Add the files option

Author: DanielNoord

doc/whatsnew/fragments/5701.other

@@ -0,0 +1,7 @@
+You can now set the ``files`` option in configuration files and on the command line.
+Passing files without the ``--files`` flag is still supported. This allows to set
+``files`` to ``files = my_source_directory`` and invoking ``pylint`` with only
+the ``pylint`` command similar to how other CLI tools allow to do so.
+The help message can always be invoked with ``pylint -h`` or ``pylint --help``.
+
+Closes #5701

pylint/config/config_initialization.py

@@ -23,7 +23,7 @@ def _config_initialization(
     reporter: reporters.BaseReporter | reporters.MultiReporter | None = None,
     config_file: None | str | Path = None,
     verbose_mode: bool = False,
-) -> list[str]:
+) -> None:
     """Parse all available options, read config files and command line arguments and
     set options accordingly.
     """
@@ -119,5 +119,7 @@ def _config_initialization(
     linter._directory_namespaces[Path(".").resolve()] = (linter.config, {})
 
     # parsed_args_list should now only be a list of files/directories to lint.
-    # All other options have been removed from the list.
-    return parsed_args_list
+    # All other options have been removed from the list. If there is anything
+    # left we overwrite any 'files' as given by the configuration file.
+    if parsed_args_list:
+        linter.config.files = parsed_args_list

pylint/lint/base_options.py

@@ -401,6 +401,18 @@ def _make_linter_options(linter: PyLinter) -> Options:
                 "Useful if running pylint in a server-like mode.",
             },
         ),
+        (
+            "files",
+            {
+                "type": "csv",
+                "default": [],
+                "help": "The files to lint. The flag can also be omitted as pylint will "
+                "try to lint any file passed as argument. This can be used to set files "
+                "to a directory in a configuration file and invoke pylint by only typing "
+                "pylint on the command line. Any file passed as argument will overwrite any "
+                "file set in the configuration file.",
+            },
+        ),
     )
 
 

pylint/lint/run.py

@@ -163,7 +163,7 @@ def __init__(
         if self._is_pylint_config:
             _register_generate_config_options(linter._arg_parser)
 
-        args = _config_initialization(
+        _config_initialization(
             linter, args, reporter, config_file=self._rcfile, verbose_mode=self.verbose
         )
 
@@ -179,7 +179,7 @@ def __init__(
             return
 
         # Display help messages if there are no files to lint
-        if not args:
+        if not linter.config.files:
             print(linter.help())
             sys.exit(32)
 
@@ -203,13 +203,13 @@ def __init__(
             try:
                 with open(self._output, "w", encoding="utf-8") as output:
                     linter.reporter.out = output
-                    linter.check(args)
+                    linter.check(linter.config.files)
                     score_value = linter.generate_reports()
             except OSError as ex:
                 print(ex, file=sys.stderr)
                 sys.exit(32)
         else:
-            linter.check(args)
+            linter.check(linter.config.files)
             score_value = linter.generate_reports()
 
         if do_exit is not UNUSED_PARAM_SENTINEL:

tests/config/unittest_config.py

@@ -7,12 +7,16 @@
 from __future__ import annotations
 
 import re
+from pathlib import Path
 
 import pytest
 
 from pylint import config
 from pylint.checkers import BaseChecker
+from pylint.lint import Run as _Run
 from pylint.testutils import CheckerTestCase, set_config
+from pylint.testutils._run import _Run as Run
+from pylint.testutils.utils import _test_cwd
 from pylint.typing import MessageDefinitionTuple
 
 
@@ -86,3 +90,43 @@ def test_ignore_paths_with_no_value(self) -> None:
         options = self.linter.config.ignore_paths
 
         assert options == []
+
+
+def test_files_can_be_set_in_config(tmp_path: Path) -> None:
+    """Test that the files option can be set in a config file."""
+    with _test_cwd(tmp_path):
+        bad_file = tmp_path / "bad.py"
+        bad_file.write_text("1")
+        good_file = tmp_path / "good.py"
+        good_file.write_text("'''My module docstring'''\n")
+        init_file = tmp_path / "__init__.py"
+        init_file.write_text("")
+
+        # Test that we run on files set in the config file
+        config_file = tmp_path / "pylintrc"
+        config_file.write_text("[MASTER]\nfiles=good.py,bad.py")
+        runner = Run(["--rcfile", str(config_file)], exit=False)
+        assert runner.linter.stats.by_msg
+        # Test that we can overrun the configuration file with a command line argument
+        runner = Run(["good.py"], exit=False)
+        assert not runner.linter.stats.by_msg
+        # Or by supplying --files directly
+        runner = Run(["--files", "good.py"], exit=False)
+        assert not runner.linter.stats.by_msg
+
+        # Test that we can run on the current directory by specifying it
+        config_file = tmp_path / "pylintrc"
+        config_file.write_text("[MASTER]\nfiles=" + str(tmp_path))
+        runner = Run(["--rcfile", str(config_file)], exit=False)
+        assert runner.linter.stats.by_msg
+        # Test that we can also use just the command 'pylint'. Using _Run
+        # makes sure that the --rcfile option doesn't get patched.
+        other_runner = _Run([], exit=False)
+        assert other_runner.linter.stats.by_msg
+
+    # Test that we can also run on a directory set as files even if it is
+    # not our current cwd
+    config_file = tmp_path / "pylintrc"
+    config_file.write_text("[MASTER]\nfiles=" + str(tmp_path))
+    runner = Run(["--rcfile", str(config_file)], exit=False)
+    assert runner.linter.stats.by_msg