### Question:
ProviderServiceImpl implements ProviderService { @Override public Collection<ProviderKey> getProvidersKey(final ProviderType providerType) { return getProviders(providerType).stream() .map(AbstractHasKeyObject::getKey) .collect(toList()); } ProviderServiceImpl(); @Inject  ProviderServiceImpl(final RuntimeProvisioningServiceBackend runtimeProvisioningService,
                               final ProviderConverterFactory providerConverterFactory); @Override Collection<Provider> getProviders(final ProviderType providerType); @Override Collection<ProviderKey> getProvidersKey(final ProviderType providerType); @Override void createProvider(final ProviderType providerType,
                               final ProviderConfiguration configuration); @Override void deleteProvider(final ProviderKey providerKey); @Override Provider getProvider(final ProviderKey providerKey);  }### Answer:
@Test public void testGetProvidersKey() { Collection<ProviderKey> result = service.getProvidersKey(providerType); assertEquals(providerKeys, result); }