@Test
  public void testQuotaRejected() throws Exception {
    // Create a router with QuotaRejectionOperationController for this test.
    router.close();
    Properties properties = getNonBlockingRouterProperties();
    properties.setProperty(RouterConfig.OPERATION_CONTROLLER,
        QuotaRejectingOperationController.class.getCanonicalName());
    VerifiableProperties vProps = new VerifiableProperties(properties);
    RouterConfig routerConfig = new RouterConfig(vProps);
    router = new NonBlockingRouter(routerConfig, new NonBlockingRouterMetrics(clusterMap, routerConfig),
        new MockNetworkClientFactory(vProps, mockSelectorState, MAX_PORTS_PLAIN_TEXT, MAX_PORTS_SSL,
            CHECKOUT_TIMEOUT_MS, serverLayout, mockTime), new LoggingNotificationSystem(), clusterMap, null, null, null,
        new InMemAccountService(false, true), mockTime, MockClusterMap.DEFAULT_PARTITION_CLASS, null);
    testWithQuotaRejection(deleteErrorCodeChecker);
  }
Test for the case when delete operation fails due to quota compliance.
ambry-router/src/test/java/com/github/ambry/router/DeleteManagerTest.java