Disable DEBUG_DEVELOPER In your config.php, set: $CFG->yuisplitmodulefiles = true; $CFG->yuicomboloading = false; Load a page in Moodle Open the dev tools, navigate to the Network tab, and filter on JS/Scripts, clear the list of files loaded so far (if any) Run: YUI().use('moodle-course-modchooser'); Confirm that the paths requested included yui_combo.php *Confirm that they have valid content (e.g. they're not just an error message) Confirm that the content was minified Confirm that each file was loaded separately (e.g. one module per HTTP request) Refresh the page Clear the Network tab again YUI().use('charts'); Confirm that the paths requested included yui_combo.php *Confirm that they have valid content (e.g. they're not just an error message) Confirm that the content was minified Confirm that each file was loaded separately (e.g. one module per HTTP request) Refresh the page Clear the Network tab again Run: YUI().use('yui2-graphs'); Confirm that the paths requested included yui_combo.php *Confirm that they have valid content (e.g. they're not just an error message) Confirm that the content was minified Confirm that each file was loaded separately (e.g. one module per HTTP request) Refresh the page Clear the Network tab again Run: YUI().use('gallery-sm-treeview'); Confirm that the paths requested included yui_combo.php *Confirm that they have valid content (e.g. they're not just an error message) Confirm that the content was minified Confirm that each file was loaded separately (e.g. one module per HTTP request) Set DEBUG_DEVELOPER Refresh the page Clear the Network tab again Run: YUI().use('moodle-course-modchooser'); Confirm that the paths requested included yui_combo.php *Confirm that they have valid content (e.g. they're not just an error message) Confirm that the content was minified Confirm that each file was loaded separately (e.g. one module per HTTP request) Refresh the page Clear the Network tab again Run: YUI().use('charts'); Confirm that the path included yui_combo.php *Confirm that they have valid content (e.g. they're not just an error message) Confirm that the content was not minified Confirm that each file was loaded separately (e.g. one module per HTTP request) Refresh the page Clear the Network tab again Run: YUI().use('yui2-graphs'); Confirm that the path included yui_combo.php *Confirm that they have valid content (e.g. they're not just an error message) Confirm that the content was not minified Confirm that each file was loaded separately (e.g. one module per HTTP request) Refresh the page Clear the Network tab again Run: YUI().use('gallery-sm-treeview'); Confirm that the path included yui_combo.php *Confirm that they have valid content (e.g. they're not just an error message) Confirm that the content was not minified Confirm that each file was loaded separately (e.g. one module per HTTP request) Change your config.php such that: $CFG->yuicomboloading = true; Re-run the previous test-suite confirming that the setting change has made no difference.