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GivenFilesystem is a set of helpers for testing code which operates on file systems. It lets you create temporary directories and files with given content as test data. You can write to these directories and GivenFilesystem takes care of cleaning up after the test. It only assumes that you can set the path to your file system data in your tests.

GivenFilesystem provides helpers for RSpec and a standalone class.

Usage with RSpec


To use the GivenFilesystem helpers in a RSpec test you have to include the GivenFileSystemSpecHelpers module to get access to the helper methods, and set up the temporary test directory by calling use_given_filesystem:

require "given_filesystem/spec_helpers"

include GivenFilesystemSpecHelpers

describe "some test" do

  it "tests something" do

The activation with use_given_filesystem gives you fine-grained control about in which scope the test directories are created. It takes a parameter to optionally keep the created test files around:

use_given_filesystem( :keep_files => true )

This can be useful when debugging tests.

File fixtures

With GivenFilesystem you can create directories and files with pre-defined content. These can be used as test fixtures for code reading from a file system.

File fixtures, i.e. files containing test content, are stored in the spec/data/ directory. GivenFilesystem provides helper functions to create temporary directories with defined structure and content using the file fixtures. The file names can be taken directly from the name of the file fixtures or be defined when creating the test directory structure.

Creating directories

Create a temporary directory for writing test data:

path = given_directory

Use the returned path to access the directory.

Create an empty temporary directory with a given name for writing test data:

path = given_directory "myname"

Create a temporary directory with a given from data you provide in the directory spec/data of your project:

path = given_directory_from_data "myname"

This copies the directory spec/data/myname to a temporary test directory and returns the path to the myname directory.

You can also create the directory under a different name:

path = given_directory_from_data "myothername", :from => "myname"

This will copy the same data, but put it into a directory named myothername.

Creating files

Create a temporary file with arbitrary content:

path = given_dummy_file

Use the returned path to access the file.

Create a temporary file with given content taken from a file fixture:

path = given_file "myfixture"

The content of the file is taken from a file fixture stored in your spec/data directory. The name of the created file is the same as the name of the file containing the test content.

Create a temporary file with given content under a different name:

path = given_file "myspecialfile", :from => "myfixture"

The content of the file is taken from the file spec/data/myfixture and stored under the name myspecialfile in a temporary directory. You can access it under the returned path.

Creating structures of directories and files

You can combine given_directory and given_file to create file system structures as input for you tests. Here is an example:

path = given_directory "mydir" do
  given_directory "one" do
    given_file "myfile"
    given_file "myotherfile"
  given_directory "two" do
    given_file "myfile2", :from => "myfile"

This will create the following file system structure and return the path to the temporary directory mydir, which you can then use in your tests to access the data:


Using directory structures in name parameters

All directory or file name parameters can contain additional directory structure. The required nested directories are automatically created. For example the call

  given_directory( "a/b/c" )

will create the following structure:


and return the path to the directory a.


You may use GivenFilesystem under the terms of the MIT license.


If you have questions or comments about GivenFilesystem don't hesitate to get in touch with Cornelius Schumacher.


Thanks to David Majda for reviewing code and documentation.