Test whether a form field exists with Cucumber and Capybara

The step definition below lets you say:

 Then I should see a field "Password"
 But I should not see a field "Role"

Here is the step definition:

Then /^I should( not)? see a field "([^"]*)"$/ do |negate, name|
  expectation = negate ? :should_not : :should
  begin
    field = find_field(name)
  rescue Capybara::ElementNotFound
    # In Capybara 0.4+ #find_field raises an error instead of returning nil
  end
  field.send(expectation, be_present)
end

Note that you might have to adapt the step definition for older Capybaras. Unfortunately the Capybara API wasn't very stable over time.