Mocha is great. But when your library is all about manipulating the filesystem, you really want to test the behavior and not the implementation.
If you're mocking and stubbing every call to FileUtils or File, you're tightly coupling your tests with the implementation.
def test_creates_directory FileUtils.expects(:mkdir).with("directory").once Library.add "directory" end
The above test will break if we decide to use
mkdir_p in our code. Refactoring
code shouldn't necessitate refactoring tests.
def test_creates_directory Library.add "directory" assert File.directory?("directory") end
require 'fakefs' # That's it.
Don't Fake the FS Immediately
require 'fakefs/safe' FakeFS.activate! # your code FakeFS.deactivate! # or FakeFS do # your code end
The above approach works with RSpec as well. In addition you may include FakeFS::SpecHelpers to turn FakeFS on and off in a given example group:
require 'fakefs/spec_helpers' describe "my spec" do include FakeFS::SpecHelpers end
See lib/fakefs/spec_helpers.rb for more info.
How is this different than MockFS?
FakeFS provides a test suite and works with symlinks. It's also strictly a test-time dependency: your actual library does not need to use or know about FakeFS.
FakeFS internally uses the
FileUtils constants. If you use
these in your app, be certain you're properly requiring them and not counting
on FakeFS' own require.
$ gem install fakefs
$ rip install git://github.com/defunkt/fakefs.git
git clone git://github.com/defunkt/fakefs.git
- Home: http://github.com/defunkt/fakefs
- Docs: http://defunkt.github.com/fakefs
- Bugs: http://github.com/defunkt/fakefs/issues
- List: http://groups.google.com/group/fakefs
- Test: http://runcoderun.com/defunkt/fakefs
- Gems: http://gemcutter.org/gems/fakefs
- Boss: Chris Wanstrath :: http://github.com/defunkt