RSPEC Controller spec #Testing non-HTML controller output

gistfile1.rb

# link_to 'Export', messages_path(format: :csv)
describe 'CSVoutput' do
  it "returns a CSV file" do 
    get :index, format: :csv
    expect(response.headers['Content-Type']).to have_content 'text/csv' 
  end
  
  it 'returns content' do 
    create(:message,
      name: 'Aaron',
      email: '[email protected]',
      message: 'Testing!')
    get :index, format: :csv
    response.body.should have_content 'Aaron,[email protected],Testing!'
    expect(response.body).to have_content 'Aaron,[email protected],Testing!'
  end
end