dRegistry2 = new CustomElementRegistry;
    scopedRegistry2.define('f-g', FGElement);
    scopedRegistry2.define('h-i', HIElement);

    const deElement = document.createElement('d-e', {customElementRegistry: scopedRegistry1});
    assert_true(deElement instanceof DEElement);
    assert_equals(deElement.customElementRegistry, scopedRegistry1);
    assert_true(fgElement instanceof FGElement);
    assert_equals(fgElement.customElementRegistry, scopedRegistry2);
    assert_true(hiElement instanceof HIElement);