irb(main):002:0> FileUtils.touch '/foo'
=> ["/foo"]
irb(main):003:0> FakeFS.activate!
=> true
irb(main):004:0> FileUtils.touch '/bar'
Errno::ENOENT: No such file or directory - /bar
        from ./lib/fakefs/fileutils.rb:130:in `touch'
        from ./lib/fakefs/fileutils.rb:124:in `each'
        from ./lib/fakefs/fileutils.rb:124:in `touch'
        from (irb):4