The Test tab is located in the top menu when creating a new CMS website page. Under this tab there is the title 'Setup'. This is where you can create tests. To create a test simply click 'Add' located down the bottom of the screen.
Clicking 'Add' will bring up the following screen....
Creating a Test:
On this page the tester has a few options:
Clicking Ok will bring you back to the 'Test' panel when you will be able to see the list of tests you have created. The test that you created will show on the bottom of the list.
To run the tests go to the page you wish to run the tests on, go up to the URL bar and look for the line "CMS_MODE=PREVIEW" and change this value to "CMS_MODE=TEST";
The tests will automatically start running. If a test fails a popup will notify you of the failure so the issue can be addressed.