```ruby
require 'test_helper'

class ErdIndexTest < ActionDispatch::IntegrationTest
  test 'with author and book model' do
    visit '/erd'
    assert has_content? 'Author', minimum: 1
    assert has_content? 'name'
    assert has_content? 'Book'
    assert has_content? 'title'
  end
end
```

Make sure that the test app is properly working
user
```ruby
require 'test_helper'

class ErdIndexTest < ActionDispatch::IntegrationTest
  test 'with author and book model' do
    visit '/erd'

    assert_equal 200, page.status_code
    assert has_content? 'Author', minimum: 1
    assert has_content? 'name'
    assert has_content? 'Book'
    assert has_content? 'title'
  end
end
```
assistant