@Test
  void fetch() {
    repository.insert(generator.get().withValue("v1"));
    repository.insert(generator.get().withValue("v1"));
    repository.insert(generator.get().withValue("v2"));

    // exists
    Checkers.check(repository.findAll().exists());
    Checkers.check(repository.find(string.value.is("v1")).exists());
    Checkers.check(repository.find(string.value.is("v2")).exists());
    Checkers.check(!repository.find(string.value.is("v3")).exists());

    // one
    Assertions.assertThrows(NonUniqueResultException.class, () -> repository.findAll().one());
    Assertions.assertThrows(NonUniqueResultException.class, () -> repository.find(string.value.is("v1")).one());
    Assertions.assertThrows(NonUniqueResultException.class, () -> repository.find(string.value.is("v1")).one());
    Assertions.assertThrows(NonUniqueResultException.class, () -> repository.find(string.value.is("v3")).one());
    check(repository.find(string.value.is("v2")).one().value()).is("v2");

    // oneOrNone
    Assertions.assertThrows(NonUniqueResultException.class, () -> repository.findAll().oneOrNone());
    Assertions.assertThrows(NonUniqueResultException.class, () -> repository.find(string.value.is("v1")).oneOrNone());
    check(repository.find(string.value.is("v2")).oneOrNone().get().value()).is("v2");
    check(!repository.find(string.value.is("v3")).oneOrNone().isPresent());
  }
validate {@code one() / oneOrNone() / exists()} methods
criteria/common/test/org/immutables/criteria/typemodel/StringTemplate.java