public List<String> collectErrorsFromAllNodes() {
    List<String> errors = new ArrayList<>();
    for (T node : mNodeResults.values()) {
      // add all the errors for this node, with the node appended to prefix
      for (String err : node.getErrors()) {
        errors.add(String.format("%s :%s", node.getBaseParameters().mId, err));
      }
    }
    return errors;
  }
@Test
  public void collectErrorFromAllNodesWithNoErrors() {
    // test summary with node and no error
    TestMultipleNodeSummary summary = new TestMultipleNodeSummary();
    summary.addTaskResultWithoutErrors(6);
    List<String> emptyList = summary.collectErrorsFromAllNodes();
    assertTrue(emptyList.isEmpty());
  }