### Question:
IbftHelpers { public static int calculateRequiredValidatorQuorum(final int validatorCount) { return Util.fastDivCeiling(2 * validatorCount, 3); }  static int calculateRequiredValidatorQuorum(final int validatorCount); static long prepareMessageCountForQuorum(final long quorum); static Block createSealedBlock(
      final Block block, final Collection<Signature> commitSeals); static Optional<PreparedCertificate> findLatestPreparedCertificate(
      final Collection<SignedData<RoundChangePayload>> msgs); static final Hash EXPECTED_MIX_HASH; }### Answer:
@Test public void calculateRequiredValidatorQuorum1Validator() { Assertions.assertThat(IbftHelpers.calculateRequiredValidatorQuorum(1)).isEqualTo(1); }
@Test public void calculateRequiredValidatorQuorum2Validator() { Assertions.assertThat(IbftHelpers.calculateRequiredValidatorQuorum(2)).isEqualTo(2); }
@Test public void calculateRequiredValidatorQuorum3Validator() { Assertions.assertThat(IbftHelpers.calculateRequiredValidatorQuorum(3)).isEqualTo(2); }
@Test public void calculateRequiredValidatorQuorum4Validator() { Assertions.assertThat(IbftHelpers.calculateRequiredValidatorQuorum(4)).isEqualTo(3); }
@Test public void calculateRequiredValidatorQuorum5Validator() { Assertions.assertThat(IbftHelpers.calculateRequiredValidatorQuorum(5)).isEqualTo(4); }
@Test public void calculateRequiredValidatorQuorum7Validator() { Assertions.assertThat(IbftHelpers.calculateRequiredValidatorQuorum(7)).isEqualTo(5); }
@Test public void calculateRequiredValidatorQuorum10Validator() { Assertions.assertThat(IbftHelpers.calculateRequiredValidatorQuorum(10)).isEqualTo(7); }
@Test public void calculateRequiredValidatorQuorum15Validator() { Assertions.assertThat(IbftHelpers.calculateRequiredValidatorQuorum(15)).isEqualTo(10); }
@Test public void calculateRequiredValidatorQuorum20Validator() { Assertions.assertThat(IbftHelpers.calculateRequiredValidatorQuorum(20)).isEqualTo(14); }