CACHE_DISABLE_ALL should not disable cache_data_sources

Test 1

1. Open your config.php in your preferred editor
2. At the top of the file, just beneath the PHP open tag (<?php) add:

   define('CACHE_DISABLE_ALL', true);

3. Log in as editing teacher or above
4. Navigate to a course
5. From the cog, choose More
6. Navigate to Question bank -> Questions
7. Create a new question (any question will do)
8. Locate the newly created question in the question bank
9. From the Edit menu, choose "Preview"
   1. Confirm that a new window opened
   2. Confirm that no errors were shown on the page

Test 2

1. Download the attached testcache.php and save it in the Root of you Moodle install where you run PHPunit.
2. Run it in the CLI: php testcache.php nocache.
   1. Confirm that there were no assertion failures