LayoutTests/fast/shadow-dom/shadow-style-invalidation-pseudo-element.html

<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<style>
:focus { color: green }
:focus::placeholder { color: blue }
</style>

<div id=host tabindex=1></div>

<script>
var host = document.getElementById('host');
var shadow = host.attachShadow({mode: 'closed'});
shadow.innerHTML = `
    <div>shadow</div>
`;

test(() => {
    internals.updateLayoutIgnorePendingStylesheetsAndRunPostLayoutTasks();

    host.focus();

    var div = shadow.querySelector("div");
    assert_equals(internals.styleChangeType(host), "InlineStyleChange");
    assert_equals(internals.styleChangeType(div), "NoStyleChange");
}, "Author shadow tree is not invalidated in presence of user agent shadow tree targeting pseudo elements");

</script>