private void assertAccountUpdateConsumers(Set<Account> expectedAccounts, int expectedNumberOfConsumers,
      List<Collection<Account>> accountsInConsumers) throws Exception {
    assertEquals("Wrong number of consumers", expectedNumberOfConsumers, accountsInConsumers.size());
    for (Collection<Account> accounts : accountsInConsumers) {
      assertEquals("Wrong number of updated accounts received by consumers", expectedAccounts.size(), accounts.size());
      for (Account account : accounts) {
        assertTrue("Account update not received by consumers", expectedAccounts.contains(account));
      }
      TestUtils.assertException(UnsupportedOperationException.class,
          () -> accounts.add(InMemoryAccountService.UNKNOWN_ACCOUNT), null);
    }
  }
Asserts the {@link Account}s received by the {@link Consumer} are as expected.
@param expectedAccounts The expected collection of {@link Account}s that should be received by the {@link Consumer}s.
@param expectedNumberOfConsumers The expected number of {@link Consumer}s.
@param accountsInConsumers A list of collection of {@link Account}s, where each collection of {@link Account}s are
                           received by one {@link Consumer}.
ambry-account/src/test/java/com/github/ambry/account/HelixAccountServiceTest.java