adam bien's blog

First you will need to load both: the Bean Validation and EL SPIs. Hibernate Validator is the Reference Implementation (RI) for Bean Validation, and GlassFish implements the EL JSR:

	   <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>5.1.2.Final</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.glassfish</groupId>
            <artifactId>javax.el</artifactId>
            <version>3.0.0</version>
            <scope>test</scope>
        </dependency>

Hibernate Validator requires Expression Language dependency. Without the javax.el dependency you will get the following error:

Caused by: javax.validation.ValidationException: HV000183: Unable to load 'javax.el.ExpressionFactory'. Check that you have the EL dependencies on the classpath
	at org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator.(ResourceBundleMessageInterpolator.java:172)
	at org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator.(ResourceBundleMessageInterpolator.java:118)

Now you are ready to launch your Integration Test:

import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import org.junit.Before;
import org.junit.Test;

public class ValidationTest {

    private Validator validator;

    @Before
    public void init() {

        ValidatorFactory vf = Validation.buildDefaultValidatorFactory();
        this.validator = vf.getValidator();

    }

    @Test
    public void prereqsMet() {
        Workshop validWorkshop = new Workshop(2, 2, true, 3);
        Set<ConstraintViolation<Workshop>> violations = this.validator.validate(validWorkshop);
        assertTrue(violations.isEmpty());
    }  
}

Strictly speaking it is not a unit test, rather an Integration Test. In Unit Test you would like to test the validator logic only, without any dependencies to the SPI.

See you at Java EE Workshops at MUC Airport, especially at the Java EE 7 / Java 8 Testing day!