RSpec lazy subject

Question

When testing class methods, I don't need an instance to be created automatically. Is an implicit subject created automatically, or only when referenced?

describe MyClass do

  it 'uses implicit subject' do
    subject.my_method.should be_true
  end

  it 'does not create a subject' do
    MyClass.works?.should be_true
    # subject should not have been created
  end
end

Answer 1

subject appears to be a method which creates the object necessary and returns it. So it would only create a subject object when called.

It's easy enough to test yourself though...

class MyClass
  cattr_accessor :initialized

  def initialize
    MyClass.initialized = true
  end

  def my_method
    true
  end

  def self.works?
    true
  end
end

describe MyClass do
  it 'uses implicit subject' do
    MyClass.initialized = false
    subject.my_method.should be_true
    MyClass.initialized.should == true
  end

  it 'does not create a subject' do
    MyClass.initialized = false
    MyClass.works?.should be_true
    MyClass.initialized.should == false
  end
end

Those specs pass, proving that it's lazy.