public void groupingChangeWithRemovingAndAddingSameCategory() {
Resource resource = createResource(1);
resource.putValue(TEXT_PROPERTY_1, "category1");
resource.putValue(TEXT_PROPERTY_2, "category1");
underTest.setCategorizer(new ResourceByPropertyMultiCategorizer(
TEXT_PROPERTY_1));
helper.getContainedResources().add(resource);
underTest.setCategorizer(new ResourceByPropertyMultiCategorizer(
TEXT_PROPERTY_2));
assertEquals("category1", getFirstVisualItem().getId());
}