new_contents: from kernel.config import KernelConfig
  
  def test_from_file():
      config = KernelConfig.from_file("examples/user.config")
      assert "CONFIG_USB_STORAGE" in config.options
      assert "CONFIG_USB_STORAGE_DEBUG" in config.options
      assert "CONFIG_USB_STORAGE_REALTEK" not in config.options
  
subject: add a basic test for KernelConfig