css/css-font-loading/fontfaceset-add-css-connected.html

<!DOCTYPE html>
<meta charset="utf-8">
<link rel="author" title="Myles C. Maxfield" href="mmaxfield@apple.com">
<link rel="help" href="https://drafts.csswg.org/css-font-loading-3/#dom-fontfaceset-add">
<meta name="assert" content="Ensure that calling add() with a CSS-connected FontFace throws." />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
@font-face {
    font-family: "WebFont";
    src: url("resources/Rochester.otf") format("opentype");
}
</style>
<script>
test(function(t) {
    let font = document.fonts.keys().next().value;
    let fontFaceSet = new FontFaceSet([]);
    assert_equals(fontFaceSet.size, 0);
    assert_throws_dom("InvalidModificationError", function() { fontFaceSet.add(font); });
    assert_equals(fontFaceSet.size, 0);
    let newFont = new FontFace("MyFont", "url('resources/Rochester.otf')");
    fontFaceSet.add(newFont);
    assert_equals(fontFaceSet.size, 1);
    fontFaceSet.add(newFont);
    assert_equals(fontFaceSet.size, 1);
});
</script>
</html>