### Question:
GetEntityVersionsCommand extends AbstractRestCommand { @Override public String run() { LOGGER.debug("run: entity={}", entity); Error.reset(); Error.push(getClass().getSimpleName()); try { VersionInfo[] versions = getMetadata().getEntityVersions(entity); ArrayNode arr = NODE_FACTORY.arrayNode(); for (VersionInfo x : versions) { ObjectNode obj = NODE_FACTORY.objectNode(); obj.put("version", x.getValue()); obj.put("changelog", x.getChangelog()); ArrayNode ev = NODE_FACTORY.arrayNode(); if (x.getExtendsVersions() != null) { for (String v : x.getExtendsVersions()) { ev.add(NODE_FACTORY.textNode(v)); } } obj.set("extendsVersions", ev); obj.put("status", MetadataParser.toString(x.getStatus())); obj.put("defaultVersion", x.isDefault()); arr.add(obj); } return arr.toString(); } catch (Error e) { return e.toString(); } catch (Exception e) { LOGGER.error("Failure: {}", e); return Error.get(RestMetadataConstants.ERR_REST_ERROR, e.toString()).toString(); } } GetEntityVersionsCommand(String entity);  GetEntityVersionsCommand(Metadata metadata, String entity); @Override String run();  }### Answer:
@Test public void execute() { GetEntityVersionsCommand command = new GetEntityVersionsCommand(metadata, null); String output = command.run(); Assert.assertNotNull(output); }