### Question:
RenterJdbcGateway implements RenterGateway { @Override public Optional<Renter> findByEmail(final String email) { final List<Renter> renters = jdbcTemplate .query("SELECT * FROM RENT_A_CAR.RENTER WHERE EMAIL = ?", mapper, new Object[]{email}); return Optional.ofNullable(renters.isEmpty() ? null : renters.get(0)); } RenterJdbcGateway(final JdbcTemplate jdbcTemplate); @Override Renter save(final Renter renter); @Override Optional<Renter> findByEmail(final String email);  }### Answer:
@Test void test_findByEmail_noEmail_returnsNoResult() { final Optional<Renter> renterOptional = renterGateway.findByEmail("john.doe@email.com"); Assertions.assertFalse(renterOptional.isPresent()); }