You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: stubba_example_test.rb
    path of file: ./repos/mocha/test/acceptance
    
    the code of the file until where you have to start completion: require File.expand_path('../acceptance_test_helper', __FILE_
    
  def should_stub_instance_method_on_any_instance_of_a_class
    Widget.any_instance.expects(:model).at_least_once.returns('another_model')
    widget1 = Widget.new
    widget2 = Widget.new
    assert_equal 'another_model', widget1.model
    assert_equal 'another_model', widget2.model
  end