What is It?

mockfs is a mock file system for PHP that can be used to test file operations without interacting with the real file system. This means there’s no disk operations or cleanup of any kind that is needed. Create the mock file system, throw data in it, and when you’re done the data simply disappears.

And you can use mockfs with any PHP testing framework.

Features

mockfs comes with several useful features to test complex scenarios:

  • Create mock files and folders

  • Context options to test failures in file operations such as fopen() or fread()

  • Configurable file quotas to limit disk space or number of files by user, group, or both

  • Support for multibyte files and filenames

  • Support for multiple partitions

  • Configurable file separator, case sensitivity, and filename character blacklist

  • Supports multiple read/writes to the same file at the same time

  • Includes support for special files such as /dev/null, /dev/random, /dev/zero, and /dev/full

  • Ability to emulate different file system environments

mockfs is quite extensible. If there’s not already an option to perform a certain style of test, you can create a custom “file” to fail or succeed exactly how you want it to. A good example of this are the special files, such as FullContent.

How It Works

Using a custom stream wrapper, mockfs maps file locations to objects stored in memory. These objects act like real files and can be interacted with like any other file.

Limitations

As of this time, mockfs doesn’t have the code to support the following (yet):

  • flock() - Advisory file locking

  • stream_select() - Retrieve the underlaying resource (likely will never support)

  • stream_set_blocking() - Set blocking/non-blocking mode

  • stream_set_timeout() - Set timeout period

  • stream_set_write_buffer() - Sets write file buffering

  • Symlinks (might not support ever)

Additionally, certain functions do not work with custom stream wrappers and thus they do not work with mockfs. These limitations exist at the PHP level and there are no known ways around them. If you need to test code using any of these functions, you will likely need to use real files:

  • tempnam()

  • realpath()

  • link(), linkinfo(), readlink(), symlink()

  • glob()

  • ZipArchive

Installation →