@Test
  public void systemHasAlertListenerIsTrueAfterAdding() {
    alertingService.addAlertListener(member, WARNING);

    assertThat(internalDistributedSystem.hasAlertListenerFor(member, WARNING.intLevel())).isTrue();
  }
Integration tests for adding and removing {@code Alert} listeners.
geode-log4j/src/integrationTest/java/org/apache/geode/alerting/log4j/internal/impl/AlertListenerRegistrationIntegrationTest.java