chore(linters): Introduce ruff and fix issues

.pre-commit-config.yaml

@@ -98,6 +98,15 @@ repos:
   - id: shellcheck
 
 # Python
+- repo: https://github.com/astral-sh/ruff-pre-commit
+  rev: v0.8.4
+  hooks:
+  - id: ruff
+    args:
+    - --fix
+  - id: ruff-format
+    exclude: /terraform_docs_replace(_test)?\.py$
+
 - repo: https://github.com/pre-commit/mirrors-mypy.git
   rev: v1.15.0
   hooks:

ruff.toml

@@ -0,0 +1,39 @@
+# Assume Python 3.9
+target-version = "py39"
+
+line-length = 79 # To decrease PR diff size
+
+namespace-packages = ["src/pre_commit_terraform/", "tests/pytest/"]
+
+[format]
+quote-style = "single"
+
+[lint.flake8-quotes]
+inline-quotes = "single"
+
+[lint.pydocstyle]
+convention = "pep257"
+
+[lint]
+select = ["ALL"]
+preview = true
+ignore = [
+  "CPY001", # Missing copyright notice at top of file
+]
+
+[lint.isort]
+# force-single-line = true # To decrease PR diff size
+lines-after-imports = 2
+
+[lint.flake8-pytest-style]
+parametrize-values-type = "tuple"
+
+[lint.per-file-ignores]
+# Ignore in the `tests/` directory.
+"tests/**.py" = [
+  "S101", # Use of `assert` detected
+  "PLC2701", # We need import marked as internal files for testing
+]
+
+"src/pre_commit_terraform/terraform_docs_replace.py" = ["ALL"] # Deprecated hook
+"tests/pytest/terraform_docs_replace_test.py" = ["ALL"] # Tests for deprecated hook

src/pre_commit_terraform/__main__.py

@@ -1,6 +1,7 @@
 """A runpy-style CLI entry-point module."""
 
-from sys import argv, exit as exit_with_return_code
+from sys import argv
+from sys import exit as exit_with_return_code
 
 from ._cli import invoke_cli_app
 

src/pre_commit_terraform/_cli.py

@@ -18,35 +18,41 @@ def invoke_cli_app(cli_args: list[str]) -> ReturnCodeType:
 
     Includes initializing parsers of all the sub-apps and
     choosing what to execute.
+
+    Returns:
+        ReturnCodeType: The return code of the app.
+
+    Raises:
+        PreCommitTerraformExit: If the app is exiting with error.
     """
     root_cli_parser = initialize_argument_parser()
     parsed_cli_args = root_cli_parser.parse_args(cli_args)
     invoke_cli_app = cast_to(
-        # FIXME: attempt typing per https://stackoverflow.com/a/75666611/595220
-        CLIAppEntryPointCallableType,
+        # FIXME: attempt typing per https://stackoverflow.com/a/75666611/595220  # noqa: TD001, TD002, TD003, FIX001, E501
+        'CLIAppEntryPointCallableType',
         parsed_cli_args.invoke_cli_app,
     )
 
     try:
         return invoke_cli_app(parsed_cli_args)
     except PreCommitTerraformExit as exit_err:
-        print(f'App exiting: {exit_err !s}', file=sys.stderr)
+        print(f'App exiting: {exit_err !s}', file=sys.stderr)  # noqa: T201 FIXME
         raise
     except PreCommitTerraformRuntimeError as unhandled_exc:
-        print(
+        print(  # noqa: T201 FIXME
             f'App execution took an unexpected turn: {unhandled_exc !s}. '
             'Exiting...',
             file=sys.stderr,
         )
         return ReturnCode.ERROR
     except PreCommitTerraformBaseError as unhandled_exc:
-        print(
+        print(  # noqa: T201 FIXME
             f'A surprising exception happened: {unhandled_exc !s}. Exiting...',
             file=sys.stderr,
         )
         return ReturnCode.ERROR
     except KeyboardInterrupt as ctrl_c_exc:
-        print(
+        print(  # noqa: T201 FIXME
             f'User-initiated interrupt: {ctrl_c_exc !s}. Exiting...',
             file=sys.stderr,
         )

src/pre_commit_terraform/_cli_parsing.py

@@ -22,15 +22,22 @@ def attach_subcommand_parsers_to(root_cli_parser: ArgumentParser, /) -> None:
         required=True,
     )
     for subcommand_module in SUBCOMMAND_MODULES:
-        subcommand_parser = subcommand_parsers.add_parser(subcommand_module.CLI_SUBCOMMAND_NAME)
+        subcommand_parser = subcommand_parsers.add_parser(
+            subcommand_module.CLI_SUBCOMMAND_NAME,
+        )
         subcommand_parser.set_defaults(
             invoke_cli_app=subcommand_module.invoke_cli_app,
         )
         subcommand_module.populate_argument_parser(subcommand_parser)
 
 
 def initialize_argument_parser() -> ArgumentParser:
-    """Return the root argument parser with sub-commands."""
+    """Return the root argument parser with sub-commands.
+
+    Returns:
+        ArgumentParser: The root parser with sub-commands attached.
+
+    """
     root_cli_parser = ArgumentParser(prog=f'python -m {__package__ !s}')
     attach_subcommand_parsers_to(root_cli_parser)
     return root_cli_parser

src/pre_commit_terraform/_errors.py

@@ -6,11 +6,11 @@ class PreCommitTerraformBaseError(Exception):
 
 
 class PreCommitTerraformRuntimeError(
-        PreCommitTerraformBaseError,
-        RuntimeError,
+    PreCommitTerraformBaseError,
+    RuntimeError,
 ):
     """An exception representing a runtime error condition."""
 
 
-class PreCommitTerraformExit(PreCommitTerraformBaseError, SystemExit):
+class PreCommitTerraformExit(PreCommitTerraformBaseError, SystemExit):  # noqa: N818 FIXME
     """An exception for terminating execution from deep app layers."""

src/pre_commit_terraform/_types.py

@@ -18,7 +18,8 @@ class CLISubcommandModuleProtocol(Protocol):
     """This constant contains a CLI."""
 
     def populate_argument_parser(
-            self, subcommand_parser: ArgumentParser,
+        self,
+        subcommand_parser: ArgumentParser,
     ) -> None:
         """Run a module hook for populating the subcommand parser."""
 

tests/pytest/_cli_test.py

@@ -1,13 +1,13 @@
 """Tests for the high-level CLI entry point."""
 
 from argparse import ArgumentParser, Namespace
-import pytest
 
+import pytest
 from pre_commit_terraform import _cli_parsing as _cli_parsing_mod
 from pre_commit_terraform._cli import invoke_cli_app
 from pre_commit_terraform._errors import (
-    PreCommitTerraformExit,
     PreCommitTerraformBaseError,
+    PreCommitTerraformExit,
     PreCommitTerraformRuntimeError,
 )
 from pre_commit_terraform._structs import ReturnCode
@@ -23,7 +23,6 @@
 @pytest.mark.parametrize(
     ('raised_error', 'expected_stderr'),
     (
-        # pytest.param(PreCommitTerraformExit('sentinel'), 'App exiting: sentinel', id='app-exit'),
         pytest.param(
             PreCommitTerraformRuntimeError('sentinel'),
             'App execution took an unexpected turn: sentinel. Exiting...',
@@ -42,21 +41,23 @@
     ),
 )
 def test_known_interrupts(
-        capsys: pytest.CaptureFixture[str],
-        expected_stderr: str,
-        monkeypatch: pytest.MonkeyPatch,
-        raised_error: BaseException,
+    capsys: pytest.CaptureFixture[str],
+    expected_stderr: str,
+    monkeypatch: pytest.MonkeyPatch,
+    raised_error: BaseException,
 ) -> None:
     """Check that known interrupts are turned into return code 1."""
+
     class CustomCmdStub:
         CLI_SUBCOMMAND_NAME = 'sentinel'
 
-        def populate_argument_parser(
-                self, subcommand_parser: ArgumentParser,
+        def populate_argument_parser(  # noqa: PLR6301
+            self,
+            subcommand_parser: ArgumentParser,  # noqa: ARG002
         ) -> None:
             return None
 
-        def invoke_cli_app(self, parsed_cli_args: Namespace) -> ReturnCodeType:
+        def invoke_cli_app(self, parsed_cli_args: Namespace) -> ReturnCodeType:  # noqa: PLR6301, ARG002
             raise raised_error
 
     monkeypatch.setattr(
@@ -65,35 +66,41 @@ def invoke_cli_app(self, parsed_cli_args: Namespace) -> ReturnCodeType:
         [CustomCmdStub()],
     )
 
-    assert ReturnCode.ERROR == invoke_cli_app(['sentinel'])
+    assert invoke_cli_app(['sentinel']) == ReturnCode.ERROR
 
     captured_outputs = capsys.readouterr()
     assert captured_outputs.err == f'{expected_stderr !s}\n'
 
 
 def test_app_exit(
-        capsys: pytest.CaptureFixture[str],
-        monkeypatch: pytest.MonkeyPatch,
+    capsys: pytest.CaptureFixture[str],
+    monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     """Check that an exit exception is re-raised."""
+
     class CustomCmdStub:
         CLI_SUBCOMMAND_NAME = 'sentinel'
 
-        def populate_argument_parser(
-                self, subcommand_parser: ArgumentParser,
+        def populate_argument_parser(  # noqa: PLR6301
+            self,
+            subcommand_parser: ArgumentParser,  # noqa: ARG002
         ) -> None:
             return None
 
-        def invoke_cli_app(self, parsed_cli_args: Namespace) -> ReturnCodeType:
-            raise PreCommitTerraformExit('sentinel')
+        def invoke_cli_app(  # noqa: PLR6301
+            self,
+            parsed_cli_args: Namespace,  # noqa: ARG002
+        ) -> ReturnCodeType:
+            err = 'sentinel'
+            raise PreCommitTerraformExit(err)
 
     monkeypatch.setattr(
         _cli_parsing_mod,
         'SUBCOMMAND_MODULES',
         [CustomCmdStub()],
     )
 
-    with pytest.raises(PreCommitTerraformExit, match='^sentinel$'):
+    with pytest.raises(PreCommitTerraformExit, match=r'^sentinel$'):
         invoke_cli_app(['sentinel'])
 
     captured_outputs = capsys.readouterr()