Testing Simpleform Inputs

RSpec.describe LikertInput, type: :input do
  class MockTemplate
    include ActionView::Helpers
    attr_accessor :output_buffer
  end

  let(:object)        { double(:object, happiness: '1') }
  let(:builder)       { double(:builder, object: object) }
  let(:input_options) { { value: '1', class: 'input-small' } }

  subject do
    described_class.new(builder, :happiness, :happiness, :likert)
  end

  before do
    allow(subject).to receive(:template).and_return(MockTemplate.new)
    expect(builder).to receive(:select)
      .with(:happiness, LikertOption.to_a, input_options).and_return("select tag")
    expect(subject).to receive(:input_html_options).and_return({})
  end

  specify do
    expect(subject.input).to eq('<div class="input-append likert">select tag</div>')
  end
end

An improvement would be to check the actual template output_buffer