### Question:
VFSRuntimeRegistry extends InMemoryRuntimeRegistry { @PostConstruct protected void init() { initializeRegistryRoot(); initializeRegistry(); } VFSRuntimeRegistry(); @Inject  VFSRuntimeRegistry(final VFSRegistryHelper registryHelper); @Override void registerProvider(final Provider provider); @Override void deregisterProvider(final Provider provider); @Override void deregisterProvider(final String providerId); @Override void registerRuntime(final Runtime runtime); @Override void deregisterRuntime(final RuntimeId runtimeId);  }### Answer:
@Test public void testInit() throws Exception { providers = new ArrayList<>(); providers.addAll(mockProviderListSPI(providerType, ELEMENTS_COUNT)); runtimes = new ArrayList<>(); runtimes.addAll(mockRuntimeList(providerId, "", ELEMENTS_COUNT)); when(registryHelper.readEntries(registryRoot, VFSRegistryHelper.BySuffixFilter.newFilter(PROVIDER_SUFFIX))).thenReturn(providers); when(registryHelper.readEntries(registryRoot, VFSRegistryHelper.BySuffixFilter.newFilter(RUNTIME_SUFFIX))).thenReturn(runtimes); ((VFSRuntimeRegistry) runtimeRegistry).init(); verify(registryHelper, times(2)).ensureDirectory(RUNTIME_REGISTRY_PATH); verify(registryHelper, times(2)).readEntries(registryRoot, VFSRegistryHelper.BySuffixFilter.newFilter(PROVIDER_SUFFIX)); verify(registryHelper, times(2)).readEntries(registryRoot, VFSRegistryHelper.BySuffixFilter.newFilter(RUNTIME_SUFFIX)); for (Object provider : providers) { verifyProviderIsRegistered((Provider) provider); } for (Object runtime : runtimes) { verifyRuntimeIsRegistered((Runtime) runtime); } }