erro estranho

gistfile1.rb

  scenario "Relacionar professor com turmas", :driver => :selenium do
    periodo_letivo = PeriodoLetivo.create! :sigla => '2012/1', :inicio => Date.today, :termino => Date.tomorrow
    professor = Professor.create! :nome => 'Senhor Professor', :email => 'professor@internet.com', :password => 'password'
    visit new_disciplina_path
    logar_admin('admin@test.com', '123456')

    fill_in :nome, with: 'Calculo'
    fill_in :credito, with: 4
    page.driver.browser.save_screenshot 'screenshot.png'
    select '2012/1' , from: 'Periodo letivos'
    click_button 'Create Disciplina'

    page.should have_content 'Disciplina was successfully created.'
  end