 
   ## Filters
 
-  ExUnit provides tags and filtering functionality that allows developers
+  ExUnit provides tags and filtering functionality that allow developers
   to select which tests to run. The most common functionality is to exclude
   some particular tests from running by default in your test helper file:
 

  end

  defp parse_files([single_file], _test_paths) do
    # Check if the single file path matches test/path/to_test.exs:123, if it does
    # apply "--only line:123" and trim the trailing :123 part.
    {single_file, opts} = ExUnit.Filters.parse_path(single_file)
    ExUnit.configure(opts)


      mix test --include external --exclude test

  In case a single file is being tested, it is possible to pass a specific
  line number:

      mix test test/some/particular/file_test.exs:12
