```ruby
require 'test_helper'
require 'pry'

describe 'Feature Integration' do

  before do
    clear_emails

    visit root_path
    fill_in 'email', with: 'test@email.com'
    click_on 'Send email'

    open_email('test@email.com') # sets current_email
  end

  it 'logs in a user when provided an email' do
    current_email.first(:link).click
    page.must_have_content 'success'
  end

  # it 'logs in a user with an optional passcode'

end
```

Make sure login links only work once
user
```ruby
require 'test_helper'
require 'pry'

describe 'Feature Integration' do

  before do
    clear_emails

    visit root_path
    fill_in 'email', with: 'test@email.com'
    click_on 'Send email'

    open_email('test@email.com') # sets current_email
  end

  it 'logs in a user when provided an email' do
    current_email.first(:link).click
    page.must_have_content 'success'
  end

  it 'only works once' do
    current_email.first(:link).click
    current_email.first(:link).click
    page.must_have_content 'failed'
  end

  # it 'logs in a user with an optional passcode'

end
```
assistant