# Machinist 2

*Fixtures aren't fun. Machinist is.*

Machinist 2 is **still in beta**!

If you're using Rails 3, you'll want to give Machinist 2 a go, but be aware
that the documentation is still patchy.

That said, have a look at [the
specs](https://github.com/notahat/machinist/tree/master/spec), starting with
[the spec for
Machinable](https://github.com/notahat/machinist/blob/master/spec/machinable_spec.rb).
No, really, have a look. I wrote this code to be read, and the specs do a
pretty clean job of documenting what it all does.

If, on the other hand, you want the tried, tested, and well-documented official
release version of Machinist, [then go with Machinist
1](http://github.com/notahat/machinist/tree/1.0-maintenance).

- [Home page](http://github.com/notahat/machinist)
- [Google group](http://groups.google.com/group/machinist-users), for support
- [Bug tracker](http://github.com/notahat/machinist/issues), for reporting Machinist bugs


## Introduction

Machinist makes it easy to create objects for use in tests. It generates data
for the attributes you don't care about, and constructs any necessary
associated objects, leaving you to specify only the fields you care about in
your test. For example:

    describe Comment, "without_spam scope" do
      it "doesn't include spam" do
        # This will make a Comment, a Post, and a User (the author of the
        # Post), generate values for all their attributes, and save them:
        spam = Comment.make!(:spam => true)

        Comment.without_spam.should_not include(spam)
      end
    end

You tell Machinist how to do this with blueprints:

    require 'machinist/active_record'

    User.blueprint do
      username { "user#{sn}" }  # Each user gets a unique serial number.
    end

    Post.blueprint do
      author
      title  { "Post #{sn}" }
      body   { "Lorem ipsum..." }
    end

    Comment.blueprint do
      post
      email { "commenter#{sn}@example.com" }
      body  { "Lorem ipsum..." }
    end


## Installation

### Upgrading from Machinist 1

See [the wiki](http://wiki.github.com/notahat/machinist/machinist-2).

### Rails 3

In your app's `Gemfile`, in the `group :test` section, add:

    gem 'machinist', '>= 2.0.0.beta2'

Then run:

    bundle
    rails generate machinist:install

If you want Machinist to automatically add a blueprint to your blueprints file
whenever you generate a model, add the following to your `config/application.rb`
inside the Application class:

    config.generators do |g|
      g.fixture_replacement :machinist
    end

### Rails 2

See [the wiki](http://wiki.github.com/notahat/machinist/rails-2).


## Usage

### Blueprints

A blueprint describes how to generate an object. The blueprint takes care of
providing attributes that your test doesn't care about, leaving you to focus on
just the attributes that are important for the test.
 
A simple blueprint might look like this:
 
    Post.blueprint do
      title  { "A Post" }
      body   { "Lorem ipsum..." }
    end
 
You can then construct a Post from this blueprint with:

    Post.make!
 
When you call `make!`, Machinist calls `Post.new`, then runs through the
attributes in your blueprint, calling the block for each attribute to generate
a value. It then saves and reloads the Post. (It throws an exception if the
Post can't be saved.)

You can override values defined in the blueprint by passing a hash to make:
 
    Post.make!(:title => "A Specific Title")

If you want to generate an object without saving it to the database, replace
`make!` with `make`.


### Unique Attributes

For attributes that need to be unique, you can call the `sn` method from
within the attribute block to get a unique serial number for the object.

    User.blueprint do
      username { "user-#{sn}" }
    end
      

### Associations

If your object needs associated objects, you can generate them like this:

    Comment.blueprint do
      post { Post.make }
    end
 
Calling `Comment.make!` will construct a Comment and its associated Post, and
save both.

Machinist is smart enough to look at the association and work out what sort of
object it needs to create, so you can shorten the above blueprint to:
 
    Comment.blueprint do
      post
    end

If you want to override the value for post when constructing the comment, you
can do this:
 
    post = Post.make(:title => "A particular title)
    comment = Comment.make(:post => post)


For `has_many` and `has_and_belongs_to_many` associations, you can create
multiple associated objects like this:

    Post.blueprint do
      comments(3)  # Makes 3 comments.
    end


### Named Blueprints

Named blueprints let you define variations on an object. For example, suppose
some of your Users are administrators:
 
    User.blueprint do
      name  { "User #{sn}" }
      email { "user-#{sn}@example.com" }
    end
 
    User.blueprint(:admin) do
      name  { "Admin User #{sn}" }
      admin { true }
    end
 
Calling:
 
    User.make!(:admin)
 
will use the `:admin` blueprint.
 
Named blueprints call the default blueprint to set any attributes not
specifically provided, so in this example the `email` attribute will still be
generated even for an admin user.
 
You must define a default blueprint for any class that has a named blueprint,
even if the default blueprint is empty.


### Blueprints on Plain Old Ruby Objects

Machinist also works with plain old Ruby objects. Let's say you have a class like:
 
    class Post
      extend Machinist::Machinable

      attr_accessor :title
      attr_accessor :body
    end

You can blueprint the Post class just like anything else:
 
    Post.blueprint do
      title { "A title!" }
      body  { "A body!" }
    end

And `Post.make` will construct a new Post.


### Other Tricks

You can refer to already assigned attributes when constructing a new attribute:
 
    Post.blueprint do
      author { "Author #{sn}" }
      body   { "Post by #{object.author}" }
    end


## Compatibility

I've tested this with:

Ruby versions: 1.8.7, 1.9.2
Rails versions: 2.3, 3.0

It may well be happy with other versions too, but I'm not promising anything.
Compatibility patches are welcome.


## Developing

The Machinist specs and source code were written to be read, and I'm pretty
happy with them. Don't be afraid to have a look under the hood!

If you want to submit a patch:

- 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.


## Status

In active use in a number of large Rails 2 apps.

Development has been sporadic, but is picking up again.


## Contributors

Machinist is maintained by Pete Yandell ([pete@notahat.com](mailto:pete@notahat.com), [@notahat](http://twitter.com/notahat))

Other contributors include:

[Marcos Arias](http://github.com/yizzreel),
[Jack Dempsey](http://github.com/jackdempsey),
[Jeremy Durham](http://github.com/jeremydurham),
[Clinton Forbes](http://github.com/clinton),
[Perryn Fowler](http://github.com/perryn),
[Niels Ganser](http://github.com/Nielsomat),
[Jeremy Grant](http://github.com/jeremygrant),
[Jon Guymon](http://github.com/gnarg),
[James Healy](http://github.com/yob),
[Ben Hoskings](http://github.com/benhoskings),
[Evan David Light](http://github.com/elight),
[Chris Lloyd](http://github.com/chrislloyd),
[Adam Meehan](http://github.com/adzap),
[Kyle Neath](http://github.com/kneath),
[Lawrence Pit](http://github.com/lawrencepit),
[Xavier Shay](http://github.com/xaviershay),
[T.J. Sheehy](http://github.com/tjsheehy),
[Roland Swingler](http://github.com/knaveofdiamonds),
[Gareth Townsend](http://github.com/quamen),
[Matt Wastrodowski](http://github.com/towski),
[Ian White](http://github.com/ianwhite)

Thanks to Thoughtbot's [Factory
Girl](http://github.com/thoughtbot/factory_girl/tree/master). Machinist was
written because I loved the idea behind Factory Girl, but I thought the
philosophy wasn't quite right, and I hated the syntax.