Added unit test case

Author: ajaypaul-ibm

jpa/eclipselink.jpa.testapps/jpa.test.jpql/src/test/java/org/eclipse/persistence/testing/tests/jpa/jpql/advanced/compositepk/JUnitJPQLComplexAggregateTest.java

@@ -24,6 +24,7 @@
 import org.eclipse.persistence.testing.models.jpa.advanced.compositepk.CompositePKTableCreator;
 import org.eclipse.persistence.testing.models.jpa.advanced.compositepk.Cubicle;
 import org.eclipse.persistence.testing.models.jpa.advanced.compositepk.Scientist;
+import org.eclipse.persistence.testing.models.jpa.advanced.compositepk.ScientistPK;
 import org.junit.Assert;
 
 import java.util.Arrays;
@@ -121,4 +122,32 @@ public void complexCountOnJoinedCompositePK() {
         }
     }
 
+    public void testCompositePrimaryKey() {
+        EntityManager em = createEntityManager();
+        try {
+            beginTransaction(em);
+            Scientist scientist = new Scientist();
+            scientist.setFirstName("John");
+            scientist.setLastName("Doe");
+            Cubicle cubicle = new Cubicle();
+            cubicle.setCode("G");
+            cubicle.setScientist(scientist);
+            scientist.setCubicle(cubicle);
+            em.persist(cubicle);
+            em.persist(scientist);
+            em.flush();
+            List<ScientistPK> keys = getEntityManagerFactory().callInTransaction(entityManager -> 
+            entityManager.createQuery(
+            "SELECT ID(THIS) FROM Scientist WHERE firstName = :firstName ORDER BY idNumber",
+            ScientistPK.class
+            )
+            .setParameter("firstName", "John")
+            .getResultList());
+            assertTrue("The result size should be greater than 0", !keys.isEmpty());
+        } finally {
+            rollbackTransaction(em);
+        }
+    }
+    
+
 }