### Question:
DMNClientDiagramValidator extends ClientDiagramValidator { Consumer<Collection<DiagramElementViolation<RuleViolation>>> getCollectionConsumer(final Diagram diagram, final Consumer<Collection<DiagramElementViolation<RuleViolation>>> resultConsumer) { return diagramElementViolations -> dmnMarshallerService.marshall(diagram, getContentServiceCallback(diagram, resultConsumer, diagramElementViolations)); } protected  DMNClientDiagramValidator(); @Inject  DMNClientDiagramValidator(final DefinitionManager definitionManager,
                                     final RuleManager ruleManager,
                                     final TreeWalkTraverseProcessor treeWalkTraverseProcessor,
                                     final ModelValidator modelValidator,
                                     final ManagedInstance<DomainValidator> validators,
                                     final Caller<DMNDomainValidator> dmnDomainValidator,
                                     final DMNMarshallerService dmnMarshallerService); @Override void validate(final Diagram diagram,
                         final Consumer<Collection<DiagramElementViolation<RuleViolation>>> resultConsumer);  }### Answer:
@Test public void testGetCollectionConsumer() { doReturn(diagramXmlServiceCallback).when(validator).getContentServiceCallback(diagram, violationsConsumer, violations); validator.getCollectionConsumer(diagram, violationsConsumer).accept(violations); verify(dmnMarshallerService).marshall(diagram, diagramXmlServiceCallback); }