@Test
  public void testBlockContainingKey() throws Exception {
    testBlockContainingKeyInternals(TagUsage.NO_TAG);
    testBlockContainingKeyInternals(TagUsage.ONLY_TAG);
    testBlockContainingKeyInternals(TagUsage.PARTIAL_TAG);
  }
Test {@link HFileScanner#seekTo(Cell)} and its variants.
hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/TestSeekTo.java