### Question:
MetricsMetadataHandler extends MetadataHandler { @Override public ListSchemasResponse doListSchemaNames(BlockAllocator blockAllocator, ListSchemasRequest listSchemasRequest) { return new ListSchemasResponse(listSchemasRequest.getCatalogName(), Collections.singletonList(SCHEMA_NAME)); } MetricsMetadataHandler(); @VisibleForTesting protected  MetricsMetadataHandler(AmazonCloudWatch metrics,
            EncryptionKeyFactory keyFactory,
            AWSSecretsManager secretsManager,
            AmazonAthena athena,
            String spillBucket,
            String spillPrefix); @Override ListSchemasResponse doListSchemaNames(BlockAllocator blockAllocator, ListSchemasRequest listSchemasRequest); @Override ListTablesResponse doListTables(BlockAllocator blockAllocator, ListTablesRequest listTablesRequest); @Override GetTableResponse doGetTable(BlockAllocator blockAllocator, GetTableRequest getTableRequest); @Override void getPartitions(BlockWriter blockWriter, GetTableLayoutRequest request, QueryStatusChecker queryStatusChecker); @Override GetSplitsResponse doGetSplits(BlockAllocator blockAllocator, GetSplitsRequest getSplitsRequest);  }### Answer:
@Test public void doListSchemaNames() { logger.info("doListSchemas - enter"); ListSchemasRequest req = new ListSchemasRequest(identity, "queryId", "default"); ListSchemasResponse res = handler.doListSchemaNames(allocator, req); logger.info("doListSchemas - {}", res.getSchemas()); assertTrue(res.getSchemas().size() == 1); assertEquals(defaultSchema, res.getSchemas().iterator().next()); logger.info("doListSchemas - exit"); }