Make coverage job voting

Instead of asking people to write unit tests let's just make
coverage job voting.

This can be implemented in very simple maner:

1) checkout to master
2) run coverage and get base line
3) checkout back
4) run coverage to get current coverage
5) If coverage was reduced more then 0.01% mark job as failed

Change-Id: Ib6bc4dbb11c69b107e6fcd6464a4041337ea1a66

.coveragerc

@@ -4,4 +4,4 @@ source = rally
 
 [report]
 ignore-errors = True
-precision = 2
+precision = 3

tests/ci/cover.sh

@@ -0,0 +1,47 @@
+#!/bin/bash -e
+#
+# Copyright 2015: Mirantis Inc.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+
+# Checkout to master to collect base line coverage
+git stash
+git checkout master
+
+python setup.py testr --coverage --testr-args=$@
+baseline=`coverage report | tail -1 | tr " " "\n" | tail -1`
+
+# Checkout back to user directory to get current coverage
+git checkout -
+git stash pop || true
+
+python setup.py testr --coverage --testr-args=$@
+current=`coverage report | tail -1 | tr " " "\n" | tail -1 `
+
+echo "Coverage baseline: ${baseline} current: ${current}"
+
+# If coverage was reduced by 0.01% job will fail
+
+code=`python -c "base=float(\"${baseline}\"[:-1]); current=float(\"${current}\"[:-1]); print(base - current > 0.01 and 1 or 0)"`
+
+
+if [ $code -eq 0 ];
+then
+    echo "Thank you! You are awesome! Keep writing unit tests! :)"
+else
+    echo "Please write more unit tests, we should keep our test coverage :( "
+fi
+
+exit $code

tox.ini

@@ -28,7 +28,8 @@ sitepackages = True
 commands = {toxinidir}/tests/ci/rally-integrated.sh
 
 [testenv:cover]
-commands = python setup.py testr --coverage --testr-args='{posargs}'
+commands = {toxinidir}/tests/ci/cover.sh {posargs}
+
 
 [testenv:docs]
 changedir = doc/source