old_contents: 'use strict'
  
  class FactoryInterface {
    create () {
      throw new Error('Unimplemented method')
    }
  }
  
  module.exports = FactoryInterface
  
new_contents: 'use strict'
  
  class FactoryInterface {
    static create () {
      throw new Error('Unimplemented method')
    }
  }
  
  module.exports = FactoryInterface
  
subject: Fix factory interface, now uses static method