Mocking calls to FileUtils or File means tightly coupling tests with the implementation.
it "creates a directory" do FileUtils.expects(:mkdir).with("directory").once Library.add "directory" end
The above test will break if
mkdir_p is used instead.
Refactoring code should not necessitate refactoring tests.
A better approach is to use a temp directory if you are working with relative directories.
require 'tmpdir' it "creates a directory" do Dir.mktmpdir do |dir| Dir.chdir dir do Library.add "directory" assert File.directory?("directory") end end end
But if you are working with absolute directories or do not want to use temporary directories, use FakeFS instead:
it "creates a directory" do FakeFS do Library.add "directory" assert File.directory?("directory") end end
gem install fakefs
To fake out the FS:
Temporarily faking the FS
require 'fakefs/safe' FakeFS.activate! # your code FakeFS.deactivate! # or FakeFS do # your code end
In rails projects, add this to your Gemfile:
gem "fakefs", require: "fakefs/safe"
Include FakeFS::SpecHelpers to turn FakeFS on and off in an example group:
require 'fakefs/spec_helpers' describe "my spec" do include FakeFS::SpecHelpers end
lib/fakefs/spec_helpers.rb for more info.
Integrating with other filesystem libraries
Third-party libraries may add methods to filesystem-related classes. FakeFS
doesn't support these methods out of the box, but you can define fake versions
yourself on the equivalent FakeFS classes. For example,
A fake version can be provided as follows:
FakeFS::File.class_eval do def content_type 'fake/file' end end
MockFS ?How is this different than
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.
As of v0.5.0, FakeFS's current working directory (i.e.
independent of the real working directory. Previously if the real working
directory were, for example,
/Users/donovan/Desktop, then FakeFS would use
that as the fake working directory too, even though it most likely didn't
exist. This caused all kinds of subtle bugs. Now the default working directory
is the only thing that is guaranteed to exist, namely the root (i.e.
may be important when upgrading from v0.4.x to v0.5.x, especially if you depend
on the real working directory while using FakeFS.
Once you've made your great commits:
- Fork FakeFS
- Create a topic branch -
git checkout -b my_branch
- Push to your branch -
git push origin my_branch
- Open a Pull Request
- That's it!
git clone git://github.com/defunkt/fakefs.git
- Home: https://github.com/fakefs/fakefs
- Docs: http://www.rubydoc.info/github/defunkt/fakefs
- Bugs: https://github.com/fakefs/fakefs/issues
- Test: https://travis-ci.org/#!/defunkt/fakefs
- Gems: https://rubygems.org/gems/fakefs
- Update version in lib/fakefs/version.rb
- Commit it
bundle exec rake publish