Add a GN format presubmit. (flutter/engine#8371)

engine/src/flutter/ci/check_gn_format.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python
+#
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import sys
+import subprocess
+import os
+import argparse
+import errno
+import shutil
+
+def GetGNFiles(directory):
+  directory = os.path.abspath(directory)
+  gn_files = []
+  assert os.path.exists(directory), "Directory must exist %s" % directory
+  for root, dirs, files in os.walk(directory):
+    for file in files:
+        if file.endswith(".gn") or file.endswith(".gni"):
+          gn_files.append(os.path.join(root, file))
+  return gn_files
+
+def main():
+  parser = argparse.ArgumentParser();
+
+  parser.add_argument('--gn-binary', dest='gn_binary', required=True, type=str)
+  parser.add_argument('--dry-run', dest='dry_run', required=True, type=bool)
+  parser.add_argument('--root-directory', dest='root_directory', required=True, type=str)
+
+  args = parser.parse_args()
+
+  gn_binary = os.path.abspath(args.gn_binary)
+  assert os.path.exists(gn_binary), "GN Binary must exist %s" % gn_binary
+
+  gn_command = [ gn_binary, 'format']
+
+  if args.dry_run:
+    gn_command.append('--dry-run')
+
+
+  for gn_file in GetGNFiles(args.root_directory):
+    if subprocess.call(gn_command + [ gn_file ]) != 0:
+      print "ERROR: '%s' is incorrectly formatted." % os.path.relpath(gn_file, args.root_directory)
+      print "Format the same with 'gn format' using the 'gn' binary in //buildtools."
+      print "Or, run ./ci/check_gn_format.py with '--dry-run false'" 
+      return -1
+
+  return 0
+
+if __name__ == '__main__':
+  sys.exit(main())

engine/src/flutter/ci/format.sh

@@ -73,3 +73,6 @@ if [[ ! -z "$TRAILING_SPACES" ]]; then
   echo "ERROR: Some files have trailing spaces. To fix, try something like \`find . -name "*.dart" -exec sed -i -e 's/\s\+$//' {} \;\`."
   exit 1
 fi
+
+# Check GN format consistency
+./ci/check_gn_format.py --dry-run true --root-directory . --gn-binary "../buildtools/$OS/gn"