nodule

Warning

Nodule is really new software (all of 2 weeks old). It was extracted from a larger project where it is used for some really large integration tests. We'll remove this message once Nodule has a reasonable set of tests of its own.

Overview

Nodule is an integration test harness that simplifies the setup and teardown of multi-process or large multi-component applications.

When setting up complex tests with multiple processes, a lot of work ends up going into generating configuration, command-line parameters, and other fiddly things that are their own sources of annoying bugs. Nodule tries to tidy some of that up by providing a way to define a test topology that automatically injects data in the right places lazily so it doesn't all have to be done up-front.

Symbols

In as many places as possible, Nodule allows you to use a symbol as a placeholder for a value, which it will automatically resolve when it's needed and no earlier, so you aren't forced to worry about ordering.

Saying ":file => Nodule::Tempfile.new" means that :file will resolve to a temporary file's path (via .to_s) in any place it appears as a placeholder. :file can be used before it's associated with a tempfile.

Procs

In many places, procs can be used as placeholders and will be automatically called when needed.

Arrays

The process module requires commands to be specified as argv-style arrays. The array is scanned for placeholders, which are converted as already described. The one addition is sub-arrays, which are resolved and concatenated without padding. This is useful for parameters that use '=' without spaces, for example, "dd if=" would be specified as ['dd', ['if=', :file]]. These sub-arrays are resolved recursively, so multiple levels are allowed.

Example

#!/usr/bin/env ruby

require "test/unit"
require 'nodule/process'
require 'nodule/topology'
require 'nodule/tempfile'
require 'nodule/console'

class NoduleSimpleTest < Test::Unit::TestCase
  def setup
    @topo = Nodule::Topology.new(
      :greenio => Nodule::Console.new(:fg => :green),
      :redio   => Nodule::Console.new(:fg => :red),
      :file1   => Nodule::Tempfile.new(".html"),
      :wget    => Nodule::Process.new(
        '/usr/bin/wget', '-O', :file1, 'http://www.ooyala.com',
        :stdout => :greenio, :stderr => :redio
      )
    )

    @topo.run_serially
  end

  def teardown
    @topo.cleanup
  end

  def test_heartbeat
    filename = @topo[:file1].to_s
    assert File.exists? filename
  end
end

Authors

• Viet Nguyen
• Noah Gibbs
• Al Tobey
• Jay Bhat

Dependencies

• Ruby 1.9 (tested on 1.9.2p290)
• rainbow
• ffi-rzmq (for Nodule::ZeroMQ, optional)

License

Nodule is released under the MIT license.