Blueprints - notahat/machinist GitHub Wiki

A blueprint specifies how to construct an object of a class by providing values for its attributes.

Post.blueprint do
  title { "A Post" }
  body  { "Lorem ipsum..." }
end

If you’ve got an attribute that needs to be unique, Machinist gives you a serial number for the object being created that you can insert into the attribute.

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

Learn more about Serial Numbers.

You can access the object being constructed from within your blueprints, so you can construct one attribute from another.

User.blueprint do
  username { "user#{sn}" }
  email    { "#{object.username}@example.com" }
end

Machinist knows about ActiveRecord associations, and will automatically generate associated objects.

Comment.blueprint do
  post # This will look at the post association, and make the right kind of object.
end

For has_many and has_and_belongs_to_many associations, you can create multiple associated objects by passing a number to the attribute.

Post.blueprint do
  comments(3) # This will make 3 Comments.
end

Learn more about Associations.

Machinist knows about object inheritance, and will apply blueprints from parent classes.

ParentClass.blueprint do
  name { "Fred" }
  age  { 97 }
end

ChildClass.blueprint do
  # The blueprint will take the name attribute from ParentClass's blueprint.
  age { 36 }  # This will override the age from ParentClass.
end

Learn more about Inheritance.

You can create different, named blueprints for a class.

Comment.blueprint(:spam) do
  spam { true }
  body { "Send me money!" }
end

Comment.make(:spam)

Learn more about Named Blueprints.