RSpec-Design-Helper is a gem that enhances RSpec for the simple first steps of BDD.

When the need for a class first appears, you can easily generate failing specs that describe the interface to your class.

implements

Specifies that the subject must implement the specified methods.

Use When: You are designing the class, and you want to ensure that it exposes a field with a method implementation.

class FailingUser
end

class PassingUser
  def name
    'Billy Chatteroonski'
  end
end

describe FailingUser do
  implements :name # One spec fails. A FailingUser.new does not have a :new method
end

describe PassingUser
  implements :name # One spec passes. A PassingUser.new has a :new method.
end

class_implements

Specifies that the described_class must implement the specified methods.

Use When:

class FailingUser
end

class PassingUser
  def species
    Human
  end
end

describe FailingUser do
  class_implements :species # fails one spec.
end

describe PassingUser do
  class_implements :species # passes one spec.
end

Persistent Classes (a.k.a. Models)

is_persistible

Specifies that instances of described_class respond to save, save! and reload

Use When:

persists

Specifies that the subject is able to assign a sample value, save itself, then reload itself.

Use When: