refactor: build options for the Black call in a helper method [black-…

…as-plugin]

Thanks @clintonsteiner!

src/darker/formatters/black_formatter.py

@@ -153,6 +153,23 @@ def run(self, content: TextDocument) -> TextDocument:
  :return: The reformatted content
 
  """
+ contents_for_black = content.string_with_newline("\n")
+ if contents_for_black.strip():
+ dst_contents = format_str(
+ contents_for_black, mode=self._make_black_options()
+ )
+ else:
+ # The custom handling of empty and all-whitespace files was needed until
+ # Black 22.12.0. See https:/psf/black/pull/2484
+ dst_contents = "\n" if "\n" in content.string else ""
+ return TextDocument.from_str(
+ dst_contents,
+ encoding=content.encoding,
+ override_newline=content.newline,
+ )
+
+ def _make_black_options(self) -> Mode:
+ """Create a Black ``Mode`` object from the configuration options."""
  # Collect relevant Black configuration options from ``self.config`` in order to
  # pass them to Black's ``format_str()``. File exclusion options aren't needed
  # since at this point we already have a single file's content to work on.
@@ -182,19 +199,7 @@ def run(self, content: TextDocument) -> TextDocument:
  mode["string_normalization"] = not self.config["skip_string_normalization"]
  if "preview" in self.config:
  mode["preview"] = self.config["preview"]
-
- contents_for_black = content.string_with_newline("\n")
- if contents_for_black.strip():
- dst_contents = format_str(contents_for_black, mode=Mode(**mode))
- else:
- # The custom handling of empty and all-whitespace files was needed until
- # Black 22.12.0. See https:/psf/black/pull/2484
- dst_contents = "\n" if "\n" in content.string else ""
- return TextDocument.from_str(
- dst_contents,
- encoding=content.encoding,
- override_newline=content.newline,
- )
+ return Mode(**mode)
 
  def get_config_path(self) -> str | None:
  """Get the path of the Black configuration file."""