innerHTML-setter-default-namespace.xhtml

<?xml version="1.0" encoding="utf-8"?>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>
<body>
<span xmlns="someNamespace" xmlns:html="http://www.w3.org/1999/xhtml">
    <html:span id="target"/>
</span>
<script>
<![CDATA[

test(() => {
    const element = document.getElementById("target");
    element.innerHTML = '<b /><html:b />';
    assert_equals(element.firstChild.prefix, null);
    assert_equals(element.firstChild.namespaceURI, "someNamespace");
    assert_equals(element.lastChild.prefix, 'html');
    assert_equals(element.lastChild.namespaceURI, "http://www.w3.org/1999/xhtml");
}, "Setting innerHTML on a HTML element with a non-HTML namespace as the default namespace");

test(() => {
    const element = document.getElementById("target");
    element.outerHTML = '<b /><html:b />';
    assert_equals(element.firstChild.prefix, null);
    assert_equals(element.firstChild.namespaceURI, "someNamespace");
    assert_equals(element.lastChild.prefix, 'html');
    assert_equals(element.lastChild.namespaceURI, "http://www.w3.org/1999/xhtml");
}, "Setting outerHTML on a HTML element with a non-HTML namespace as the default namespace");

]]>
</script>
</body>
</html>

chromium/third_party/blink/web_tests/external/wpt/html/syntax/parsing-html-fragments/innerHTML-setter-default-namespace.xhtml