link(file1_path, file2_path)
        self.assertEqual(20, self.fs.get_disk_usage().used)
        # removing a file shall not decrease used space
        # if a hard link still exists
        self.os.unlink(file1_path)
        self.assertEqual(20, self.fs.get_disk_usage().used)
        self.os.unlink(file2_path)
        self.assertEqual(0, self.fs.get_disk_usage().used)

    def test_that_the_size_of_correct_mount_point_is_used(self):
        self.fs.add_mount_point("!mount_limited", total_size=50)
        self.fs.add_mount_point("!mount_unlimited")

        with self.raises_os_error(errno.ENOSPC):
            self.fs.create_file("!mount_limited!foo", st_size=60)
        with self.raises_os_error(errno.ENOSPC):
            self.fs.create_file("!bar", st_size=110)

        try:
            self.fs.create_file("!foo", st_size=60)
            self.fs.create_file("!mount_limited!foo", st_size=40)
            self.fs.create_file("!mount_unlimited!foo", st_size=1000000)
        except OSError:
            self.fail(
                "File with contents fitting into " "disk space could not be written."
            )

    def test_that_disk_usage_of_correct_mount_point_is_used(self):
        self.fs.add_mount_point("!mount1", total_size=20)
        self.fs.add_mount_point("!mount1!bar!mount2", total_size=50)

        self.fs.create_file("!foo!bar", st_size=10)
        self.fs.create_file("!mount1!foo!bar", st_size=10)
        self.fs.create_file("!mount1!bar!mount2!foo!bar", st_size=10)

        self.assertEqual(90, self.fs.get_disk_usage("!foo").free)
        self.assertEqual(10, self.fs.get_disk_usage("!mount1!foo").free)
        self.assertEqual(40, self.fs.get_disk_usage("!mount1!bar!mount2").free)

    def test_set_larger_disk_size(self):
        self.fs.add_mount_point("!mount1", total_size=20)
        with self.raises_os_error(errno.ENOSPC):
            self.fs.create_file("!mount1!foo", st_size=100)
        self.fs.set_disk_usage(total_size=200, path="!mount1")
        self.fs.create_file("!mount1!foo", st_size=100)
        self.assertEqual(100, self.fs.get_disk_usage("!mount1!foo").free)

    def test_set_smaller_disk_size(self):
        self.fs.add_mount_point("!mount1", total_size=200)
        self.fs.create_file("!mount1!foo", st_size=100)
        with self.raises_os_error(errno.ENOSPC):
            self.fs.set_disk_usage(total_size=50, path="!mount1")
        self.fs.set_disk_usage(total_size=150, path="!mount1")
        self.assertEqual(50, self.fs.get_disk_usage("!mount1!foo").free)

    def test_disk_size_on_unlimited_disk(self):
        self.fs.add_mount_point("!mount1")
        self.fs.create_file("!mount1!foo", st_size=100)
        self.fs.set_disk_usage(total_size=1000, path="!mount1")
        self.assertEqual(900, self.fs.get_disk_usage("!mount1!foo").free)

    def test_disk_size_on_auto_mounted_drive_on_file_creation(self):
        self.fs.is_windows_fs = True
        # drive d: shall be auto-mounted and the used size adapted
        self.fs.create_file("d:!foo!bar", st_size=100)
        self.fs.set_disk_usage(total_size=1000, path="d:")
        self.assertEqual(self.fs.get_disk_usage("d:!foo").free, 900)

    def test_disk_size_on_auto_mounted_drive_on_directory_creation(self):
        self.fs.is_windows_fs = True
        self.fs.create_dir("d:!foo!bar")
        self.fs.create_file("d:!foo!bar!baz", st_size=100)
        self.fs.create_file("d:!foo!baz", st_size=100)
        self.fs.set_disk_usage(total_size=1000, path="d:")
        self.assertEqual(800, self.fs.get_disk_usage("d:!foo").free)

    def test_copying_preserves_byte_contents(self):
        source_file = self.fs.create_file("foo", contents=b"somebytes")
        dest_file = self.fs.create_file("bar")
        dest_file.set_contents(source_file.contents)
        self.assertEqual(dest_file.contents, source_file.contents)

    def test_diskusage_after_open_write(self):
        with self.open("bar.txt", "w") as f:
            f.write("a" * 60)
            f.flush()
        self.assertEqual(60, self.fs.get_disk_usage()[1])

    def test_disk_full_after_reopened(self):
        with self.open("bar.txt", "w") as f:
            f.write("a" * 60)
        with self.open("bar.txt") as f:
            self.assertEqual("a" * 60, f.read())
        with self.raises_os_error(errno.ENOSPC):
            with self.open("bar.txt", "w") as f:
                f.write("b" * 110)
                with self.raises_os_error(errno.ENOSPC):
                    f.flush()
        with self.open("bar.txt") as f:
            self.assertEqual("", f.read())

    def test_disk_full_append(self):
        file_path = "bar.txt"
        with self.open(file_path, "w") as f:
            f.write("a" * 60)
        with self.open(file_path) as f:
            self.assertEqual("a" * 60, f.read())
        with self.raises_os_error(errno.ENOSPC):
            with self.open(file_path, "a") as f:
                f.write("b" * 41)
                with self.raises_os_error(errno.ENOSPC):
                    f.flush()
        with self.open("bar.txt") as f:
            self.assertEqual(f.read(), "a" * 60)

    def test_disk_full_after_reopened_rplus_seek(self):
        with self.open("bar.txt", "w") as f:
            f.write("a" * 60)
        with self.open("bar.txt") as f:
            self.assertEqual(f.read(), "a" * 60)
        with self.raises_os_error(errno.ENOSPC):
            with self.open("bar.txt", "r+") as f:
                f.seek(50)
                f.write("b" * 60)
                with self.raises_os_error(errno.ENOSPC):
                    f.flush()
        with self.open("bar.txt") as f:
            self.assertEqual(f.read(), "a" * 60)


class MountPointTest(TestCase):
    def setUp(self):
        self.filesystem = fake_filesystem.FakeFilesystem(
            path_separator="!", total_size=100
        )

    def add_mount_points(self):
        self.filesystem.add_mount_point("!foo")
        self.filesystem.add_mount_point("!bar")
        self.filesystem.add_mount_point("!foo!baz")

    def test_that_new_mount_points_get_new_device_number(self):
        self.add_mount_points()
        self.assertEqual(1, self.filesystem.get_object("!").st_dev)
        self.assertEqual(2, self.filesystem.get_object("!foo").st_dev)
        self.assertEqual(3, self.filesystem.get_object("!bar").st_dev)
        self.assertEqual(4, self.filesystem.get_object("!foo!baz").st_dev)

    def test_that_new_directories_get_correct_device_number(self):
        self.add_mount_points()
        self.assertEqual(1, self.filesystem.create_dir("!foo1!bar").st_dev)
        self.assertEqual(2, self.filesystem.create_dir("!foo!bar").st_dev)
        self.assertEqual(4, self.filesystem.create_dir("!foo!baz!foo!bar").st_dev)

    def test_that_new_files_get_correct_device_number(self):
        self.add_mount_points()
        self.assertEqual(1, self.filesystem.create_file("!foo1!bar").st_dev)
        self.assertEqual(2, self.filesystem.create_file("!foo!bar").st_dev)
        self.assertEqual(4, self.filesystem.create_file("!foo!baz!foo!bar").st_dev)

    def test_that_mount_point_cannot_be_added_twice(self):
        self.add_mount_points()
        with self.raises_os_error(errno.EEXIST):
            self.filesystem.add_mount_point("!foo")
        with self.raises_os_error(errno.EEXIST):
            self.filesystem.add_mount_point("!foo!")

    def test_that_drives_are_auto_mounted(self):
        self.filesystem.is_windows_fs = True
        self.add_mount_points()
        self.filesystem.create_dir("d:!foo!bar")
        self.filesystem.create_file("d:!foo!baz")
        self.filesystem.create_file("z:!foo!baz")
        self.assertEqual(5, self.filesystem.get_object("d:").st_dev)
        self.assertEqual(5, self.filesystem.get_object("d:!foo!bar").st_dev)
        self.assertEqual(5, self.filesystem.get_object("d:!foo!baz").st_dev)
        self.assertEqual(6, self.filesystem.get_object("z:!foo!baz").st_dev)

    def test_that_drives_are_auto_mounted_case_insensitive(self):
        self.filesystem.is_windows_fs = True
        self.add_mount_points()
        self.filesystem.is_case_sensitive = False
        self.filesystem.create_dir("D:!foo!bar")
        self.filesystem.create_file("e:!foo!baz")
        self.assertEqual(5, self.filesystem.get_object("D:").st_dev)
        self.assertEqual(5, self.filesystem.get_object("d:!foo!bar").st_dev)
        self.assertEqual(6, self.filesystem.get_object("e:!foo").st_dev)
        self.assertEqual(6, self.filesystem.get_object("E:!Foo!Baz").st_dev)

    def test_that_unc_paths_are_auto_mounted(self):
        self.filesystem.is_windows_fs = True
        self.add_mount_points()
        self.filesystem.create_dir("!!foo!bar!baz")
        self.filesystem.create_file("!!foo!bar!bip!bop")
        self.assertEqual(5, self.filesystem.get_object("!!foo!bar").st_dev)
        self.assertEqual(5, self.filesystem.get_object("!!foo!bar!bip!bop").st_dev)


class ConvenienceMethodTest(RealFsTestCase):
    def test_create_link_with_non_existent_parent(self):
        self.skip_if_symlink_not_supported()
        file1_path = self.make_path("test_file1")
        link_path = self.make_path("nonexistent", "test_file2")

        self.filesystem.create_file(file1_path, contents="link test")
        self.assertEqual(self.os.stat(file1_path).st_nlink, 1)
        self.filesystem.create_link(file1_path, link_path)
        self.assertEqual(self.os.stat(file1_path).st_nlink, 2)
        self.assertTrue(self.filesystem.exists(link_path))

    def test_create_symlink_with_non_existent_parent(self):
        self.skip_if_symlink_not_supported()
        file1_path = self.make_path("test_file1")
        link_path = self.make_path("nonexistent", "test_file2")

        self.filesystem.create_file(file1_path, contents="symlink test")
        self.filesystem.create_symlink(link_path, file1_path)
        self.assertTrue(self.filesystem.exists(link_path))
        self.assertTrue(self.filesystem.islink(link_path))


class RealFileSystemAccessTest(RealFsTestCase):
    def setUp(self):
        # use the real path separator to work with the real file system
        self.filesystem = fake_filesystem.FakeFilesystem()
        self.fake_open = fake_filesystem.FakeFileOpen(self.filesystem)
        self.pyfakefs_path = os.path.split(os.path.dirname(os.path.abspath(__file__)))[
            0
        ]
        self.root_path = os.path.split(self.pyfakefs_path)[0]

    def test_add_non_existing_real_file_raises(self):
        nonexisting_path = os.path.join("nonexisting", "test.txt")
        with self.assertRaises(OSError):
            self.filesystem.add_real_file(nonexisting_path)
        self.assertFalse(self.filesystem.exists(nonexisting_path))

    def test_add_non_existing_real_directory_raises(self):
        nonexisting_path = "/nonexisting"
        with self.raises_os_error(errno.ENOENT):
            self.filesystem.add_real_directory(nonexisting_path)
        self.assertFalse(self.filesystem.exists(nonexisting_path))

    def test_existing_fake_file_raises(self):
        real_file_path = __file__
        self.filesystem.create_file(real_file_path)
        with self.raises_os_error(errno.EEXIST):
            self.filesystem.add_real_file(real_file_path)

    def test_existing_fake_directory_raises(self):
        self.filesystem.create_dir(self.root_path)
        with self.raises_os_error(errno.EEXIST):
            self.filesystem.add_real_directory(self.root_path)

    def check_fake_file_stat(self, fake_file, real_file_path, target_path=None):
        if target_path is None or target_path == real_file_path:
            self.assertTrue(self.filesystem.exists(real_file_path))
        else:
            self.assertFalse(self.filesystem.exists(real_file_path))
            self.assertTrue(self.filesystem.exists(target_path))

        real_stat = os.stat(real_file_path)
        self.assertIsNone(fake_file._byte_contents)
        self.assertEqual(fake_file.st_size, real_stat.st_size)
        self.assertAlmostEqual(fake_file.st_ctime, real_stat.st_ctime, places=5)
        self.assertAlmostEqual(fake_file.st_atime, real_stat.st_atime, places=5)
        self.assertAlmostEqual(fake_file.st_mtime, real_stat.st_mtime, places=5)
        self.assertEqual(fake_file.st_uid, real_stat.st_uid)
        self.assertEqual(fake_file.st_gid, real_stat.st_gid)

    def check_read_only_file(self, fake_file, real_file_path):
        with open(real_file_path, "rb") as f:
            real_contents = f.read()
        self.assertEqual(fake_file.byte_contents, real_contents)
        if not is_root():
            with self.raises_os_error(errno.EACCES):
                self.fake_open(real_file_path, "w")
        else:
            with self.fake_open(real_file_path, "w"):
                pass

    def check_writable_file(self, fake_file, real_file_path):
        with open(real_file_path, "rb") as f:
            real_contents = f.read()
        self.assertEqual(fake_file.byte_contents, real_contents)
        with self.fake_open(real_file_path, "wb") as f:
            f.write(b"test")
        with open(real_file_path, "rb") as f:
            real_contents1 = f.read()
        self.assertEqual(real_contents1, real_contents)
        with self.fake_open(real_file_path, "rb") as f:
            fake_contents = f.read()
        self.assertEqual(fake_contents, b"test")

    def test_add_existing_real_file_read_only(self):
        real_file_path = os.path.abspath(__file__)
        fake_file = self.filesystem.add_real_file(real_file_path)
        self.check_fake_file_stat(fake_file, real_file_path)
        self.assertEqual(fake_file.st_mode & 0o333, 0)
        self.check_read_only_file(fake_file, real_file_path)

    def test_add_existing_real_file_read_write(self):
        real_file_path = os.path.realpath(__file__)
        fake_file = self.filesystem.add_real_file(real_file_path, read_only=False)

        self.check_fake_file_stat(fake_file, real_file_path)
        self.assertEqual(fake_file.st_mode, os.stat(real_file_path).st_mode)
        self.check_writable_file(fake_file, real_file_path)

    def test_add_real_file_to_existing_path(self):
        real_file_path = os.path.abspath(__file__)
        self.filesystem.create_file("/foo/bar")
        with self.raises_os_error(errno.EEXIST):
            self.filesystem.add_real_file(real_file_path, target_path="/foo/bar")

    def test_add_real_file_to_non_existing_path(self):
        real_file_path = os.path.abspath(__file__)
        fake_file = self.filesystem.add_real_file(
            real_file_path, target_path="/foo/bar"
        )
        self.check_fake_file_stat(fake_file, real_file_path, target_path="/foo/bar")

    def test_write_to_real_file(self):
        # regression test for #470
        real_file_path = os.path.abspath(__file__)
        self.filesystem.add_real_file(real_file_path, read_only=False)
        with self.fake_open(real_file_path, "w") as f:
            f.write("foo")

        with self.fake_open(real_file_path, "rb") as f:
            self.assertEqual(b"foo", f.read())

    def test_add_existing_real_directory_read_only(self):
        self.filesystem.add_real_directory(self.pyfakefs_path)
        self.assertTrue(self.filesystem.exists(self.pyfakefs_path))
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(self.pyfakefs_path, "fake_filesystem.py")
            )
        )
        self.assertTrue(
            self.filesystem.exists(os.path.join(self.pyfakefs_path, "fake_pathlib.py"))
        )

        file_path = os.path.join(self.pyfakefs_path, "fake_filesystem_shutil.py")
        fake_file = self.filesystem.resolve(file_path)
        self.check_fake_file_stat(fake_file, file_path)
        self.check_read_only_file(fake_file, file_path)

    def test_add_existing_real_directory_tree(self):
        self.filesystem.add_real_directory(self.root_path)
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(
                    self.root_path,
                    "pyfakefs",
                    "tests",
                    "fake_filesystem_test.py",
                )
            )
        )
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(self.root_path, "pyfakefs", "fake_filesystem.py")
            )
        )
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(self.root_path, "pyfakefs", "__init__.py")
            )
        )

    @contextlib.contextmanager
    def create_symlinks(self, symlinks):
        for link in symlinks:
            os.symlink(link[0], link[1])

        yield

        for link in symlinks:
            os.unlink(link[1])

    def test_add_existing_real_directory_symlink(self):
        fake_open = fake_filesystem.FakeFileOpen(self.filesystem)
        real_directory = os.path.join(self.root_path, "pyfakefs", "tests")
        symlinks = [
            (
                "..",
                os.path.join(real_directory, "fixtures", "symlink_dir_relative"),
            ),
            (
                "../all_tests.py",
                os.path.join(real_directory, "fixtures", "symlink_file_relative"),
            ),
            (
                real_directory,
                os.path.join(real_directory, "fixtures", "symlink_dir_absolute"),
            ),
            (
                os.path.join(real_directory, "all_tests.py"),
                os.path.join(real_directory, "fixtures", "symlink_file_absolute"),
            ),
            (
                "/etc/something",
                os.path.join(
                    real_directory, "fixtures", "symlink_file_absolute_outside"
                ),
            ),
        ]

        self.filesystem.create_file("/etc/something")

        with fake_open("/etc/something", "w") as f:
            f.write("good morning")

        try:
            with self.create_symlinks(symlinks):
                self.filesystem.add_real_directory(real_directory, lazy_read=False)
        except OSError:
            if self.is_windows:
                raise unittest.SkipTest("Symlinks under Windows need admin privileges")
            raise

        for link in symlinks:
            self.assertTrue(self.filesystem.islink(link[1]))

        # relative
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(
                    self.root_path,
                    "pyfakefs",
                    "tests",
                    "fixtures/symlink_dir_relative",
                )
            )
        )
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(
                    self.root_path,
                    "pyfakefs",
                    "tests",
                    "fixtures/symlink_dir_relative/all_tests.py",
                )
            )
        )
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(
                    self.root_path,
                    "pyfakefs",
                    "tests",
                    "fixtures/symlink_file_relative",
                )
            )
        )

        # absolute
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(
                    self.root_path,
                    "pyfakefs",
                    "tests",
                    "fixtures/symlink_dir_absolute",
                )
            )
        )
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(
                    self.root_path,
                    "pyfakefs",
                    "tests",
                    "fixtures/symlink_dir_absolute/all_tests.py",
                )
            )
        )
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(
                    self.root_path,
                    "pyfakefs",
                    "tests",
                    "fixtures/symlink_file_absolute",
                )
            )
        )

        # outside
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(
                    self.root_path,
                    "pyfakefs",
                    "tests",
                    "fixtures/symlink_file_absolute_outside",
                )
            )
        )
        self.assertEqual(
            fake_open(
                os.path.join(
                    self.root_path,
                    "pyfakefs",
                    "tests",
                    "fixtures/symlink_file_absolute_outside",
                )
            ).read(),
            "good morning",
        )

    def test_add_existing_real_directory_symlink_target_path(self):
        self.skip_if_symlink_not_supported(force_real_fs=True)
        real_directory = os.path.join(self.root_path, "pyfakefs", "tests")
        symlinks = [
            (
                "..",
                os.path.join(real_directory, "fixtures", "symlink_dir_relative"),
            ),
            (
                "../all_tests.py",
                os.path.join(real_directory, "fixtures", "symlink_file_relative"),
            ),
        ]

        with self.create_symlinks(symlinks):
            self.filesystem.add_real_directory(
                real_directory, target_path="/path", lazy_read=False
            )

        self.assertTrue(self.filesystem.exists("/path/fixtures/symlink_dir_relative"))
        self.assertTrue(
            self.filesystem.exists("/path/fixtures/symlink_dir_relative/all_tests.py")
        )
        self.assertTrue(self.filesystem.exists("/path/fixtures/symlink_file_relative"))

    def test_add_existing_real_directory_symlink_lazy_read(self):
        self.skip_if_symlink_not_supported(force_real_fs=True)
        real_directory = os.path.join(self.root_path, "pyfakefs", "tests")
        symlinks = [
            (
                "..",
                os.path.join(real_directory, "fixtures", "symlink_dir_relative"),
            ),
            (
                "../all_tests.py",
                os.path.join(real_directory, "fixtures", "symlink_file_relative"),
            ),
        ]

        with self.create_symlinks(symlinks):
            self.filesystem.add_real_directory(
                real_directory, target_path="/path", lazy_read=True
            )

            self.assertTrue(
                self.filesystem.exists("/path/fixtures/symlink_dir_relative")
            )
            self.assertTrue(
                self.filesystem.exists(
                    "/path/fixtures/symlink_dir_relative/all_tests.py"
                )
            )
            self.assertTrue(
                self.filesystem.exists("/path/fixtures/symlink_file_relative")
            )

    def test_add_existing_real_directory_tree_to_existing_path(self):
        self.filesystem.create_dir("/foo/bar")
        with self.raises_os_error(errno.EEXIST):
            self.filesystem.add_real_directory(self.root_path, target_path="/foo/bar")

    def test_add_existing_real_directory_tree_to_other_path(self):
        self.filesystem.add_real_directory(self.root_path, target_path="/foo/bar")
        self.assertFalse(
            self.filesystem.exists(
                os.path.join(self.pyfakefs_path, "tests", "fake_filesystem_test.py")
            )
        )
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(
                    "foo",
                    "bar",
                    "pyfakefs",
                    "tests",
                    "fake_filesystem_test.py",
                )
            )
        )
        self.assertFalse(
            self.filesystem.exists(
                os.path.join(self.root_path, "pyfakefs", "fake_filesystem.py")
            )
        )
        self.assertTrue(
            self.filesystem.exists(
                os.path.join("foo", "bar", "pyfakefs", "__init__.py")
            )
        )

    def test_get_object_from_lazily_added_real_directory(self):
        self.filesystem.is_case_sensitive = True
        self.filesystem.add_real_directory(self.root_path)
        self.assertTrue(
            self.filesystem.get_object(
                os.path.join(self.root_path, "pyfakefs", "fake_filesystem.py")
            )
        )
        self.assertTrue(
            self.filesystem.get_object(
                os.path.join(self.root_path, "pyfakefs", "__init__.py")
            )
        )

    def test_add_existing_real_directory_lazily(self):
        disk_size = 1024 * 1024 * 1024
        real_dir_path = os.path.join(self.root_path, "pyfakefs")
        self.filesystem.set_disk_usage(disk_size, real_dir_path)
        self.filesystem.add_real_directory(real_dir_path)

        # the directory contents have not been read, the the disk usage
        # has not changed
        self.assertEqual(disk_size, self.filesystem.get_disk_usage(real_dir_path).free)
        # checking for existence shall read the directory contents
        self.assertTrue(
            self.filesystem.get_object(
                os.path.join(real_dir_path, "fake_filesystem.py")
            )
        )
        # so now the free disk space shall have decreased
        self.assertGreater(
            disk_size, self.filesystem.get_disk_usage(real_dir_path).free
        )

    def test_add_existing_real_directory_not_lazily(self):
        disk_size = 1024 * 1024 * 1024
        self.filesystem.set_disk_usage(disk_size, self.pyfakefs_path)
        self.filesystem.add_real_directory(self.pyfakefs_path, lazy_read=False)

        # the directory has been read, so the file sizes have
        # been subtracted from the free space
        self.assertGreater(
            disk_size, self.filesystem.get_disk_usage(self.pyfakefs_path).free
        )

    def test_add_existing_real_directory_read_write(self):
        self.filesystem.add_real_directory(self.pyfakefs_path, read_only=False)
        self.assertTrue(self.filesystem.exists(self.pyfakefs_path))
        self.assertTrue(
            self.filesystem.exists(
                os.path.join(self.pyfakefs_path, "fake_filesystem.py")
            )
        )
        self.assertTrue(
            self.filesystem.exists(os.path.join(self.pyfakefs_path, "fake_pathlib.py"))
        )

        file_path = os.path.join(self.pyfakefs_path, "pytest_plugin.py")
        fake_file = self.filesystem.resolve(file_path)
        self.check_fake_file_stat(fake_file, file_path)
        self.check_writable_file(fake_file, file_path)

    def test_add_existing_real_paths_read_only(self):
        real_file_path = os.path.realpath(__file__)
        fixture_path = os.path.join(self.pyfakefs_path, "tests", "fixtures")
        self.filesystem.add_real_paths([real_file_path, fixture_path])

        fake_file = self.filesystem.resolve(real_file_path)
        self.check_fake_file_stat(fake_file, real_file_path)
        self.check_read_only_file(fake_file, real_file_path)

        real_file_path = os.path.join(fixture_path, "module_with_attributes.py")
        fake_file = self.filesystem.resolve(real_file_path)
        self.check_fake_file_stat(fake_file, real_file_path)
        self.check_read_only_file(fake_file, real_file_path)

    def test_add_existing_real_paths_read_write(self):
        real_file_path = os.path.realpath(__file__)
        fixture_path = os.path.join(self.pyfakefs_path, "tests", "fixtures")
        self.filesystem.add_real_paths([real_file_path, fixture_path], read_only=False)

        fake_file = self.filesystem.resolve(real_file_path)
        self.check_fake_file_stat(fake_file, real_file_path)
        self.check_writable_file(fake_file, real_file_path)

        real_file_path = os.path.join(fixture_path, "module_with_attributes.py")
        fake_file = self.filesystem.resolve(real_file_path)
        self.check_fake_file_stat(fake_file, real_file_path)
        self.check_writable_file(fake_file, real_file_path)


class FileSideEffectTests(TestCase):
    def side_effect(self):
        test_case = self
        test_case.side_effect_called = False

        def __side_effect(file_object):
            test_case.side_effect_called = True
            test_case.side_effect_file_object_content = file_object.contents

        return __side_effect

    def setUp(self):
        # use the real path separator to work with the real file system
        self.filesystem = fake_filesystem.FakeFilesystem()
        self.filesystem.create_file("/a/b/file_one", side_effect=self.side_effect())

    def test_side_effect_called(self):
        fake_open = fake_filesystem.FakeFileOpen(self.filesystem)
        self.side_effect_called = False
        with fake_open("/a/b/file_one", "w") as handle:
            handle.write("foo")
        self.assertTrue(self.side_effect_called)

    def test_side_effect_file_object(self):
        fake_open = fake_filesystem.FakeFileOpen(self.filesystem)
        self.side_effect_called = False
        with fake_open("/a/b/file_one", "w") as handle:
            handle.write("foo")
        self.assertEqual(self.side_effect_file_object_content, "foo")


if __name__ == "__main__":
    unittest.main()