StubShell

StubShell helps you to test your libraries that interact with the system through the Kernel backquote and system methods.
It does this by providing a DSL to describe the messages that you expect the shell to receive in the order that you expect to receive them. StubShell can be used to stub simple interactions, or ones that cause the system that you're working with to change state.

gem install stub_shell

require 'stub_shell'

RSpec.configure do |config|
  config.include StubShell::TestHelpers
end

StubShell can handle simple cases where you want to stub a system call in Ruby or more complex interactions where commands may change the state and return values of subsequent commands.

You use StubShell simply by describing the commands that you want stubbed out, along with the value that they should return in STDOUT and STDERR, as well as their exit status.

it ... do
  stub_shell do
    command "ls /tmp/foobar" do
      stdout "hey there"
      stderr "some error"
      exitstatus 2
    end
  end
end

By default, StubShell assumes that STDOUT and STDERR are nil, and that the exit status is 0 (success), so you can leave these options out if you want.

You can stub more complex interactions with the shell, including cases where commands that you execute will change the output of subsequent commands.

stub_shell do
  command 'ls /tmp/foobar' do
    stdout 'yes, foobar exists'
  end

  command "rm /tmp/foobar" do
    stub_shell do
      command 'ls /tmp/foobar' do
        stderr 'the file no longer exists'
        exitstatus 2
      end
    end
  end
end

StubShell starts looking for defined commands at the current level of the execution hierarchy, so if you invoke the command to remove /tmp/foobar above, it will always look at the stub_shell context nested below that command for matches to subsequent commands. If no matching commands are found at that level, StubShell searches recursively upwards in the tree for matches until it either finds one or it runs out of options and raises an error indicating that no matches were found.

You can use regular expressions to match commands in StubShell.

stub_shell do
  command /ls \/tmp.*foo/' do
    stdout 'yes, your directory exists'
  end
end

We suggest that you read the acceptance tests included with this library to help understand the way that it works.

Justin Leitgeb (@jsl) and @itsmeduncan.

1. Fork stub_shell
2. Create a topic branch - git checkout -b my_branch
3. Push to your branch - git push origin my_branch
4. Create a Pull Request from your branch

See LICENSE