api_spec.rb

before(:each) do
 @user = mock_model(User).as_null_object
end

let(:inventory_unit) { mock_model(InventoryUnit).as_null_object }

describe "GET index" do
  let(:collection) { mock("collection") }
  before { controller.stub :collection => collection }

  it 'should GET list of Inventory Units' do
    get uri_for("/inventory_units.json"), nil, user_request(@user.authentication_token)
    collection.should_receive(:to_json)
    response.should be_ok
  end
end