Add the --style option

docs/usage.rst

@@ -9,6 +9,7 @@ Current usage of ``pydocstringformatter``:
                                 [--exit-code] [--max-summary-lines int]
                                 [--summary-quotes-same-line]
                                 [--max-line-length int]
+                                [--style {pep257} [{pep257} ...]]
                                 [--strip-whitespaces  --no-strip-whitespaces]
                                 [--split-summary-body  --no-split-summary-body]
                                 [--linewrap-full-docstring  --no-linewrap-full-docstring]
@@ -44,6 +45,9 @@ Current usage of ``pydocstringformatter``:
                             is enforced for single line docstrings.
       --max-line-length int
                             Maximum line length of docstrings.
+      --style {pep257} [{pep257} ...]
+                            Docstring styles that are used in the project. Can be
+                            more than one.
 
     default formatters:
       these formatters are turned on by default

pydocstringformatter/_configuration/arguments_manager.py

@@ -118,14 +118,23 @@ def register_arguments(self, version: str) -> None:
             metavar="int",
         )
 
+        self.configuration_group.add_argument(
+            "--style",
+            action="extend",
+            type=str,
+            nargs="+",
+            choices=["pep257"],
+            help="Docstring styles that are used in the project. Can be more than one.",
+        )
+
     def parse_options(
         self,
         argv: list[str],
     ) -> None:
         """Load all default option values.
 
         The order of parsing is:
-        1. configuration files, 2. command line arguments.
+        1. configuration files, 2. command line arguments, 3. set default values.
         """
         # pylint: disable=protected-access
         toml_parsing.parse_toml_file(self.parser, self.namespace)
@@ -134,6 +143,11 @@ def parse_options(
             self.parser, self.namespace, argv
         )
 
+        # 'style' uses the 'extend' action. If we use a normal default value,
+        # and the default gets supplied as well style == ["pep257", "pep257"].
+        if self.namespace.style is None:
+            self.namespace.style = ["pep257"]
+
     def print_help(self) -> None:
         """Print the help or usage message."""
         self.parser.print_help()

tests/test_config.py

@@ -7,6 +7,7 @@
 
 import pydocstringformatter
 from pydocstringformatter._utils import exceptions
+from pydocstringformatter.run import _Run
 
 HERE = Path(__file__)
 CONFIG_DATA = HERE.parent / "data" / "config"
@@ -225,3 +226,27 @@ def test_quiet_argument(capsys: pytest.CaptureFixture[str], test_file: str) -> N
         output = capsys.readouterr()
         assert not output.out
         assert not output.err
+
+
+class TestStyleOption:
+    """Tests for the --style option."""
+
+    def test_style_default(self, test_file: str) -> None:
+        """Test that the default value of --style is pep257."""
+        run = _Run([test_file])
+        assert run.config.style == ["pep257"]
+
+    def test_style_pep257(self, test_file: str) -> None:
+        """Test that we don't duplicate the default value if we pass it again."""
+        run = _Run([test_file, "--style", "pep257"])
+        assert run.config.style == ["pep257"]
+
+    def test_style_invalid_choice(self, capsys: pytest.CaptureFixture[str]) -> None:
+        """Test that we correctly reject invalid styles."""
+        with pytest.raises(SystemExit) as excinfo:
+            _Run(["--style", "invalid"])
+        assert excinfo.value.code == 2
+
+        output = capsys.readouterr()
+        assert not output.out
+        assert "--style: invalid choice: 'invalid'" in output.err