@Override
  public void assertTag(String name, String expected, BaseSource source) {
    getMetrics(source);
    String cName = canonicalizeMetricName(name);
    assertEquals("Tags should be equal", expected, tags.get(cName));
  }
A helper class that will allow tests to get into hadoop2's metrics2 values.
hbase-hadoop-compat/src/test/java/org/apache/hadoop/hbase/test/MetricsAssertHelperImpl.java