.github: add flake8 cleanliness checking

.github/workflows/python-cleanliness.yml

@@ -0,0 +1,25 @@
+name: test Python cleanliness
+
+on: [push, pull_request, workflow_dispatch]
+
+concurrency:
+  group: ci-${{github.workflow}}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    runs-on: ubuntu-22.04
+
+    steps:
+      # git checkout the PR
+      - uses: actions/checkout@v4
+        with:
+          submodules: 'recursive'
+
+      - name: Install dependencies
+        run: |
+          python -m pip install -U flake8
+
+      - name: Check Python with Flake8
+        run: |
+            scripts/run_flake8.py MAVProxy

scripts/run_flake8.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python
+
+"""
+Runs flake8 over Python files which contain a marker indicating
+they are clean, ensures that they actually are
+
+ AP_FLAKE8_CLEAN
+"""
+
+import os
+import subprocess
+import sys
+
+import argparse
+
+os.environ['PYTHONUNBUFFERED'] = '1'
+
+
+class Flake8Checker(object):
+    def __init__(self, basedirs):
+        self.retcode = 0
+        self.files_to_check = []
+        self.basedirs = basedirs
+
+    def progress(self, string):
+        print("****** %s" % (string,))
+
+    def check(self):
+        if len(self.files_to_check) == 0:
+            return
+        for path in self.files_to_check:
+            self.progress("Checking (%s)" % path)
+        ret = subprocess.run(["flake8", "--show-source"] + self.files_to_check,
+                             stdout=subprocess.PIPE, stderr=subprocess.STDOUT, text=True)
+        if ret.returncode != 0:
+            self.progress("Flake8 check failed: (%s)" % (ret.stdout))
+            self.retcode = 1
+
+    def run(self):
+        for basedir in self.basedirs:
+            for (dirpath, dirnames, filenames) in os.walk(basedir):
+                for filename in filenames:
+                    if os.path.splitext(filename)[1] != ".py":
+                        continue
+                    filepath = os.path.join(dirpath, filename)
+                    content = open(filepath).read()
+                    if "AP_FLAKE8_CLEAN" not in content:
+                        continue
+                    self.files_to_check.append(filepath)
+        self.check()
+        return self.retcode
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description='Check all Python files for flake8 cleanliness')
+    parser.add_argument('DIRPATH', nargs="+", default=[], help='directory to recurse into')
+    args = parser.parse_args()
+
+    checker = Flake8Checker(args.DIRPATH)
+    sys.exit(checker.run())