@Test public void withSpanInScope() {

  Span current = tracer.newTrace();
  try (SpanInScope ws = tracer.withSpanInScope(current)) {
    assertThat(tracer.currentSpan())
      .isEqualTo(current);
    assertThat(tracer.currentSpanCustomizer())
      .isNotEqualTo(current)
      .isNotEqualTo(NoopSpanCustomizer.INSTANCE);
  }
  // context was cleared
  assertThat(tracer.currentSpan()).isNull();
}