@Override
	public Map<String, String> apply(ServerWebExchange exchange) {
		StainingRule stainingRule = stainingRuleManager.getStainingRule();

		if (stainingRule == null) {
			return Collections.emptyMap();
		}

		return ruleStainingExecutor.execute(exchange, stainingRule);
	}
@Test
	public void testNoStainingRule() {
		RuleStainingProperties ruleStainingProperties = new RuleStainingProperties();
		ruleStainingProperties.setNamespace(testNamespace);
		ruleStainingProperties.setGroup(testGroup);
		ruleStainingProperties.setFileName(testFileName);

		ConfigFile configFile = Mockito.mock(ConfigFile.class);
		when(configFile.getContent()).thenReturn("");
		when(configFileService.getConfigFile(testNamespace, testGroup, testFileName)).thenReturn(configFile);

		StainingRuleManager stainingRuleManager = new StainingRuleManager(ruleStainingProperties, configFileService);
		RuleStainingExecutor ruleStainingExecutor = new RuleStainingExecutor();
		RuleTrafficStainer ruleTrafficStainer = new RuleTrafficStainer(stainingRuleManager, ruleStainingExecutor);
		Map<String, String> map = ruleTrafficStainer.apply(null);
		assertThat(map).isEmpty();
	}