### Question:
UuidBasedTrackerIdFetcher extends TrackerIdFetcher { @Override public String fetch(Http.Context ctx) { return randomUUID().toString(); }  @Override String fetch(Http.Context ctx);  }### Answer:
@Test public void should_return_uuid() { BDDMockito.given(UUID.randomUUID().toString()).willReturn("123"); Assert.assertEquals(uuidBasedTrackerIdFetcher.fetch(context), "123"); }