The test as implemented is not deterministic which results in  BF-36269. As described this test is supposed to verify that even when completion callback passed to InitialSyncer c'tor throws the exception, the initial syncer can still shutdown gracefully. However as mentioned here,  there is a valid scenario in which completion callback is not called at all and in current implementation there is no way to prevent this scenario deterministically. That means, that test can't guarantee its own test case to happen. Since it also causes a sporadic build failure I suggest that the test should be removed.