capistrano-spec¶ ↑

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Capistrano… the final frontier of testing… well, maybe not final, but it is a frontier. I had set out to do some bug fixing and some BDDing on some of my capistrano code, but found it wasn’t really obvious how to do so. As a result, I set out to write capistrano-spec and document how to test capistrano libraries.

Install¶ ↑

You know the drill:

gem install capistrano-spec

And require it in your spec/spec_helper.rb:

require 'capistrano-spec'

Designing your capistrano extension¶ ↑

In the wild, you’ll mostly commonly come across two patterns:

• files living under recipes/* that are autoloaded

• files living under lib that are required from config/deploy.rb

In these files, you can start using the capistrano top-level methods, like namespace or task, like:

# in recipes/speak.rb or lib/speak.rb
task :speak do
  set :message, 'oh hai'
  puts message
end

Capistrano does some trickery to require and load so that if you require or load, the file is ran in the context of a Capistrano::Configuration, where all the task and namespace methods you know and love will be available.

Some consider this a little gross, because it’d be easy to accidentally require/load this without being in the context of a Capistrano::Configuration. The answer to this is to pull use Capistrano::Configuration.instance to make sure it’s evaluted in that context:

# in recipes/speak.rb or lib/speak.rb
Capistrano::Configuration.instance(true).load do
  task :speak do
    set :message, 'oh hai'
    puts message
  end
end

There’s a problem though: it’s not particular testable. You can’t take some Capistrano::Configuration and easily bring your task into it.

So, here’s what I recommend instead: create a method for taking a configuration, and adding your goodies to it.

require 'capistrano'
module Capistrano
  module Speak
    def self.load_into(configuration)
      configuration.load do
        task :speak do
          set :message, 'oh hai'
          puts message
        end
      end
    end
  end
end

# may as well load it if we have it
if Capistrano::Configuration.instance
  Capistrano::Speak.load_into(Capistrano::Configuration.instance)
end

Now, we’re going to be able to test this. Behold!

Testing¶ ↑

Alright, we can start testing by making Capistrano::Configuration and load Capistrano::Speak into it.

describe Capistrano::Speak, "loaded into a configuration" do
  before do
    @configuration = Capistrano::Configuration.new
    Capistrano::Speak.load_into(@configuration)
  end

end

Now you have access to a configuration, so you can start poking around the +@configuration+ object as you see fit.

Now, remember, if you set values, you can access them using fetch:

before do
  @configuration.set :foo, 'bar'
end

it "should define foo" do
  @configuration.fetch(:foo).should == 'bar'
end

You can also find and execute tasks, so you can verify if you successfully set a value:

describe 'speak task' do
  before do
    @configuration.find_and_execute_task('speak')
  end

  it "should define message" do
    @configuration.fetch(:message).should == 'oh hai'
  end
end

One thing you might be wondering now is… that’s cool, but what about working with remote servers? I have just the trick for you: extensions to Capistrano::Configuration to track what files were up or downloaded and what commands were run. Now, this is no substitution for manually testing your capistrano recipe by running it on the server, but it is good for sanity checking.

before do
  @configuration = Capistrano::Configuration.new
  @configuration.extend(Capistrano::Spec::ConfigurationExtension)
end

it "should run yes" do
  @configuration.run "yes"
  @configuration.should have_run("yes")
end

it "should upload foo" do
  @configuration.upload 'foo', '/tmp/foo'
  @configuration.should have_uploaded('foo').to('/tmp/foo')
end

it "should have gotten" do
  @configuration.get '/tmp/bar', 'bar'
  @configuration.should have_gotten('/tmp/bar').to('bar')
end

it "should have put" do
  @configuration.put 'some: content', '/config.yml'
  @configuration.should have_put('some: content').to('/config.yml')
end

You also test callbacks to see if your tasks are being called at the right time:

require 'capistrano'
module Capistrano
  module Speak
    def self.load_into(configuration)
      configuration.load do
        before "deploy:finalize_update", "foo:bar"
        namespace :foo do
          task :bar do
            set :message, 'before finalize'
            puts message
          end
        end
      end
    end
  end
end

it "performs foo:bar before deploy:finalize_update" do
  @configuration.should callback('foo:bar').before('deploy:finalize_update')
end

You can also stub requests if you need to access their output:

task :pwd do
  set :pwd, capture('pwd')
end

it 'should capture working directory' do
  @configuration.stub_command 'pwd', data: '/path/to/working/dir'
  @configuration.fetch(:pwd).should == '/path/to/working/dir'
end

Additional options are channel and stream for testing custom run blocks:

task :custom do
  invoke_command 'pwd', :via => :sudo do |ch, stream, data|
    # magical foo
  end
end

As sudo and invoke_command use run internal and capture uses invoke_command they are also stub-able by specifying the exact command.

task :sudo_pwd do
  set :pwd, capture('pwd', :via => :sudo)
end

it 'should capture sudo working directory' do
  @configuration.stub_command 'sudo -p 'sudo password: ' pwd', data: '/sudo/dir'
  @configuration.fetch(:pwd).should == '/sudo/dir'
end

Real world examples¶ ↑

• capistrano-mountaintop

• moonshine

• rvm-capistrano

• capistrano-unicorn

Note on Patches/Pull Requests¶ ↑

• Fork the project.

• Make your feature addition or bug fix.

• Add tests for it. This is important so I don’t break it in a future version unintentionally.

• Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)

• Send me a pull request. Bonus points for topic branches.

Copyright¶ ↑

Copyright © 2010 Joshua Nichols. See LICENSE for details.