### Question:
DecisionTreeChildModel extends AbstractValueModel { @Override public Object getValue() { return d_value; } DecisionTreeChildModel(final DecisionTree tree, final DecisionTreeEdge edge); @Override Object getValue(); @Override void setValue(final Object newValue);  }### Answer:
@Test public void testGetValue() { assertEquals(d_child1, d_model.getValue()); d_tree.replaceChild(d_edge, d_child2); assertEquals(d_child2, d_model.getValue()); d_tree.removeChild(d_child2); assertNull(d_model.getValue()); }