def METHOD_NAME():
    failure = CheckFailure(DummyCheck(), ValueError("Check Failed"), 'Failure Header Message')
    serializer = WidgetSerializer(failure)
    output = serializer.serialize()
    assert_that(
        output,
        all_of(
            instance_of(VBox),
            has_property(
                'children',
                all_of(
                    instance_of(tuple),
                    has_length(3),
                    only_contains(instance_of(HTML)))))
    )
    assert_that(
        output.children[0],
        has_property(
            'value',
            all_of(
                instance_of(str),
                contains_string(failure.header)))
    )
    assert_that(
        output.children[1],
        has_property(
            'value',
            all_of(
                instance_of(str),
                contains_string(t.cast(str,DummyCheck.__doc__))))
    )
    assert_that(
        output.children[2],
        has_property(
            'value',
            all_of(
                instance_of(str),
                contains_string(str(failure.exception))))
    )