Run PRESUBMIT_test.py in subdirectories

Right now, changes to //PRESUBMIT.py trigger running
//PRESUBMIT_test.py during presubmit checks.

However, this does not happen for PRESUBMITs in subdirectories, of
which there is a number with associated PRESUBMIT_test. This CL allows
running the associated PRESUBMIT_test.

Bug: 821981
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation;master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I057f4d736992795dde7dd0d329ed3773d22553dc
Reviewed-on: https://chromium-review.googlesource.com/966906
Commit-Queue: Vaclav Brozek <vabr@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544318}

PRESUBMIT.py

@@ -2633,11 +2633,13 @@ def _CommonChecks(input_api, output_api):
   results.extend(input_api.RunTests(
     input_api.canned_checks.CheckVPythonSpec(input_api, output_api)))
 
-  if any('PRESUBMIT.py' == f.LocalPath() for f in input_api.AffectedFiles()):
-    results.extend(input_api.canned_checks.RunUnitTestsInDirectory(
-        input_api, output_api,
-        input_api.PresubmitLocalPath(),
-        whitelist=[r'^PRESUBMIT_test\.py$']))
+  for f in input_api.AffectedFiles():
+    path, name = input_api.os_path.split(f.LocalPath())
+    if name == 'PRESUBMIT.py':
+      full_path = input_api.os_path.join(input_api.PresubmitLocalPath(), path)
+      results.extend(input_api.canned_checks.RunUnitTestsInDirectory(
+          input_api, output_api, full_path,
+          whitelist=[r'^PRESUBMIT_test\.py$']))
   return results
 
 

chrome/browser/resources/PRESUBMIT_test.py

@@ -1,3 +1,4 @@
+#!/usr/bin/env python
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

ios/PRESUBMIT_test.py

@@ -1,3 +1,4 @@
+#!/usr/bin/env python
 # Copyright 2017 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

media/PRESUBMIT_test.py

@@ -1,3 +1,4 @@
+#!/usr/bin/env python
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

third_party/WebKit/PRESUBMIT_test.py

@@ -1,3 +1,4 @@
+#!/usr/bin/env python
 # Copyright 2017 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.