Class Factory: Factory_girl-like syntax for dynamically creating Ruby classes
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Latest commit b18c0cb Mar 10, 2010 @patshaughnessy First implementation
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Class Factory: Factory_girl syntax for dynamically creating Ruby classes

Class Factory will dynamically create classes using a factories model similar to factory_girl. But instead of passing a block with model attributes into the factory definition, you pass in a migration defining the attributes of the new model class you want to create:

ClassFactory.define :person do |p|
  p.string  :first_name
  p.string  :last_name
  p.integer :age

Now when you need a “Person” model in your tests you create one like this:

ClassFactory :person
=> Person(id: integer, first_name: string, last_name: string, age: integer)

This can be useful if you're writing tests for a gem or plugin and don't want to load the entire Rails environment, or have access to existing models in a target application. By default Class Factory creates ActiveRecord model classes, but using the :super option you can create any sort of Ruby class. Class Factory also makes it easy for each of your tests to use a different variation on a target class. For example, this will delete the Person model we created above, and create a new Person model that belongs to a group:

ClassFactory :person, :class_eval => 'belongs_to :group' do |p|
  p.string  :first_name
  p.string  :middle_name
  p.string  :last_name
  p.string  :group_id
=> Person(id: integer, first_name: string, middle_name: string, last_name: string, group_id: string)

Creating different variations of the same class can be useful if you're writing tests for a generator, plugin or some other code which has different behavior depending on what classes you run it against.


gem install class_factory


Default: create a new ActiveRecord model, along with a corresponding table in your database:

ClassFactory :person

Execute a migration on the new table specified as a block, defining the attributes of the new model class:

ClassFactory :person do |p|
  p.string  :first_name
  p.string  :last_name
  p.integer :age

Create a class with a specified superclass (default is ActiveRecord::Base):

ClassFactory :person_array, :super => Array

If SuperClass is not a subclass of ActiveRecord::Base then Class Factory won't create a table or run a migration. You can use this to create plain Ruby object classes.

Create a class called “DifferentClass” instead of “Person:”

ClassFactory :person, :class => 'DifferentClass'

Run the given code inside the new class using class_eval:

ClassFactory :person, :class_eval => 'has_many :shoes'

Create a table with the given name, instead of a table called “people:”

ClassFactory :person, :class_eval => 'set_table_name :table_name', :table => 'table_name'

If you provide options when the factory is defined they will be applied to each class created with the factory. You can also provide options when you create a class, in which case they will override the factory options.

Detailed examples and more information