Spring Boot test entity field validation with custom validation - spring-boot

Question

Setup:
Spring Boot 2.3.3 (spring-boot-starter-validation)
JUnit 5 Jupiter
Lombok
Entity fields can be annotated with simple javax.validation constraints like #Positive.
#Entity
#Data
#Builder
public class Person {
#Id
#GeneratedValue
private long id;
#Column
#Positive(message="not positive")
private int age;
}
This can be tested quite easily:
public class PersonTest {
private Validator validator;
#BeforeEach
public void before() {
validator = Validation.buildDefaultValidatorFactory().getValidator();
}
#Test
public void invalid_becauseNegativeAge() {
Person uut = Person.builder().age(-1).build();
Set<ConstraintViolation<Person>> actual = validator.validate(uut);
assertThat(actual.iterator().next().getMessage()).isEqualTo("not positive");
}
}
Now I add a custom validator to Person:
#Entity
#Data
#Builder
public class Person {
#Id
#GeneratedValue
private long id;
#Column
#Positive(message="not old enough")
private int age;
#ComplexValueConstraint
private String complexValue;
}
Custom annotation:
#Target({ ElementType.FIELD })
#Retention(RetentionPolicy.RUNTIME)
#Constraint(validatedBy = ComplexValueValidator.class)
public #interface ComplexValueConstraint {
String message() default "too simple";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
Custom validator:
class ComplexValueValidator implements ConstraintValidator<ComplexValueConstraint, Person> {
#Override
public boolean isValid(final Person person, final ConstraintValidatorContext context) {
String complexValue = person.getComplexValue();
if (complexValue.length() < 5) {
return false;
}
return true;
}
}
Now, my test from above fails with a
javax.validation.UnexpectedTypeException: HV000030: No validator could be found for constraint 'ComplexValueConstraint' validating type 'java.lang.String'. Check configuration for 'complexValue'
How can I make this test to work again? I know I could test the validator in isolation, but then my simple annotations like #Positive would remain untested.
Is it because I create the validator in the test class manually? #Autowired won't work somehow.

Answer 1

You are declaring that ComplexValueValidator validates objects of type Person:
ComplexValueValidator implements ConstraintValidator<ComplexValueConstraint, Person>
but the annotation is applied to a field of type String instead of a field of type Person:
#ComplexValueConstraint
private String complexValue;
Hence the message that the constraint can not be applied to a java.lang.String.
Try changing complexValue to be of type Person instead of type String.