@Override
      public Object call() throws Exception {
        Region r = getCache().getRegion(rName);
        InvalidatePRListener l = (InvalidatePRListener) r.getAttributes().getCacheListeners()[0];
        assertTrue(l.afterRegionInvalidateCalled);
        l.afterRegionInvalidateCalled = false;

        l.callbackArg = "CallBACK";
        return null;
      }
This tests invalidateRegion functionality on partitioned regions
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/PartitionedRegionInvalidateDUnitTest.java