Barn

Store lazily evaluated blocks for building test fixtures.

Usage

# Define factories with lazily evaluated blocks
Barn.define :post do
  :title => "What's Your Dream Barn Find?",
  :published_at => Time.now
end

# Build instances and override default attributes
Barn.build(:post, :title => "Original Owner Jaguar E-Type For Sale")

# Compose complex objects
Barn.define :comment do
  :post => build(:post),
  :body => "That's a lot of hay for a little pay."
end

Namespacing

When you define factories, they are stored in the global Barn namespace by default. But we do allow you to create your own namespaces.

module Factory
  module Post
    extend Barn::Namespace

    define :draft {...}
    define :published {...}
  end
end

Factory::Post.build(:draft)

Build Chains

A build chain is a list of builders that are called to instantiate an instance. It's the same concept as Rack middleware, but we build object instances instead of HTTP responses. A builder is anything that responds to build and returns a contructed object. An environment hash of available options to passed to build. The default build chain has one builder, [Barn::Builders::HashMerge], that merges attributes into a hash. See [/lib/barn/builders] for more examples.

# Inspect a build chain
Barn.build_chain
=> [Barn::Builders::HashMerge]  # Default is to merge hash attributes

# After building hash attributes, instantiates an ActiveRecord object
Barn.build_chain.unshift Barn::Builders::ActiveRecord

# Instrument the time it takes to run a build chain
Barn.build_chain.unshift Barn::Builders::Instrumentation

Barn.build_chain
=> [Barn::Builders::Instrumentation, Barn::Builders::ActiveRecord, Barn::Builders::HashMerge]

Helpers

Barn provides helpers to let you type less in your tests. Include Barn.helpers to skip typing Barn.build and Barn.define.

# RSpec
RSpec.configure { |c| c.include Barn::Helpers }

describe "Post" do
  it "requires a title" do
    post = build(:post)
  end
end

# ActiveSupport::TestCase
class PostTest < ActiveSupport::TestCase
  include Barn::Helpers

  test "requires a title" do
    post = build(:post)
  end
end

Installation

Add this line to your application's Gemfile:

gem 'barn'

And then execute:

$ bundle

Or install it yourself as:

$ gem install barn

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request