Add support for Ruff as a code-formatter

CHANGES.rst

@@ -19,6 +19,8 @@ Added
   other formatters in the future. There's also a dummy ``none`` formatter plugin.
 - ``--formatter=none`` now skips running Black. This is useful when you only want to run
   Isort or Flynt.
+- Black_ is no longer installed by default. Use ``pip install 'darker[black]'`` to get
+  Black support.
 
 Removed
 -------

README.rst

@@ -133,11 +133,11 @@ How?
 
 To install or upgrade, use::
 
-  pip install --upgrade darker~=2.1.1
+  pip install --upgrade darker[black]~=2.1.1
 
 Or, if you're using Conda_ for package management::
 
-  conda install -c conda-forge darker~=2.1.1 isort
+  conda install -c conda-forge darker~=2.1.1 black isort
   conda update -c conda-forge darker
 
 ..
@@ -146,6 +146,8 @@ Or, if you're using Conda_ for package management::
     specifier for Darker. See `Guarding against Black compatibility breakage`_ for more
     information.
 
+*New in version 3.0.0:* Black is no longer installed by default.
+
 The ``darker <myfile.py>`` or ``darker <directory>`` command
 reads the original file(s),
 formats them using Black_,
@@ -371,7 +373,7 @@ The following `command line arguments`_ can also be used to modify the defaults:
        versions that should be supported by Black's output. [default: per-file auto-
        detection]
 --formatter FORMATTER
-       [black\|none] Formatter to use for reformatting code. [default: black]
+       [black\|none\|ruff] Formatter to use for reformatting code. [default: black]
 
 To change default values for these options for a given project,
 add a ``[tool.darker]`` section to ``pyproject.toml`` in the project's root directory,
@@ -478,7 +480,7 @@ PyCharm/IntelliJ IDEA
 
 1. Install ``darker``::
 
-     $ pip install darker
+     $ pip install 'darker[black]'
 
 2. Locate your ``darker`` installation folder.
 
@@ -540,7 +542,7 @@ Visual Studio Code
 
 1. Install ``darker``::
 
-     $ pip install darker
+     $ pip install 'darker[black]'
 
 2. Locate your ``darker`` installation folder.
 
@@ -683,16 +685,20 @@ other reformatter tools you use to known compatible versions, for example:
 Using arguments
 ---------------
 
-You can provide arguments, such as enabling isort, by specifying ``args``.
-Note the inclusion of the isort Python package under ``additional_dependencies``:
+You can provide arguments, such as disabling Darker or enabling isort,
+by specifying ``args``.
+Note the absence of Black and the inclusion of the isort Python package
+under ``additional_dependencies``:
 
 .. code-block:: yaml
 
    - repo: https://github.com/akaihola/darker
      rev: v2.1.1
      hooks:
        - id: darker
-         args: [--isort]
+         args:
+           - --formatter=none
+           - --isort
          additional_dependencies:
            - isort~=5.9
 
@@ -779,6 +785,9 @@ The ``lint:`` option.
 Removed the ``lint:`` option and moved it into the GitHub action
 of the Graylint_ package.
 
+*New in version 3.0.0:*
+Black is now explicitly installed when running the action.
+
 
 Syntax highlighting
 ===================

action/main.py

@@ -22,7 +22,7 @@
 
 run([sys.executable, "-m", "venv", str(ENV_PATH)], check=True)  # nosec
 
-req = ["darker[color,isort]"]
+req = ["darker[black,color,isort]"]
 if VERSION:
     if VERSION.startswith("@"):
         req[0] = f"git+https://github.com/akaihola/darker{VERSION}#egg={req[0]}"

action/tests/test_main.py

@@ -91,23 +91,25 @@ def test_creates_virtualenv(tmp_path, main_patch):
 
 
 @pytest.mark.kwparametrize(
-    dict(run_main_env={}, expect=["darker[color,isort]"]),
+    dict(run_main_env={}, expect=["darker[black,color,isort]"]),
     dict(
-        run_main_env={"INPUT_VERSION": "1.5.0"}, expect=["darker[color,isort]==1.5.0"]
+        run_main_env={"INPUT_VERSION": "1.5.0"},
+        expect=["darker[black,color,isort]==1.5.0"],
     ),
     dict(
         run_main_env={"INPUT_VERSION": "@master"},
         expect=[
-            "git+https://github.com/akaihola/darker@master#egg=darker[color,isort]"
+            "git+https://github.com/akaihola/darker"
+            "@master#egg=darker[black,color,isort]"
         ],
     ),
     dict(
         run_main_env={"INPUT_LINT": "dummy"},
-        expect=["darker[color,isort]"],
+        expect=["darker[black,color,isort]"],
     ),
     dict(
         run_main_env={"INPUT_LINT": "dummy,foobar"},
-        expect=["darker[color,isort]"],
+        expect=["darker[black,color,isort]"],
     ),
 )
 def test_installs_packages(tmp_path, main_patch, run_main_env, expect):
@@ -208,15 +210,15 @@ def test_error_if_pip_fails(tmp_path, capsys):
         run_module("main")
 
     assert main_patch.subprocess.run.call_args_list[-1] == call(
-        [ANY, "-m", "pip", "install", "darker[color,isort]"],
+        [ANY, "-m", "pip", "install", "darker[black,color,isort]"],
         check=False,
         stdout=PIPE,
         stderr=STDOUT,
         encoding="utf-8",
     )
     assert (
         capsys.readouterr().out.splitlines()[-1]
-        == "::error::Failed to install darker[color,isort]."
+        == "::error::Failed to install darker[black,color,isort]."
     )
     main_patch.sys.exit.assert_called_once_with(42)
 

constraints-oldest.txt

@@ -4,7 +4,8 @@
 # interpreter and Python ependencies. Keep this up-to-date with minimum
 # versions in `setup.cfg`.
 black==22.3.0
-darkgraylib==2.0.1
+# TODO: upgrade to darkgraylib~=2.1.0 when released
+darkgraylib @ git+https://github.com/akaihola/darkgraylib.git@module-scope-git-repo-fixture
 defusedxml==0.7.1
 flake8-2020==1.6.1
 flake8-bugbear==22.1.11

setup.cfg

@@ -28,8 +28,8 @@ package_dir =
 packages = find:
 install_requires =
     # NOTE: remember to keep `constraints-oldest.txt` in sync with these
-    black>=22.3.0
-    darkgraylib~=2.0.1
+    # TODO: upgrade to darkgraylib~=2.1.0 when released
+    darkgraylib @ git+https://github.com/akaihola/darkgraylib.git@module-scope-git-repo-fixture
     toml>=0.10.0
     typing_extensions>=4.0.1
 # NOTE: remember to keep `.github/workflows/python-package.yml` in sync
@@ -47,11 +47,14 @@ darker =
 [options.entry_points]
 darker.formatter =
     black = darker.formatters.black_formatter:BlackFormatter
+    ruff = darker.formatters.ruff_formatter:RuffFormatter
     none = darker.formatters.none_formatter:NoneFormatter
 console_scripts =
     darker = darker.__main__:main_with_error_handling
 
 [options.extras_require]
+black =
+    black>=22.3.0
 flynt =
     flynt>=0.76
 isort =
@@ -95,8 +98,14 @@ ignore =
     D400
     # D415 First line should end with a period, question mark, or exclamation point
     D415
+    # E203 Whitespace before ':'
+    E203
     # E231 missing whitespace after ','
     E231
+    # E501 Line too long (82 > 79 characters)
+    E501
+    # E701 Multiple statements on one line (colon)
+    E701
     # W503 line break before binary operator
     W503
 # Darglint options when run as a Flake8 plugin:

src/darker/__main__.py

@@ -293,7 +293,7 @@ def _maybe_reformat_single_file(
     if glob_any(relpath_in_rev2, exclude):
         # File was excluded by Black configuration, don't reformat
         return fstringified
-    return formatter.run(fstringified)
+    return formatter.run(fstringified, relpath_in_rev2)
 
 
 def _drop_changes_on_unedited_lines(

src/darker/command_line.py

@@ -5,8 +5,6 @@
 from functools import partial
 from typing import List, Optional, Tuple
 
-from black import TargetVersion
-
 import darkgraylib.command_line
 from darker import help as hlp
 from darker.config import (
@@ -15,6 +13,7 @@
     DarkerConfig,
     OutputMode,
 )
+from darker.configuration.target_version import TargetVersion
 from darker.formatters import get_formatter_names
 from darker.version import __version__
 from darkgraylib.command_line import add_parser_argument

src/darker/configuration/__init__.py

@@ -0,0 +1 @@
+"""Configuration and command line handling."""

src/darker/configuration/target_version.py

@@ -0,0 +1,19 @@
+"""Data structures configuring Darker and formatter plugin behavior."""
+
+from enum import Enum
+
+
+class TargetVersion(Enum):
+    """Python version numbers."""
+
+    PY33 = 3
+    PY34 = 4
+    PY35 = 5
+    PY36 = 6
+    PY37 = 7
+    PY38 = 8
+    PY39 = 9
+    PY310 = 10
+    PY311 = 11
+    PY312 = 12
+    PY313 = 13