Tools: add script to check Python files for flake8-cleanliness

Tools/environment_install/install-prereqs-ubuntu.sh

@@ -91,7 +91,7 @@ fi
 
 # Lists of packages to install
 BASE_PKGS="build-essential ccache g++ gawk git make wget"
-PYTHON_PKGS="future lxml pymavlink MAVProxy pexpect"
+PYTHON_PKGS="future lxml pymavlink MAVProxy pexpect flake8"
 # add some Python packages required for commonly-used MAVProxy modules and hex file generation:
 if [[ $SKIP_AP_EXT_ENV -ne 1 ]]; then
   PYTHON_PKGS="$PYTHON_PKGS pygame intelhex"

Tools/scripts/build_ci.sh

@@ -259,6 +259,12 @@ for t in $CI_BUILD_TARGET; do
         continue
     fi
 
+    if [ "$t" == "python-cleanliness" ]; then
+        echo "Checking Python code cleanliness"
+        ./Tools/scripts/run_flake8.py
+        continue
+    fi
+
     if [ "$t" == "configure-all" ]; then
         echo "Checking configure of all boards"
         ./Tools/scripts/configure_all.py

Tools/scripts/run_flake8.py

@@ -0,0 +1,53 @@
+#!/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):
+        self.retcode = 0
+
+    def progress(self, string):
+        print("****** %s" % (string,))
+
+    def check(self, filepath):
+        self.progress("Checking (%s)" % filepath)
+        retcode = subprocess.call(["flake8", filepath])
+        if retcode != 0:
+            self.progress("File (%s) failed with retcode (%s)" %
+                          (filepath, retcode))
+            self.retcode = 1
+
+    def run(self):
+        for (dirpath, dirnames, filenames) in os.walk("Tools"):
+            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.check(filepath)
+        return self.retcode
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description='Check all Python files for flake8 cleanliness')
+    # parser.add_argument('--build', action='store_true', default=False, help='build as well as configure')
+    args = parser.parse_args()
+
+    checker = Flake8Checker()
+    sys.exit(checker.run())