@Before
  public void setUp() throws Exception {
    TEST_UTIL = new HBaseTestingUtil();
  }
Increments with some concurrency against a region to ensure we get the right answer. Test is
parameterized to run the fast and slow path increments; if fast,
HRegion.INCREMENT_FAST_BUT_NARROW_CONSISTENCY_KEY is true.
<p>
There is similar test up in TestAtomicOperation. It does a test where it has 100 threads doing
increments across two column families all on one row and the increments are connected to prove
atomicity on row.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestRegionIncrement.java