### Question:
SentinelZuulErrorFilter extends ZuulFilter { @Override public Object run() throws ZuulException { RequestContext ctx = RequestContext.getCurrentContext(); Throwable throwable = ctx.getThrowable(); if (throwable != null) { if (!BlockException.isBlockException(throwable)) { SentinelEntryUtils.tryTraceExceptionThenExitFromCurrentContext(throwable); RecordLog.info("[SentinelZuulErrorFilter] Trace error cause", throwable.getCause()); } } return null; } SentinelZuulErrorFilter();  SentinelZuulErrorFilter(int order); @Override String filterType(); @Override boolean shouldFilter(); @Override int filterOrder(); @Override Object run();  }### Answer:
@Test public void testRun() throws Exception { SentinelZuulErrorFilter sentinelZuulErrorFilter = new SentinelZuulErrorFilter(); Object result = sentinelZuulErrorFilter.run(); Assert.assertNull(result); }