### Question:
DecisionNavigatorNestedItemFactory { String getUUID(final Node<View, Edge> node) { final Expression expression = getExpression(node); return expression.getId().getValue(); } @Inject  DecisionNavigatorNestedItemFactory(final SessionManager sessionManager,
                                              final Event<EditExpressionEvent> editExpressionEvent,
                                              final DMNGraphUtils dmnGraphUtils,
                                              final @DMNEditor Supplier<ExpressionEditorDefinitions> expressionEditorDefinitionsSupplier,
                                              final Event<CanvasSelectionEvent> canvasSelectionEvent,
                                              final BoxedExpressionHelper helper); DecisionNavigatorItem makeItem(final Node<View, Edge> node); boolean hasNestedElement(final Node<View, Edge> node);  }### Answer:
@Test public void testGetUUID() { final Expression expression = mock(Expression.class); final Id id = mock(Id.class); final String expectedUUID = "uuid"; when(boxedExpressionHelper.getExpression(node)).thenReturn(expression); when(expression.getId()).thenReturn(id); when(id.getValue()).thenReturn(expectedUUID); final String actualUUID = factory.getUUID(node); assertEquals(expectedUUID, actualUUID); }