@Test
public void throwsUnknown() throws Exception {

    try {
        calendarAdapter().fromJson("\"2010-MAY-13\"");
        fail();
    } catch (Throwable e) {
        assertThat(e).isInstanceOf(AssertionError.class)
                .hasMessage("Unsupported date format! Expecting ISO 8601, but found: 2010-MAY-13");
    }
}