@Test public void on_completion_should_have_span_in_scope() {

  Span span = tracing.tracer().nextSpan().start();
  Callback delegate =
    (metadata, exception) -> assertThat(currentTraceContext.get()).isSameAs(span.context());
  TracingCallback.create(delegate, span, currentTraceContext)
    .onCompletion(createRecordMetadata(), null);
  assertThat(spans.get(0).finishTimestamp()).isNotZero();
}