From a7471dd773d498c0ba5503d9f512ac3342a7a6e3 Mon Sep 17 00:00:00 2001
From: "Daniel P. Berrange" <berrange@redhat.com>
Date: Fri, 24 Jul 2015 16:05:49 +0100
Subject: [PATCH] tox: make it possible to run pep8 on current patch only

The 'tox -epep8' command takes a long time as it checks
every single file in the Nova git repository (~1,400 at
time of writing).

This makes tox use a simple wrapper around flake8 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 1,400 source files.

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

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

Change-Id: I157d1ccb883ca02402eee51fd7d6a50f86079389
---
 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 000000000000..ab3269df7fb2
--- /dev/null
+++ b/tools/flake8wrap.sh
@@ -0,0 +1,20 @@
+#!/bin/sh
+#
+# 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 adda316ae22b..dee68ebfbe56 100644
--- a/tox.ini
+++ b/tox.ini
@@ -27,7 +27,7 @@ downloadcache = ~/cache/pip
 
 [testenv:pep8]
 commands =
-  flake8 {posargs}
+  bash tools/flake8wrap.sh {posargs}
 
 [testenv:py34]
 setenv = {[testenv]setenv}