@Test
public void invokeNull() {

    FunctionTestUtil.assertResultError(numberFunction.invoke(null, null, null), InvalidParametersEvent.class);
    FunctionTestUtil.assertResultError(numberFunction.invoke(null, " ", null), InvalidParametersEvent.class);
    FunctionTestUtil.assertResultError(numberFunction.invoke(null, null, "."), InvalidParametersEvent.class);
    FunctionTestUtil.assertResultError(numberFunction.invoke(null, " ", "."), InvalidParametersEvent.class);
}