Sometimes you need to test something which uses Bean Validation. For instance, you are using JPA and your entities use Bean Validation. In this case, if you have any implementation of jsr-303 (like hibernate validation), it will run automatically on JPA calls.

In the above case, the test can throw javax.validation.ConstraintViolationException.

Handling JSR-303 Constraint Exceptions

When a ConstraintViolationException has been thrown in a test case, the test will fail (unless it’s excepting that exception). In this case, Junit will show the exception (javax.validation.ConstraintViolationException in this case) and the stack trace.
The problem is that in cases like this, the stack trace will not show intern data from this exception. I will print only the exception itself. Thus, you aren’t able to get the actual validation problems. Without knowing the exact violations, you would need to try guessing it.

Junit Rule

A generic way to solve this, is using a Junit Rule that catches this specific exception e prints its violations.

Use ConstraintViolationRule for this goal. As any Junit Rule, basically you need to add and annotate it in your test classes:

    @Rule
    public ConstraintViolationRule constraintRule = ConstraintViolationRule.getInstance();

The above code will make ConstraintViolationRule catch and print the violations for tests in the same class. If you prefer a different behavior instead of only printing it, just modify it in ConstraintViolationRule class.

This utility is available in ConstraintViolationRule.