fix: Added test for many-2- many query using both sides of the relationship

Author: igdianov

graphql-jpa-query-example-model-starwars/src/main/java/com/introproventures/graphql/jpa/query/schema/model/starwars/Character.java

@@ -30,6 +30,7 @@
 import javax.persistence.OrderBy;
 
 import com.introproventures.graphql.jpa.query.annotation.GraphQLDescription;
+
 import lombok.EqualsAndHashCode;
 import lombok.Getter;
 import lombok.Setter;
@@ -40,7 +41,7 @@
 @Getter
 @Setter
 @ToString
-@EqualsAndHashCode(exclude={"appearsIn","friends"}) // Fixes NPE in Hibernate when initializing loaded collections #1
+@EqualsAndHashCode(exclude={"appearsIn","friends", "friendsOf"}) // Fixes NPE in Hibernate when initializing loaded collections #1
 public abstract class Character {
 
     @Id
@@ -58,6 +59,10 @@ public abstract class Character {
     @OrderBy("name ASC")
     Set<Character> friends; 
 
+    @ManyToMany(fetch=FetchType.LAZY, mappedBy = "friends")
+    @OrderBy("name ASC")
+    Set<Character> friendsOf;     
+    
     @GraphQLDescription("What Star Wars episodes does this character appear in")
     @ElementCollection(targetClass = Episode.class, fetch=FetchType.LAZY)
     @Enumerated(EnumType.ORDINAL)

graphql-jpa-query-schema/src/test/java/com/introproventures/graphql/jpa/query/schema/StarwarsQueryExecutorTests.java

@@ -39,6 +39,8 @@
 
 import com.introproventures.graphql.jpa.query.schema.impl.GraphQLJpaExecutor;
 import com.introproventures.graphql.jpa.query.schema.impl.GraphQLJpaSchemaBuilder;
+import com.introproventures.graphql.jpa.query.schema.model.starwars.Character;
+import com.introproventures.graphql.jpa.query.schema.model.starwars.Droid;
 
 @RunWith(SpringRunner.class)
 @SpringBootTest
@@ -86,6 +88,41 @@ public void JPASampleTester() {
         assertThat(result).isNotEmpty();
         assertThat(result).hasSize(13);
     }
+    
+    @Test
+    @Transactional
+    public void queryManyToManyTester() {
+        // given:
+        Query query = em.createQuery("select distinct droid from Droid as droid "
+                                   + "left join fetch droid.friends as generatedAlias0 "
+                                   + "inner join fetch generatedAlias0.friendsOf as generatedAlias1 "
+                                   + "where generatedAlias1.name='Luke Skywalker' "
+                                   + "order by droid.id asc");
+
+        query.setHint("hibernate.query.passDistinctThrough", false);
+
+        // when:
+        List<Droid> result = query.getResultList();
+
+        // then:
+        assertThat(result).hasSize(2);
+
+        assertThat(result.get(0).getName()).isEqualTo("C-3PO");
+        assertThat(result.get(0).getFriends()).hasSize(3);
+        assertThat(result.get(0).getFriends()).extracting(Character::getName)
+                                              .containsOnly("Han Solo", "Leia Organa", "R2-D2"); 
+        assertThat(result.get(0).getFriends()).flatExtracting(Character::getFriendsOf)
+                                              .extracting(Character::getName)
+                                              .containsOnly("Luke Skywalker");
+        
+        assertThat(result.get(1).getName()).isEqualTo("R2-D2");
+        assertThat(result.get(1).getFriends()).hasSize(2);
+        assertThat(result.get(1).getFriends()).extracting(Character::getName)
+                                              .containsOnly("Han Solo", "Leia Organa");
+        assertThat(result.get(1).getFriends()).flatExtracting(Character::getFriendsOf)
+                                              .extracting(Character::getName)
+                                              .containsOnly("Luke Skywalker");
+    }
 
     @Test
     public void getsNamesOfAllDroids() {