Mock FS

A configurable mock file system. You know, for testing.

Purpose

Instead of testing against real file system resources, it should be easy to mock up a file system for tests.

Example

The code below creates a mock fs module that is configured to work with a few mock files and directories.

var mock = require('mock-fs');

var fs = mock.fs({
  'path/to/fake/dir': {
    'some-file.txt': 'file content here',
    'empty-dir': {/** empty directory */}
  },
  'path/to/some.png': new Buffer([8, 6, 7, 5, 3, 0, 9]),
  'some/other/path': {/** another empty directory */}
});

If you are testing a module that requires the real fs module, you can use rewire to inject a mock fs module for testing.

var rewire = require("rewire");
var moduleToTest = rewire('./path/to/module');

// inject the mock fs created above
moduleToTest.__set__('fs', fs);

// now functions in moduleToTest will use
// your mock fs instead of the real one

Status

These fs functions are implemented by the built-in binding. They need to be provided by the mock binding.