Resource resource1 = createResource(TYPE_1, 1);
resource1.putValue(propertyName, 1d);
helper.addToContainedResources(resource1);
final VisualItem visualItem = underTest.getFullVisualItemContainer()
.getVisualItems().getFirstElement();
visualItem.getValue(slot); // caches values
// needs to be done before adding
final double[] result = captureVisualItemNumberSlotValueOnUpdate(visualItem);
Resource resource2 = createResource(TYPE_1, 2);