@Test
public void testAbsFunctionPeriod() {

    FunctionTestUtil.assertResult(absFunction.invoke(Period.of( 100, 50, 0 ) ),
            Period.of(100, 50, 0));
    FunctionTestUtil.assertResult(absFunction.invoke(Period.of( -100, 50, 0 ) ),
            Period.of(100, -50, 0));
    FunctionTestUtil.assertResult(absFunction.invoke(Period.of( 100, -50, 0 ) ),
            Period.of(100, -50, 0));
    FunctionTestUtil.assertResult(absFunction.invoke(Period.of( -100, -50, 0 ) ),
            Period.of(100, 50, 0));
    FunctionTestUtil.assertResult(absFunction.invoke(Period.of( -1, 30, 0 ) ),
            Period.of(-1, 30, 0));
    FunctionTestUtil.assertResultError(absFunction.invoke((Period) null ),
            InvalidParametersEvent.class);
}