diff --git a/tools/cover.sh b/tools/cover.sh
new file mode 100644
index 0000000000..314c492b79
--- /dev/null
+++ b/tools/cover.sh
@@ -0,0 +1,72 @@
+#!/bin/bash
+#
+# 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.
+
+# Code from https://github.com/openstack/rally/blob/master/tests/ci/cover.sh
+
+ALLOWED_EXTRA_MISSING=0
+
+show_diff () {
+    head -1 $1
+    diff -U 0 $1 $2 | sed 1,2d
+}
+
+# Stash uncommitted changes, checkout master and save coverage report
+uncommited=$(git status --porcelain | grep -v "^??")
+[[ -n $uncommited ]] && git stash > /dev/null
+git checkout HEAD^
+
+baseline_report=$(mktemp -t keystone_coverageXXXXXXX)
+find . -type f -name "*.pyc" -delete && python setup.py testr --coverage --testr-args="$*"
+coverage report > $baseline_report
+cat $baseline_report
+baseline_missing=$(awk 'END { print $3 }' $baseline_report)
+
+# Checkout back and unstash uncommitted changes (if any)
+git checkout -
+[[ -n $uncommited ]] && git stash pop > /dev/null
+
+# Generate and save coverage report
+current_report=$(mktemp -t keystone_coverageXXXXXXX)
+find . -type f -name "*.pyc" -delete && python setup.py testr --coverage --testr-args="$*"
+coverage report > $current_report
+current_missing=$(awk 'END { print $3 }' $current_report)
+
+# Show coverage details
+allowed_missing=$((baseline_missing+ALLOWED_EXTRA_MISSING))
+
+echo "Allowed to introduce missing lines : ${ALLOWED_EXTRA_MISSING}"
+echo "Missing lines in master            : ${baseline_missing}"
+echo "Missing lines in proposed change   : ${current_missing}"
+
+if [ $allowed_missing -ge $current_missing ];
+then
+    if [ $baseline_missing -lt $current_missing ];
+    then
+        show_diff $baseline_report $current_report
+        echo "I believe you can cover all your code with 100% coverage!"
+    else
+        echo "Thank you! You are awesome! Keep writing unit tests! :)"
+    fi
+    exit_code=0
+else
+    show_diff $baseline_report $current_report
+    echo "Please write more unit tests, we should keep our test coverage :( "
+    exit_code=1
+fi
+
+rm $baseline_report $current_report
+exit $exit_code
\ No newline at end of file
diff --git a/tox.ini b/tox.ini
index e5d2b13ec6..c026a1263c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -64,6 +64,10 @@ commands =
   find keystone -type f -name "*.pyc" -delete
   python setup.py testr --coverage --testr-args='{posargs}'
 
+[testenv:patch_cover]
+commands =
+  bash tools/cover.sh
+
 [testenv:venv]
 commands = {posargs}