### Question:
OperatorGraphView { public Collection<OperatorView> getOperators() { return all().collect(Collectors.toList()); } OperatorGraphView(OperatorGraphAttribute graph);  OperatorGraphView(PlanAttribute plan);   OperatorGraphView(Node entity); Node getRoot(); Collection<OperatorView> getOperators(); Collection<OperatorView> getOperators(OperatorKind kind); Map<String, OperatorView> getOperatorMap(OperatorKind kind);  }### Answer:
@Test public void simple() { Node root = new Node(); OperatorGraphView view = new OperatorGraphView(new OperatorGraphAttribute(root)); assertThat(view.getOperators(), is(empty())); }