@Test
  public void testC2SDeltaPropagationWithOldValueInvalidatedAtServer() throws Exception {
    String key = "DELTA_KEY";
    Integer port1 = server
        .invoke(() -> ClientToServerDeltaDUnitTest.createServerCache(false, false, false, true));
    createClientCache("localhost", port1, false, false, false, null, false, false);

    LocalRegion region = (LocalRegion) cache.getRegion(REGION_NAME);
    region.put(key, new DeltaTestImpl());

    server.invoke(() -> ClientToServerDeltaDUnitTest.doInvalidate(key));
    DeltaTestImpl value = new DeltaTestImpl();
    value.setStr("UPDATED_VALUE");
    region.put(key, value);

    assertTrue(region.getCachePerfStats().getDeltasSent() == 1);
    assertTrue(region.getCachePerfStats().getDeltaFullValuesSent() == 1);
  }
This test ensures that a server sends delta bytes to a client even if that client is not
interested in that event but is getting the event only because the event satisfies a CQ which
the client has registered with the server.
geode-cq/src/distributedTest/java/org/apache/geode/internal/cache/tier/sockets/ClientToServerDeltaDUnitTest.java