Merge pull request #842 from akaihola/better-missing-black-error

Improve run-time error when Black missing

Author: akaihola

src/darker/formatters/black_wrapper.py

@@ -10,13 +10,14 @@
     import black  # noqa: F401  # pylint: disable=unused-import
 except ImportError as exc:
     logger.warning(
+        "Since Darker 3.0.0, Black is no longer installed by default. "
         "To re-format code using Black, install it using e.g."
         " `pip install 'darker[black]'` or"
         " `pip install black`"
     )
     logger.warning(
         "To use a different formatter or no formatter, select it on the"
-        " command line (e.g. `--formatter=none`) or configuration"
+        " command line (e.g. `--formatter=ruff`) or configuration"
         " (e.g. `formatter=none`)"
     )
     MESSAGE = "Can't find the Black package"

src/darker/tests/test_formatters_black.py

@@ -84,11 +84,12 @@ def test_formatter_without_black(caplog):
         record.msg for record in caplog.records if record.levelname == "WARNING"
     ] == [
         # warning 1:
+        "Since Darker 3.0.0, Black is no longer installed by default. "
         "To re-format code using Black, install it using e.g."
         " `pip install 'darker[black]'` or `pip install black`",
         # warning 2:
         "To use a different formatter or no formatter, select it on the command line"
-        " (e.g. `--formatter=none`) or configuration (e.g. `formatter=none`)",
+        " (e.g. `--formatter=ruff`) or configuration (e.g. `formatter=none`)",
     ]