MDCScopeManager implements ScopeManager { @Override public Span activeSpan() { return wrappedScopeManager.activeSpan(); } private  MDCScopeManager(Builder builder); @Override Scope activate(Span span); @Override Span activeSpan();  }
@Test public void testActiveSpan() { Span mockSpan = Mockito.mock(JaegerSpan.class); try (Scope scope = defaultTracer.activateSpan(mockSpan)) { assertEquals(mockSpan, defaultTracer.activeSpan()); } }