Testing instructions stolen from MDL-56010 Create this test template in lib/templates/test.mustache {{! @template core/test Testing template. Example context (json): { "messa"ge": "Your pants are on fire!" } }} <div class="alert alert-success">{{{message}}}</div> Set debugging to 'Developer'. Go to the Template Library admin tool and view the test template with your javascript console open. Confirm that you see "Could not parse json example context for template." with a stack trace etc. Set the loglevel to "None". You may need to force a cache reload. Repeat the test. Confirm that you don't see any message in the javascript console this time.