@Test
public void invokeParamStringDuration() {

    FunctionTestUtil.assertResult(durationFunction.invoke("P2D"), Duration.of(2, ChronoUnit.DAYS));
    FunctionTestUtil.assertResult(durationFunction.invoke("P2DT3H"), Duration.of(2, ChronoUnit.DAYS).plusHours(3));
    FunctionTestUtil.assertResult(
            durationFunction.invoke("P2DT3H28M"),
            Duration.of(2, ChronoUnit.DAYS).plusHours(3).plusMinutes(28));
    FunctionTestUtil.assertResult(
            durationFunction.invoke("P2DT3H28M15S"),
            Duration.of(2, ChronoUnit.DAYS).plusHours(3).plusMinutes(28).plusSeconds(15));
}