os.path and glob Implementations

mockfs: A simple mock filesystem for unit tests.

class mockfs.mfs.Cwd(mfs)
chdir(path)
getcwd()
getcwdu()
class mockfs.mfs.MockFS(entries=None)

MockFS implementation object

Provides stubs for functions in os, os.path, and glob.

abspath(path)
add_entries(entries)

Add new entries to mockfs.

copytree(src, dst)

Copy a directory subtree

Implements the shutil.copytree() interface.

exists(path)

Return True if path exists

Implements the os.path.exists() interface.

getsize(path)

Return the size of a file, reported by os.stat().

glob(pattern)

Implementation of glob.glob()

isdir(path)

Return True if path is a directory

Implements the os.path.isdir() interface.

isfile(path)

Return True if path is a file

Implements the os.path.isfile() interface.

Return True if path is a symlink

Note

Currently hard-wired to return False

listdir(path)

Return the directory contents of ‘path’

Implements the os.listdir() interface. :param path: filesystem path

makedirs(path)

Create directory entries for a path

Raise OSError if the path already exists.

read(path)
remove(path)

Remove the entry for a file path

Implements the os.remove() interface.

rmdir(fspath)

Remove the entry for a directory path

Implements the os.rmdir() interface.

rmtree(path, ignore_errors=False, onerror=None)

Recursively delete a directory tree.

If ignore_errors is set, errors are ignored; otherwise, if onerror is set, it is called to handle the error with arguments (func, path, exc_info) where func is os.listdir, os.remove, or os.rmdir; path is the argument to that function that caused it to fail; and exc_info is a tuple returned by sys.exc_info(). If ignore_errors is false and onerror is None, an exception is raised.

walk(path)

Walk a filesystem path

Implements the os.walk() interface.

class mockfs.mfs.StorageBackend(mfs)
CheckForFile(filename)
DeleteFile(filename)
LoadFile(filename)
SaveFile(filename, data)
mockfs.mfs.replace_builtins(entries=None, context=None)

Replace builtin functions with mockfs.

Parameters:

entries – Dictionary mapping paths to content

Returns:

Newly installed mockfs.mfs.MockFS instance.

>>> import os
>>> import mockfs
>>> fs = mockfs.replace_builtins()
>>> fs.add_entries({
...     '/bin/sh': 'contents',
...     '/bin/ls': 'contents',
... })
>>> assert(os.listdir('/bin') == ['ls', 'sh'])
>>> mockfs.restore_builtins()
mockfs.mfs.restore_builtins()

Restore the original builtin functions.

Utility Functions

mockfs.util.build_nested_dict(entries)

Convert a flat dict of paths to a nested dict

Parameters:

entries (dict) – Path to entry dictionary

e.g. {‘/unix/path’: ‘content’, ‘/unix/dir’: {},}

mockfs.util.build_nested_dir_dict(dirpath)

Build a nested dict of dicts from a directory path

Parameters:

dirpath (str) – Directory path

mockfs.util.is_dir(entry)
mockfs.util.is_file(value)

Is value a file? Equivalent to checking for strings

mockfs.util.is_string(value)

Is value a string?

mockfs.util.merge_dicts(src, dst)

Merge entries from ‘src’ into ‘dst’.

Parameters:

  • src – source dictionary

  • dst – destination dictionary

mockfs.util.sanitize(path)

Clean up path arguments for use with MockFS

MockFS isn’t happy with trailing slashes since it uses a dict to simulate the file system.

File Storage and IO

class mockfs.storage.backend

Example backend.

static CheckForFile(filename)
static DeleteFile(filename)
static LoadFile(filename)
static SaveFile(filename, data)
class mockfs.storage.file(name[, mode])

Open a file. The mode can be ‘r’, ‘w’ or ‘a’ for reading (default), writing or appending. The file will be created if it doesn’t exist when opened for writing or appending; it will be truncated when opened for writing. Add a ‘b’ to the mode for binary files. Add a ‘+’ to the mode to allow simultaneous reading and writing. The preferred way to open a file is with the builtin open() function.

close()

Returns None or (perhaps) an integer. Close the file.

Sets data attribute .closed to True. A closed file cannot be used for further I/O operations. close() may be called more than once without error. Some kinds of file objects (for example, opened by popen()) may return an exit status upon closing.

property closed

True if the file is closed

property encoding

file encoding

property errors

Unicode error handler

fileno()

file descriptor

This is needed for lower-level file interfaces, such os.read().

flush()

Flush the internal I/O buffer.

isatty()

Is the file connected to a tty device? mockfs always returns False.

property mode

file mode, one of r(+)(b), w(+)(b) or a(+)(b)

property name

file name

property newlines

end-of-line convention used in this file

next()

Return the next value, or raise StopIteration.

read(size=DEFAULT)

Read at most size bytes, returned as a string.

If the size argument is negative or omitted, read until EOF is reached. Notice that when in non-blocking mode, less data than what was requested may be returned, even if no size parameter was given.

readline(size=DEFAULT)

Return the next line from the file, as a string.

Retain newline. A non-negative size argument limits the maximum number of bytes to return (an incomplete line may be returned then). Return an empty string at EOF.

readlines(size=DEFAULT)

Return a list of strings, each a line from the file.

Call readline() repeatedly and return a list of the lines so read. The optional size argument, if given, is an approximate bound on the total number of bytes in the lines returned.

seek(position, whence=0)

Move to new file position.

Argument offset is a byte count. Optional argument whence defaults to 0 (offset from start of file, offset should be >= 0); other values are 1 (move relative to current position, positive or negative), and 2 (move relative to end of file, usually negative, although many platforms allow seeking beyond the end of a file). If the file is opened in text mode, only offsets returned by tell() are legal. Use of other offsets causes undefined behavior. Note that not all file objects are seekable.

property softspace

flag indicating that a space needs to be printed; used by print

tell()

Return the current file position, an integer (may be a long integer).

truncate(size=DEFAULT)

Truncate the file to at most size bytes.

Size defaults to the current file position, as returned by tell().

write(data)

Write data to the file.

Note that due to buffering, flush() or close() may be needed before the file on disk reflects the data written.

writelines(sequence)

Write the strings to the file.

Note that newlines are not added. The sequence can be any iterable object producing strings. This is equivalent to calling write() for each string.

xreadlines()

Returns self for backward compatibility.

File objects now include the performance optimizations previously implemented in the xreadlines module.

mockfs.storage.get_new_fileno()
mockfs.storage.open(name, mode='r', encoding=None, errors=None)

Open a file using the file() type, returns a file object.

This is the preferred way to open a file.

mockfs.storage.replace_builtins()

replace file and open in the builtin module

mockfs.storage.restore_builtins()

restore the original file and open to the builtin module