### Question:
SchemaMetrics { public static String generateSchemaMetricsPrefix(String tableName, final String cfName) { tableName = getEffectiveTableName(tableName); String schemaMetricPrefix = tableName.equals(TOTAL_KEY) ? "" : TABLE_PREFIX + tableName + "."; schemaMetricPrefix += cfName.equals(TOTAL_KEY) ? "" : CF_PREFIX + cfName + "."; return schemaMetricPrefix; } private  SchemaMetrics(final String tableName, final String cfName); static SchemaMetrics getInstance(String tableName, String cfName); String getBlockMetricName(BlockCategory blockCategory,
      boolean isCompaction, BlockMetricType metricType); String getBloomMetricName(boolean isInBloom); void accumulateStoreMetric(final Map<String, MutableDouble> tmpMap,
      StoreMetricType storeMetricType, double val); String getStoreMetricName(StoreMetricType storeMetricType); String getStoreMetricNameMax(StoreMetricType storeMetricType); void updatePersistentStoreMetric(StoreMetricType storeMetricType,
      long value); void updateOnCacheHit(BlockCategory blockCategory,
      boolean isCompaction); void updateOnCacheHit(BlockCategory blockCategory,
      boolean isCompaction, long count); void flushMetrics(); void updateOnCacheMiss(BlockCategory blockCategory,
      boolean isCompaction, long timeMs); void addToCacheSize(BlockCategory category, long cacheSizeDelta); void updateOnCachePutOrEvict(BlockCategory blockCategory,
      long cacheSizeDelta, boolean isEviction); void updateBloomMetrics(boolean isInBloom); static void configureGlobally(Configuration conf); static String generateSchemaMetricsPrefix(String tableName,
      final String cfName); static String generateSchemaMetricsPrefix(byte[] tableName,
      byte[] cfName); static String generateSchemaMetricsPrefix(String tableName,
      Set<byte[]> families); static Map<String, Long> getMetricsSnapshot(); static long getLong(Map<String, Long> m, String k); static Map<String, Long> diffMetrics(Map<String, Long> a,
      Map<String, Long> b); static void validateMetricChanges(Map<String, Long> oldMetrics); static SchemaMetrics getUnknownInstanceForTest(); static void setUseTableNameInTest(final boolean useTableNameNew); static String formatMetrics(Map<String, Long> metrics); static final String UNKNOWN; static final String TABLE_PREFIX; static final String CF_PREFIX; static final String BLOCK_TYPE_PREFIX; static final String REGION_PREFIX; static final String CF_UNKNOWN_PREFIX; static final String CF_BAD_FAMILY_PREFIX; static final boolean NO_COMPACTION; static final String METRIC_GETSIZE; static final String METRIC_NEXTSIZE; static final String TOTAL_KEY; static final SchemaMetrics ALL_SCHEMA_METRICS; }### Answer:
@Test public void testGenerateSchemaMetricsPrefix() { String tableName = "table1"; int numCF = 3; StringBuilder expected = new StringBuilder(); if (useTableName) { expected.append("tbl."); expected.append(tableName); expected.append("."); } expected.append("cf."); Set<byte[]> families = new HashSet<byte[]>(); for (int i = 1; i <= numCF; i++) { String cf = "cf" + i; families.add(Bytes.toBytes(cf)); expected.append(cf); if (i == numCF) { expected.append("."); } else { expected.append("~"); } } String result = SchemaMetrics.generateSchemaMetricsPrefix(tableName, families); assertEquals(expected.toString(), result); }