Testing this requires some manipulation of the code, given that this patch introduces a new stylelint rule, as well as the fix to a newly detected problem in the boost theme. Test 1: check that the lint tests in the grunt build pass using this patch. Run the grunt build: npm install npx grunt Verify that it passes without errors. Test 2: check that the grunt build passes, with the fix to the boost theme, and without the new stylelint plugin. Remove this line from the .stylelintrc file: "plugin/declaration-block-no-ignored-properties": true, Run the grunt build: npm install npx grunt Verify that it passes without errors. Test 3: check that the lint tests in the grunt build fail, without the patched fix to the boost theme, but with the new stylelint "no ignored properties" plugin. Restore the .stylelintrc file from the patch, i.e. ensure that this line is reinstated: "plugin/declaration-block-no-ignored-properties": true, Remove the z-index: 0 property from any CSS selector that also includes the position: static property, e.g. the .custom-control-input selector in the theme/boost/scss/moodle/debug.scss file, on line 34. Run the grunt build: npm install npx grunt Verify that the grunt build fails with an error: 34:9 ✖ Unexpected "z-index" with "position: static" plugin/declaration-block-no-ignored-properties