```ruby
require "test_helper"

class OperationalFieldTest < ActiveSupport::TestCase
  test "should be invalid without a name" do
    operational_field = build(:operational_field, name: '')
    refute operational_field.valid?
  end

  test "should be invalid without a unique name" do
    existing_operational_field = create(:operational_field)
    new_operational_field = build(:operational_field, name: existing_operational_field.name)
    refute new_operational_field.valid?
  end

  test 'should set a slug from the field name' do
    field = create(:operational_field, name: 'Field Name')
    assert_equal 'field-name', field.slug
  end

  test 'should not change the slug when the field name changes' do
    field = create(:operational_field, name: 'Field Name')
    field.update_attributes(name: 'New Field Name')
    assert_equal 'field-name', field.slug
  end
end
```

Apply styleguide rules to OperationalFieldTest
user
```ruby
require "test_helper"

class OperationalFieldTest < ActiveSupport::TestCase
  test "is invalid without a name" do
    operational_field = build(:operational_field, name: "")
    refute operational_field.valid?
  end

  test "is invalid without a unique name" do
    existing_operational_field = create(:operational_field)
    new_operational_field = build(:operational_field, name: existing_operational_field.name)
    refute new_operational_field.valid?
  end

  test "sets a slug from the field name" do
    field = create(:operational_field, name: "Field Name")
    assert_equal "field-name", field.slug
  end

  test "does not change the slug when the field name changes" do
    field = create(:operational_field, name: "Field Name")
    field.update_attributes(name: "New Field Name")
    assert_equal "field-name", field.slug
  end
end
```
assistant