@Test
public void testRootStart() throws Exception {

    SofaTracerSpanContext sofaTracerSpanContext = SofaTracerSpanContext.rootStart();
    assertEquals(SofaTracer.ROOT_SPAN_ID, sofaTracerSpanContext.getSpanId());
    assertTrue(StringUtils.isBlank(sofaTracerSpanContext.getParentId()));
    assertTrue(!sofaTracerSpanContext.isSampled());
}