Stolen from MDL-52651 Create a forum. In a discussion, add in HTML links with and without the target attribute. Note: You will need to only use the value _blank for target as other values are filtered out. Save. View the discussion and verify that any links that have the target attribute will have rel=noreferrer attribute added. Make sure the when opening a target="_blank" link that the original page is not redirected. Try the same sort of thing in other text areas and see if any don't add the attribute. Example: This: <a href="http://allthethings.co.nz/moodle/redirect.html" target="_blank">Test my link</a>   Becomes: <a href="http://allthethings.co.nz/moodle/redirect.html" target="_blank" rel="noreferrer" id="yui_3_15_0_3_1425447153706_281">Test my link</a> Run all unit tests and check that failures don't relate to this issue.