@Override
  public String create(UserDto user) {
    UserDto userDto = requireNonNull(user, "User cannot be null");
    return hash(requireNonNull(emptyToNull(userDto.getEmail()), "Email cannot be null"));
  }
@Test
  public void create() {
    String avatar = underTest.create(UserTesting.newUserDto("john", "John", "john@doo.com"));

    assertThat(avatar).isEqualTo("9297bfb538f650da6143b604e82a355d");
  }