Compare test coverage with the master branch

* checkout one commit before the latest and check coverage
* check coverage with the latest commit
* all new lines must be tested

This functionallity essentially compares the current change
with the master branch, since the coverage job runs always
for only one change.

Partial-Bug: #1511667
Change-Id: I2ab9078489f30dbc383c068bb9abc0f3b9ee0e62

.gitignore

@@ -24,6 +24,7 @@ pip-log.txt
 # Unit test / coverage reports
 .coverage
 cover
+cover-master
 .tox
 nosetests.xml
 .testrepository

cover.sh

@@ -0,0 +1,71 @@
+#!/bin/bash
+#
+#    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.
+
+ALLOWED_EXTRA_MISSING=0
+
+show_diff () {
+    head -1 $1
+    diff -U 0 $1 $2 | sed 1,2d
+}
+
+if ! git diff --exit-code || ! git diff --cached --exit-code
+then
+    echo "There are uncommited changes!"
+    echo "Please clean git working directory and try again"
+    exit 1
+fi
+
+# Checkout master and save coverage report
+git checkout HEAD^
+
+baseline_report=$(mktemp -t magnum_coverageXXXXXXX)
+find . -type f -name "*.pyc" -delete && python setup.py testr --coverage --testr-args="$*"
+coverage report > $baseline_report
+mv cover cover-master
+cat $baseline_report
+baseline_missing=$(awk 'END { print $3 }' $baseline_report)
+
+# Checkout back and save coverage report
+git checkout -
+
+current_report=$(mktemp -t magnum_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 "We believe you can test 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 must maintain our test coverage :( "
+    exit_code=1
+fi
+
+rm $baseline_report $current_report
+exit $exit_code

tox.ini

@@ -100,8 +100,7 @@ deps = -r{toxinidir}/test-requirements.txt
 commands = bandit -r magnum -x tests -n5 -ll
 
 [testenv:cover]
-commands = python setup.py testr --coverage --testr-args='{posargs}'
-           coverage report
+commands = {toxinidir}/cover.sh {posargs}
 
 [testenv:docs]
 commands =