t instance = document.createElement(elementName, { is: element.name });
    // source element as a child of a picture element, before the img element
    parentElement.prepend(instance);
    setAttributes(instance);
    instance[jsAttributeName] = validValue1;

    assert_array_equals(
      element.takeLog().types(),
      ['constructed', 'connected', 'attributeChanged']
    );
    instance[jsAttributeName] = validValue2;
    let logEntries = element.takeLog();
    assert_array_equals(logEntries.types(), [