### Question:
CheckClientSelectFieldsStateValidator implements ConstraintValidator<CheckClientSelect,
        ClientSelect>, ValidationErrorDescriptorBuilder { @Override public ErrorDescriptor build(ConstraintViolation violation) { return QUERY_SELECT_ILLEGAL_FIELDS_STATE.createDescriptor(); }  @Override void initialize(CheckClientSelect constraintAnnotation); @Override boolean isValid(ClientSelect value, ConstraintValidatorContext context); @Override ErrorDescriptor build(ConstraintViolation violation);  }### Answer:
@Test public void build_success() { ConstraintViolation violation = mock(ConstraintViolation.class); ErrorDescriptor errorDescriptor = validator.build(violation); assertEquals(new ErrorDescriptor().setErrorCode(QUERY_SELECT_ILLEGAL_FIELDS_STATE), errorDescriptor); }