ad testing

Author: Vladimir Kotal

CONTRIBUTING.md

@@ -9,5 +9,8 @@ When submitting a new Issue for what seems is a bug, please note the version you
 
 Make sure to add a comment line line to the changeset saying which Issue it is is fixing, e.g. 'fixes #XYZ' so that the issue can be automatically closed when the associated pull request is merged.
 
+Each pull request should be accompanied by a comment explaining how the change was tested, unless unit tests are provided/updated.
+Please make every effort to make most of your changes covered by tests.
+
 For a pull request to be merged, we need the contributor to sign Oracle Contributor Agreement first.
 See http://www.oracle.com/technetwork/community/oca-486395.html for details.