@Test
  public void testEmptyNamespaceName() {
    for (String nn : emptyNames) {
      assertThrows(IllegalArgumentException.class,
        () -> TableName.isLegalNamespaceName(Bytes.toBytes(nn)));
    }
  }
Tests for various kinds of TableNames.
hbase-common/src/test/java/org/apache/hadoop/hbase/TestTableName.java