@Test
  public void testCreateAccount() throws Exception {
    accountService = mockHelixAccountServiceFactory.getAccountService();
    assertEquals("The number of account in HelixAccountService is incorrect", 0,
        accountService.getAllAccounts().size());
    accountService.updateAccounts(idToRefAccountMap.values());
    assertAccountsInAccountService(idToRefAccountMap.values(), NUM_REF_ACCOUNT, accountService);
  }
Tests creating a number of new {@link Account} through {@link HelixAccountService}, where there is no {@link ZNRecord}
exists on the {@code ZooKeeper}.
ambry-account/src/test/java/com/github/ambry/account/HelixAccountServiceTest.java