### Question:
FunctionRegistryHolder { public List<String> getFunctionNamesByJar(String jarName) { try (AutoCloseableLock lock = readLock.open()){ Map<String, Queue<String>> functions = jars.get(jarName); return functions == null ? Lists.<String>newArrayList() : Lists.newArrayList(functions.keySet()); } } FunctionRegistryHolder(); long getVersion(); void addJars(Map<String, List<FunctionHolder>> newJars, long version); void removeJar(String jarName); List<String> getAllJarNames(); List<String> getFunctionNamesByJar(String jarName); ListMultimap<String, DrillFuncHolder> getAllFunctionsWithHolders(AtomicLong version); ListMultimap<String, DrillFuncHolder> getAllFunctionsWithHolders(); ListMultimap<String, String> getAllFunctionsWithSignatures(); List<DrillFuncHolder> getHoldersByFunctionName(String functionName, AtomicLong version); List<DrillFuncHolder> getHoldersByFunctionName(String functionName); boolean containsJar(String jarName); int functionsSize(); String getJarNameByFunctionSignature(String functionName, String functionSignature);  }### Answer:
@Test public void testGetFunctionNamesByJar() { ArrayList<String> expectedResult = Lists.newArrayList(); for (FunctionHolder functionHolder : newJars.get(built_in)) { expectedResult.add(functionHolder.getName()); } compareTwoLists(expectedResult, registryHolder.getFunctionNamesByJar(built_in)); }