static void assertCloseCleanup(NonBlockingRouter router) {
    router.close();
    Assert.assertEquals("No ChunkFiller Thread should be running after the router is closed", 0,
        TestUtils.numThreadsByThisName("ChunkFillerThread"));
    Assert.assertEquals("No RequestResponseHandler should be running after the router is closed", 0,
        TestUtils.numThreadsByThisName("RequestResponseHandlerThread"));
    Assert.assertEquals("All operations should have completed", 0, router.getOperationsCount());
  }
Asserts that expected threads are not running after the router is closed.
ambry-router/src/test/java/com/github/ambry/router/RouterTestHelpers.java