@Test
  public void dynamicNodeAdditionsTest() throws Exception {
    assumeTrue(!useComposite && !overrideEnabled);

    testHardwareLayout.addNewDataNodes(1);
    Utils.writeJsonObjectToFile(testHardwareLayout.getHardwareLayout().toJSONObject(), hardwareLayoutPath);
    // this triggers a notification.
    helixCluster.upgradeWithNewHardwareLayout(hardwareLayoutPath);
  }
Tests that if an InstanceConfig change notification is triggered with new instances, it is handled gracefully (no
exceptions). When we introduce support for dynamically adding them to the cluster map, this test should be enhanced
to actually verify that the new nodes are added.
@throws Exception
ambry-clustermap/src/test/java/com/github/ambry/clustermap/HelixClusterManagerTest.java