From 29b37065d75e9a95d578fc626fc9eb9c3ae0ba39 Mon Sep 17 00:00:00 2001
From: Zhenguo Niu <niuzhenguo@huawei.com>
Date: Tue, 22 Dec 2015 15:46:46 +0800
Subject: [PATCH] tox: make it possible to run pep8 on current patch only

This makes tox use a simple wrapper around flake8 like
Nova, which can be told to restrict the check to only
files changed in the current command. This can be invoked
in a simple manner with 'tox -epep8 -- -HEAD'. Since most
commits only touch a handful of files, this will usually
be far faster than checking all source files.

To check an entire branch for bisectability it can be
automated via

  git rebase -i master -x 'tox -epep8 -- -HEAD'

Change-Id: I75b1cfe3198b1217f8b25877714a4af47ae7069f
---
 tools/flake8wrap.sh | 20 ++++++++++++++++++++
 tox.ini             |  2 +-
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100755 tools/flake8wrap.sh

diff --git a/tools/flake8wrap.sh b/tools/flake8wrap.sh
new file mode 100755
index 0000000000..531b407d6a
--- /dev/null
+++ b/tools/flake8wrap.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+#
+# A simple wrapper around flake8 which makes it possible
+# to ask it to only verify files changed in the current
+# git HEAD patch.
+#
+# Intended to be invoked via tox:
+#
+#   tox -epep8 -- -HEAD
+#
+
+if test "x$1" = "x-HEAD" ; then
+    shift
+    files=$(git diff --name-only HEAD~1 | tr '\n' ' ')
+    echo "Running flake8 on ${files}"
+    diff -u --from-file /dev/null ${files} | flake8 --diff "$@"
+else
+    echo "Running flake8 on all files"
+    exec flake8 "$@"
+fi
diff --git a/tox.ini b/tox.ini
index 8b8fc53380..61f95b5339 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,7 +25,7 @@ commands = {toxinidir}/tools/states_to_dot.py -f {toxinidir}/doc/source/images/s
 [testenv:pep8]
 whitelist_externals = bash
 commands =
-  flake8 {posargs}
+  bash tools/flake8wrap.sh {posargs}
   # Run bashate during pep8 runs to ensure violations are caught by
   # the check and gate queues.
   {toxinidir}/tools/run_bashate.sh {toxinidir}/devstack