Is there something like VCR (http-interaction stubbing/replay) for commandline calls?

Question

I am developing a system that has a lot of commandline interaction. Sometimes even over SSH. Commands can take as long as 30minutes sometimes to finish.

Currently I am stubbing out most of the system calls on the objects doing that system call. E.g:

class BackupBuilderTest < ActiveSupport::TestCase
  test "it calls the backup utility over ssh" do
    BackupBuilder.expects(:system).with("ssh foo@bar backup").returns(true)
    BackupBuilder.perform(:id => @backup.id)
  end
end

BackupBuilder
  def perform
    system("ssh foo@bar backup")
  end
end

However, a command like ssh foo@bar backup can fail on a lot of levels, and will output a lot of data, which I capture and act on. It also takes a long time to run; not a good thing in integration tests and unacceptable in unit-tests. I'd like to run this, whithout having all the actual ssh and backups running.

For HTTP there is VCR, which does nearly exactly what I'd like to do on my CLI-calls. Is there something for this? Or am I missing some pattern or common stubbing-trick that allows me to do this?

Answer 1

Here's an approach someone took using cram:

http://pbrisbin.com/posts/mocking_bash