@Test public void newChild() {

  TraceContext parent = tracer.newTrace().context();
  assertThat(tracer.newChild(parent))
    .satisfies(c -> {
      assertThat(c.context().traceIdString()).isEqualTo(parent.traceIdString());
      assertThat(c.context().parentIdString()).isEqualTo(parent.spanIdString());
    })
    .isInstanceOf(RealSpan.class);
}