```ruby
require 'jekyll'
require File.expand_path('../lib/jekyll-sitemap', __dir__)

Jekyll.logger.log_level = 5

RSpec.configure do |config|
  config.treat_symbols_as_metadata_keys_with_true_values = true
  config.run_all_when_everything_filtered = true
  config.filter_run :focus
  config.order = 'random'

  SOURCE_DIR = File.expand_path("../fixtures", __FILE__)
  DEST_DIR   = File.expand_path("../dest",     __FILE__)

  def source_dir(*files)
    File.join(SOURCE_DIR, *files)
  end

  def dest_dir(*files)
    File.join(DEST_DIR, *files)
  end
end
```

Use File.dirname(__FILE__) instead of __dir__
user
```ruby
require 'jekyll'
require File.expand_path('../lib/jekyll-sitemap', File.dirname(__FILE__))

Jekyll.logger.log_level = 5

RSpec.configure do |config|
  config.treat_symbols_as_metadata_keys_with_true_values = true
  config.run_all_when_everything_filtered = true
  config.filter_run :focus
  config.order = 'random'

  SOURCE_DIR = File.expand_path("../fixtures", __FILE__)
  DEST_DIR   = File.expand_path("../dest",     __FILE__)

  def source_dir(*files)
    File.join(SOURCE_DIR, *files)
  end

  def dest_dir(*files)
    File.join(DEST_DIR, *files)
  end
end
```
assistant