Update code to use flake8-helper and ast NodeVisitor.

Author: domdfcoding

README.md

@@ -0,0 +1,98 @@
+=======================
+flake8-unused-fstrings
+=======================
+
+.. start short_desc
+
+**Flake8 plugin to catch f-strings with no fields.**
+
+.. end short_desc
+
+
+.. start shields
+
+.. list-table::
+	:stub-columns: 1
+	:widths: 10 90
+
+	* - Tests
+	  - |actions_linux| |actions_windows| |actions_macos| |coveralls|
+	* - Activity
+	  - |commits-latest| |commits-since| |maintained|
+	* - QA
+	  - |codefactor| |actions_flake8| |actions_mypy|
+	* - Other
+	  - |license| |language| |requires|
+
+.. |actions_linux| image:: https://github.com/python-formate/flake8-unused-fstrings/workflows/Linux/badge.svg
+	:target: https://github.com/python-formate/flake8-unused-fstrings/actions?query=workflow%3A%22Linux%22
+	:alt: Linux Test Status
+
+.. |actions_windows| image:: https://github.com/python-formate/flake8-unused-fstrings/workflows/Windows/badge.svg
+	:target: https://github.com/python-formate/flake8-unused-fstrings/actions?query=workflow%3A%22Windows%22
+	:alt: Windows Test Status
+
+.. |actions_macos| image:: https://github.com/python-formate/flake8-unused-fstrings/workflows/macOS/badge.svg
+	:target: https://github.com/python-formate/flake8-unused-fstrings/actions?query=workflow%3A%22macOS%22
+	:alt: macOS Test Status
+
+.. |actions_flake8| image:: https://github.com/python-formate/flake8-unused-fstrings/workflows/Flake8/badge.svg
+	:target: https://github.com/python-formate/flake8-unused-fstrings/actions?query=workflow%3A%22Flake8%22
+	:alt: Flake8 Status
+
+.. |actions_mypy| image:: https://github.com/python-formate/flake8-unused-fstrings/workflows/mypy/badge.svg
+	:target: https://github.com/python-formate/flake8-unused-fstrings/actions?query=workflow%3A%22mypy%22
+	:alt: mypy status
+
+.. |requires| image:: https://dependency-dash.repo-helper.uk/github/python-formate/flake8-unused-fstrings/badge.svg
+	:target: https://dependency-dash.repo-helper.uk/github/python-formate/flake8-unused-fstrings/
+	:alt: Requirements Status
+
+.. |coveralls| image:: https://img.shields.io/coveralls/github/python-formate/flake8-unused-fstrings/master?logo=coveralls
+	:target: https://coveralls.io/github/python-formate/flake8-unused-fstrings?branch=master
+	:alt: Coverage
+
+.. |codefactor| image:: https://img.shields.io/codefactor/grade/github/python-formate/flake8-unused-fstrings?logo=codefactor
+	:target: https://www.codefactor.io/repository/github/python-formate/flake8-unused-fstrings
+	:alt: CodeFactor Grade
+
+.. |license| image:: https://img.shields.io/github/license/python-formate/flake8-unused-fstrings
+	:target: https://github.com/python-formate/flake8-unused-fstrings/blob/master/LICENSE
+	:alt: License
+
+.. |language| image:: https://img.shields.io/github/languages/top/python-formate/flake8-unused-fstrings
+	:alt: GitHub top language
+
+.. |commits-since| image:: https://img.shields.io/github/commits-since/python-formate/flake8-unused-fstrings/v1.0.1
+	:target: https://github.com/python-formate/flake8-unused-fstrings/pulse
+	:alt: GitHub commits since tagged version
+
+.. |commits-latest| image:: https://img.shields.io/github/last-commit/python-formate/flake8-unused-fstrings
+	:target: https://github.com/python-formate/flake8-unused-fstrings/commit/master
+	:alt: GitHub last commit
+
+.. |maintained| image:: https://img.shields.io/maintenance/yes/2026
+	:alt: Maintenance
+
+.. end shields
+
+Installation
+--------------
+
+.. start installation
+
+``flake8-unused-fstrings`` can be installed from GitHub.
+
+To install with ``pip``:
+
+.. code-block:: bash
+
+	$ python -m pip install git+https://github.com/python-formate/flake8-unused-fstrings
+
+.. end installation
+
+
+Rules
+------
+
+* **NUF001**: f-string without interpolation.

README.rst

@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+#
+#  __init__.py
+"""
+Flake8 plugin to catch f-strings with no fields.
+"""
+#
+#  Copyright © 2019-2020 adam hitchcock <adam+python@northisup.com>
+#  License: ISC License (ISCL)
+#  See the LICENSE file for details.
+#
+
+# stdlib
+import ast
+
+# 3rd party
+import flake8_helper
+
+__author__: str = "adam hitchcock"
+__copyright__: str = "2019-2020 adam hitchcock"
+__license__: str = "ISC License (ISCL)"
+__version__: str = "1.0.1"
+__email__: str = "adam+python@northisup.com"
+
+__all__ = ["Plugin", "Visitor"]
+
+NUF001 = "NUF001 f-string without interpolation."
+
+
+class Visitor(flake8_helper.Visitor):
+	"""
+	AST node visitor for identifying f-strings with no fields.
+	"""
+
+	def check_joinedstring_has_formatted_value(self, node: ast.JoinedStr) -> bool:
+		return any(isinstance(value, ast.FormattedValue) for value in ast.walk(node))
+
+	def visit_JoinedStr(self, node: ast.JoinedStr) -> None:  # noqa: D102
+		is_good = self.check_joinedstring_has_formatted_value(node)
+		if not is_good:
+			self.errors.append((
+					node.lineno,
+					node.col_offset,
+					NUF001,
+					))
+
+
+class Plugin(flake8_helper.Plugin[Visitor]):
+	"""
+	A Flake8 plugin which checks for f-strings with no fields.
+
+	:param tree: The abstract syntax tree (AST) to check.
+	"""
+
+	name: str = __name__
+
+	#: The plugin version
+	version: str = __version__
+
+	visitor_class = Visitor

flake8_unused_fstrings/__init__.py

@@ -1 +1 @@
-flake8>=4
+flake8-helper>=0.1.1