PHPUnit’s HTML code coverage reports don’t play nicely with GitHub pages “main branch /docs folder” by default, as they store CSS, JS and icon assets in folders prefixed with underscores.
Here’s a little bash script to run tests with code coverage enabled, then move the assets around:
rm -rf docs/coverage/
XDEBUG_MODE=coverage ./vendor/bin/phpunit tests --coverage-filter src --coverage-html docs/coverage
mv docs/coverage/_css docs/coverage/phpunit_css
mv docs/coverage/_icons docs/coverage/phpunit_icons
mv docs/coverage/_js docs/coverage/phpunit_js
grep -rl _css docs/coverage | xargs sed -i "" -e 's/_css/phpunit_css/g'
grep -rl _icons docs/coverage | xargs sed -i "" -e 's/_icons/phpunit_icons/g'
grep -rl _js docs/coverage | xargs sed -i "" -e 's/_js/phpunit_js/g'
That allows you to use GitHub pages to show code coverage reports as well as docs, as I’m doing for taproot/indieauth.