final long personId = 42L;
assertEquals(0, getFollowingCount("Follower", userId, personId));
getEntityManager().clear();
sut = new ChangeStreamActivitySubscriptionDbMapper(EntityType.PERSON);
((BaseDomainMapper) sut).setEntityManager(getEntityManager());
sut.execute(new ChangeStreamActivitySubscriptionMapperRequest(userId, personId, true, false));
getEntityManager().clear();
assertEquals(0, getFollowingCount("Follower", userId, personId));