JAVA-4: renamed to hibernate-annotations, moved couple of articles

persistence-modules/hibernate5-annotations/README.md

@@ -1,10 +1,10 @@
-## Hibernate 5
+## Hibernate Annotations
 
-This module contains articles about Hibernate 5.
+This module contains articles about Hibernate Annotations.
 
 ### Relevant Articles:
 - [Custom Types in Hibernate and the @Type Annotation](https://www.baeldung.com/hibernate-custom-types)
-- [@Immutable in Hibernate](http://www.baeldung.com/hibernate-immutable)
 - [@JoinColumn Annotation Explained](https://www.baeldung.com/jpa-join-column)
 - [Difference Between @JoinColumn and mappedBy](https://www.baeldung.com/jpa-joincolumn-vs-mappedby)
-
+- [Hibernate One to Many Annotation Tutorial](http://www.baeldung.com/hibernate-one-to-many)
+- [Hibernate @WhereJoinTable Annotation](https://www.baeldung.com/hibernate-wherejointable)

persistence-modules/hibernate5-annotations/src/main/java/com/baeldung/hibernate/oneToMany/config/HibernateAnnotationUtil.java

@@ -0,0 +1,34 @@
+package com.baeldung.hibernate.oneToMany.config;
+
+import org.hibernate.SessionFactory;
+import org.hibernate.boot.Metadata;
+import org.hibernate.boot.MetadataSources;
+import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.service.ServiceRegistry;
+
+public class HibernateAnnotationUtil {
+
+    private static SessionFactory sessionFactory;
+
+    private static SessionFactory buildSessionFactory() {
+        try {
+            // Create the SessionFactory from hibernate-annotation.cfg.xml
+            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().configure("hibernate-annotation.cfg.xml").build();
+            Metadata metadata = new MetadataSources(serviceRegistry).getMetadataBuilder().build();
+            SessionFactory sessionFactory = metadata.getSessionFactoryBuilder().build();
+
+            return sessionFactory;
+
+        } catch (Throwable ex) {
+            System.err.println("Initial SessionFactory creation failed." + ex);
+            ex.printStackTrace();
+            throw new ExceptionInInitializerError(ex);
+        }
+    }
+
+    public static SessionFactory getSessionFactory() {
+        if (sessionFactory == null)
+            sessionFactory = buildSessionFactory();
+        return sessionFactory;
+    }
+}

persistence-modules/hibernate5-annotations/src/main/java/com/baeldung/hibernate/oneToMany/main/HibernateManyisOwningSide.java

@@ -0,0 +1,71 @@
+package com.baeldung.hibernate.oneToMany.main;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.Transaction;
+
+import com.baeldung.hibernate.oneToMany.config.HibernateAnnotationUtil;
+import com.baeldung.hibernate.oneToMany.model.Cart;
+import com.baeldung.hibernate.oneToMany.model.Items;
+import com.baeldung.hibernate.oneToMany.model.ItemsOIO;
+
+public class HibernateManyisOwningSide {
+    public static void main(String[] args) {
+
+        Cart cart = new Cart();
+        Cart cart2 = new Cart();
+
+        Items item1 = new Items(cart);
+        Items item2 = new Items(cart2);
+        Set<Items> itemsSet = new HashSet<Items>();
+        itemsSet.add(item1);
+        itemsSet.add(item2);
+
+        cart.setItems(itemsSet);
+
+        
+        
+        SessionFactory sessionFactory = null;
+        Session session = null;
+        Transaction tx = null;
+        try {
+            // Get Session
+            sessionFactory = HibernateAnnotationUtil.getSessionFactory();
+            session = sessionFactory.getCurrentSession();
+            System.out.println("Session created");
+            // start transaction
+            tx = session.beginTransaction();
+            // Save the Model object
+            session.save(cart);
+            session.save(cart2);
+            session.save(item1);
+            session.save(item2);
+            // Commit transaction
+            tx.commit();
+            session = sessionFactory.getCurrentSession();
+            tx = session.beginTransaction();
+
+            item1 = (Items) session.get(Items.class, new Long(1));
+            item2 = (Items) session.get(Items.class, new Long(2));
+            tx.commit();
+            
+         
+            System.out.println("item1 ID=" + item1.getId() + ", Foreign Key CartOIO ID=" + item1.getCart()
+                .getId());
+            System.out.println("item2 ID=" + item2.getId() + ", Foreign Key CartOIO ID=" + item2.getCart()
+                .getId());
+
+        } catch (Exception e) {
+            System.out.println("Exception occured. " + e.getMessage());
+            e.printStackTrace();
+        } finally {
+            if (!sessionFactory.isClosed()) {
+                System.out.println("Closing SessionFactory");
+                sessionFactory.close();
+            }
+        }
+    }
+}

persistence-modules/hibernate5-annotations/src/main/java/com/baeldung/hibernate/oneToMany/main/HibernateOneToManyAnnotationMain.java

@@ -0,0 +1,60 @@
+package com.baeldung.hibernate.oneToMany.main;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.Transaction;
+
+import com.baeldung.hibernate.oneToMany.config.HibernateAnnotationUtil;
+import com.baeldung.hibernate.oneToMany.model.Cart;
+import com.baeldung.hibernate.oneToMany.model.Items;
+
+public class HibernateOneToManyAnnotationMain {
+
+    public static void main(String[] args) {
+
+        Cart cart = new Cart();
+
+        Items item1 = new Items(cart);
+        Items item2 = new Items(cart);
+        Set<Items> itemsSet = new HashSet<Items>();
+        itemsSet.add(item1);
+        itemsSet.add(item2);
+
+        cart.setItems(itemsSet);
+        
+
+        SessionFactory sessionFactory = null;
+        Session session = null;
+        Transaction tx = null;
+        try {
+            // Get Session
+            sessionFactory = HibernateAnnotationUtil.getSessionFactory();
+            session = sessionFactory.getCurrentSession();
+            System.out.println("Session created");
+            // start transaction
+            tx = session.beginTransaction();
+            // Save the Model object
+            session.save(cart);
+            session.save(item1);
+            session.save(item2);
+            // Commit transaction
+            tx.commit();
+            System.out.println("Cart ID=" + cart.getId());
+            System.out.println("item1 ID=" + item1.getId() + ", Foreign Key Cart ID=" + item1.getCart().getId());
+            System.out.println("item2 ID=" + item2.getId() + ", Foreign Key Cart ID=" + item1.getCart().getId());
+
+        } catch (Exception e) {
+            System.out.println("Exception occured. " + e.getMessage());
+            e.printStackTrace();
+        } finally {
+            if (!sessionFactory.isClosed()) {
+                System.out.println("Closing SessionFactory");
+                sessionFactory.close();
+            }
+        }
+    }
+
+}

persistence-modules/hibernate5-annotations/src/main/java/com/baeldung/hibernate/oneToMany/main/HibernateOneisOwningSide.java

@@ -0,0 +1,67 @@
+package com.baeldung.hibernate.oneToMany.main;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.Transaction;
+
+import com.baeldung.hibernate.oneToMany.config.HibernateAnnotationUtil;
+import com.baeldung.hibernate.oneToMany.model.CartOIO;
+import com.baeldung.hibernate.oneToMany.model.ItemsOIO;
+
+public class HibernateOneisOwningSide {
+    public static void main(String[] args) {
+
+        CartOIO cart = new CartOIO();
+        CartOIO cart2 = new CartOIO();
+
+        ItemsOIO item1 = new ItemsOIO(cart);
+        ItemsOIO item2 = new ItemsOIO(cart2);
+        Set<ItemsOIO> itemsSet = new HashSet<ItemsOIO>();
+        itemsSet.add(item1);
+        itemsSet.add(item2);
+
+        cart.setItems(itemsSet);
+
+        SessionFactory sessionFactory = null;
+        Session session = null;
+        Transaction tx = null;
+        try {
+            // Get Session
+            sessionFactory = HibernateAnnotationUtil.getSessionFactory();
+            session = sessionFactory.getCurrentSession();
+            System.out.println("Session created");
+            // start transaction
+            tx = session.beginTransaction();
+            // Save the Model object
+            session.save(cart);
+            session.save(cart2);
+            session.save(item1);
+            session.save(item2);
+            // Commit transaction
+            tx.commit();
+
+            session = sessionFactory.getCurrentSession();
+            tx = session.beginTransaction();
+            item1 = (ItemsOIO) session.get(ItemsOIO.class, new Long(1));
+            item2 = (ItemsOIO) session.get(ItemsOIO.class, new Long(2));
+            tx.commit();
+
+            System.out.println("item1 ID=" + item1.getId() + ", Foreign Key CartOIO ID=" + item1.getCartOIO()
+                .getId());
+            System.out.println("item2 ID=" + item2.getId() + ", Foreign Key CartOIO ID=" + item2.getCartOIO()
+                .getId());
+
+        } catch (Exception e) {
+            System.out.println("Exception occured. " + e.getMessage());
+            e.printStackTrace();
+        } finally {
+            if (!sessionFactory.isClosed()) {
+                System.out.println("Closing SessionFactory");
+                sessionFactory.close();
+            }
+        }
+    }
+}

persistence-modules/hibernate5-annotations/src/main/java/com/baeldung/hibernate/oneToMany/model/Cart.java

@@ -0,0 +1,43 @@
+package com.baeldung.hibernate.oneToMany.model;
+
+import java.util.Set;
+
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.OneToMany;
+import javax.persistence.Table;
+
+@Entity
+@Table(name = "CART")
+public class Cart {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    @Column(name = "cart_id")
+    private long id;
+
+
+    @OneToMany(mappedBy = "cart")
+    private Set<Items> items;
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+
+    public Set<Items> getItems() {
+        return items;
+    }
+
+    public void setItems(Set<Items> items) {
+        this.items = items;
+    }
+
+}

persistence-modules/hibernate5-annotations/src/main/java/com/baeldung/hibernate/oneToMany/model/CartOIO.java

@@ -0,0 +1,42 @@
+package com.baeldung.hibernate.oneToMany.model;
+
+import java.util.Set;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.JoinColumn;
+import javax.persistence.OneToMany;
+import javax.persistence.Table;
+
+
+
+@Entity
+@Table(name = "CARTOIO")
+public class CartOIO {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private long id;
+
+    @OneToMany
+    @JoinColumn(name = "cart_id") // we need to duplicate the physical information
+    private Set<ItemsOIO> items;
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public Set<ItemsOIO> getItems() {
+        return items;
+    }
+
+    public void setItems(Set<ItemsOIO> items) {
+        this.items = items;
+    }
+
+}

persistence-modules/hibernate5-annotations/src/main/java/com/baeldung/hibernate/oneToMany/model/Items.java

@@ -0,0 +1,50 @@
+package com.baeldung.hibernate.oneToMany.model;
+
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.JoinColumn;
+import javax.persistence.ManyToOne;
+import javax.persistence.Table;
+
+@Entity
+@Table(name = "ITEMS")
+public class Items {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    @Column(name = "id")
+    private long id;
+
+
+    @ManyToOne
+    @JoinColumn(name = "cart_id", nullable = false)
+    private Cart cart;
+
+    // Hibernate requires no-args constructor
+    public Items() {
+    }
+
+    public Items(Cart c) {
+        this.cart = c;
+    }
+
+    public Cart getCart() {
+        return cart;
+    }
+
+    public void setCart(Cart cart) {
+        this.cart = cart;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+}

persistence-modules/hibernate5-annotations/src/main/java/com/baeldung/hibernate/oneToMany/model/ItemsOIO.java

@@ -0,0 +1,47 @@
+package com.baeldung.hibernate.oneToMany.model;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.JoinColumn;
+import javax.persistence.ManyToOne;
+import javax.persistence.Table;
+
+@Entity
+@Table(name = "ITEMSOIO")
+public class ItemsOIO {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private long id;
+
+    @ManyToOne
+    @JoinColumn(name = "cart_id", insertable = false, updatable = false)
+    private CartOIO cart;
+
+    // Hibernate requires no-args constructor
+    public ItemsOIO() {
+    }
+
+    public ItemsOIO(CartOIO c) {
+        this.cart = c;
+    }
+
+    public CartOIO getCartOIO() {
+        return cart;
+    }
+
+    public void setCartOIO(CartOIO cart) {
+        this.cart = cart;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+}

persistence-modules/hibernate5-annotations/src/main/java/com/baeldung/hibernate/wherejointable/Group.java

@@ -0,0 +1,56 @@
+package com.baeldung.hibernate.wherejointable;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.ManyToMany;
+
+@Entity(name = "e_group")
+public class Group {
+
+    @Id
+    @GeneratedValue
+    private Long id;
+
+    private String name;
+
+    @ManyToMany(mappedBy = "groups")
+    private List<User> users = new ArrayList<>();
+
+    public Group(String name) {
+        this.name = name;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public List<User> getUsers() {
+        return users;
+    }
+
+    public void setUsers(List<User> users) {
+        this.users = users;
+    }
+
+    @Override
+    public String toString() {
+        return "Group [name=" + name + "]";
+    }
+
+}

persistence-modules/hibernate5-annotations/src/main/java/com/baeldung/hibernate/wherejointable/User.java

@@ -0,0 +1,74 @@
+package com.baeldung.hibernate.wherejointable;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.JoinColumn;
+import javax.persistence.JoinTable;
+import javax.persistence.ManyToMany;
+
+import org.hibernate.annotations.WhereJoinTable;
+
+@Entity
+public class User {
+
+    @Id
+    @GeneratedValue
+    private Long id;
+
+    private String name;
+
+    @ManyToMany
+    @JoinTable(name = "r_user_group", joinColumns = @JoinColumn(name = "user_id"), inverseJoinColumns = @JoinColumn(name = "group_id"))
+    private List<Group> groups = new ArrayList<>();
+
+    @WhereJoinTable(clause = "role='MODERATOR'")
+    @ManyToMany
+    @JoinTable(name = "r_user_group", joinColumns = @JoinColumn(name = "user_id"), inverseJoinColumns = @JoinColumn(name = "group_id"))
+    private List<Group> moderatorGroups = new ArrayList<>();
+
+    public User(String name) {
+        this.name = name;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public List<Group> getGroups() {
+        return groups;
+    }
+
+    public void setGroups(List<Group> groups) {
+        this.groups = groups;
+    }
+
+    public void setModeratorGroups(List<Group> moderatorGroups) {
+        this.moderatorGroups = moderatorGroups;
+    }
+
+    public List<Group> getModeratorGroups() {
+        return moderatorGroups;
+    }
+
+    @Override
+    public String toString() {
+        return "User [name=" + name + "]";
+    }
+
+}

persistence-modules/hibernate5-annotations/src/main/java/com/baeldung/hibernate/wherejointable/UserGroupRelation.java

@@ -0,0 +1,31 @@
+package com.baeldung.hibernate.wherejointable;
+
+import java.io.Serializable;
+
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.EnumType;
+import javax.persistence.Enumerated;
+import javax.persistence.Id;
+
+@Entity(name = "r_user_group")
+public class UserGroupRelation implements Serializable {
+
+    @Id
+    @Column(name = "user_id", insertable = false, updatable = false)
+    private final Long userId;
+
+    @Id
+    @Column(name = "group_id", insertable = false, updatable = false)
+    private final Long groupId;
+
+    @Enumerated(EnumType.STRING)
+    private final UserGroupRole role;
+
+    public UserGroupRelation(Long userId, Long groupId, UserGroupRole role) {
+        this.userId = userId;
+        this.groupId = groupId;
+        this.role = role;
+    }
+
+}

persistence-modules/hibernate5-annotations/src/main/java/com/baeldung/hibernate/wherejointable/UserGroupRole.java

@@ -0,0 +1,7 @@
+package com.baeldung.hibernate.wherejointable;
+
+public enum UserGroupRole {
+
+    MEMBER, MODERATOR
+
+}

persistence-modules/hibernate5-annotations/src/test/java/com/baeldung/hibernate/oneToMany/main/HibernateOneToManyAnnotationMainIntegrationTest.java

@@ -0,0 +1,95 @@
+package com.baeldung.hibernate.oneToMany.main;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.cfg.Configuration;
+import org.hibernate.dialect.H2Dialect;
+import org.hibernate.service.ServiceRegistry;
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import com.baeldung.hibernate.oneToMany.model.Cart;
+import com.baeldung.hibernate.oneToMany.model.Items;
+
+public class HibernateOneToManyAnnotationMainIntegrationTest {
+
+	private static SessionFactory sessionFactory;
+
+	private Session session;
+
+	public HibernateOneToManyAnnotationMainIntegrationTest() {
+	}
+
+	@BeforeClass
+	public static void beforeTests() {
+		Configuration configuration = new Configuration().addAnnotatedClass(Cart.class).addAnnotatedClass(Items.class)
+				.setProperty("hibernate.dialect", H2Dialect.class.getName())
+				.setProperty("hibernate.connection.driver_class", org.h2.Driver.class.getName())
+				.setProperty("hibernate.connection.url", "jdbc:h2:mem:test")
+				.setProperty("hibernate.connection.username", "sa").setProperty("hibernate.connection.password", "")
+				.setProperty("hibernate.hbm2ddl.auto", "update");
+		ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
+				.applySettings(configuration.getProperties()).build();
+		sessionFactory = configuration.buildSessionFactory(serviceRegistry);
+	}
+
+	@Before
+	public void setUp() {
+		session = sessionFactory.openSession();
+		session.beginTransaction();
+	}
+
+	@Test
+	public void givenSession_checkIfDatabaseIsEmpty() {
+		Cart cart = (Cart) session.get(Cart.class, new Long(1));
+		assertNull(cart);
+
+	}
+
+	@Test
+	public void givenSession_checkIfDatabaseIsPopulated_afterCommit() {
+		Cart cart = new Cart();
+		Set<Items> cartItems = new HashSet<>();
+		cartItems = cart.getItems();
+		Assert.assertNull(cartItems);
+		Items item1 = new Items();
+		item1.setCart(cart);
+		assertNotNull(item1);
+		Set<Items> itemsSet = new HashSet<Items>();
+		itemsSet.add(item1);
+		assertNotNull(itemsSet);
+		cart.setItems(itemsSet);
+		assertNotNull(cart);
+		session.persist(cart);
+		session.getTransaction().commit();
+		session.close();
+
+		session = sessionFactory.openSession();
+		session.beginTransaction();
+		cart = (Cart) session.get(Cart.class, new Long(1));
+		assertNotNull(cart);
+	}
+
+	@After
+	public void tearDown() {
+		session.getTransaction().commit();
+		session.close();
+	}
+
+	@AfterClass
+	public static void afterTests() {
+		sessionFactory.close();
+	}
+
+}

persistence-modules/hibernate5-annotations/src/test/java/com/baeldung/hibernate/wherejointable/HibernateWhereJoinTableIntegrationTest.java

@@ -0,0 +1,118 @@
+package com.baeldung.hibernate.wherejointable;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.util.List;
+
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.cfg.Configuration;
+import org.hibernate.dialect.H2Dialect;
+import org.hibernate.service.ServiceRegistry;
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class HibernateWhereJoinTableIntegrationTest {
+
+    private static SessionFactory sessionFactory;
+
+    private Session session;
+
+    /**
+     * Test data
+     */
+    private User user1;
+    private User user2;
+    private User user3;
+    private Group group1;
+    private Group group2;
+
+    @BeforeClass
+    public static void beforeTests() {
+        Configuration configuration = new Configuration().addAnnotatedClass(User.class)
+            .addAnnotatedClass(Group.class)
+            .addAnnotatedClass(UserGroupRelation.class)
+            .setProperty("hibernate.dialect", H2Dialect.class.getName())
+            .setProperty("hibernate.connection.driver_class", org.h2.Driver.class.getName())
+            .setProperty("hibernate.connection.url", "jdbc:h2:mem:test")
+            .setProperty("hibernate.connection.username", "sa")
+            .setProperty("hibernate.connection.password", "")
+            .setProperty("hibernate.hbm2ddl.auto", "update");
+        
+        ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
+            .applySettings(configuration.getProperties())
+            .build();
+        
+        sessionFactory = configuration.buildSessionFactory(serviceRegistry);
+    }
+
+    @Before
+    public void setUp() {
+        session = sessionFactory.openSession();
+        session.beginTransaction();
+
+        user1 = new User("user1");
+        user2 = new User("user2");
+        user3 = new User("user3");
+
+        group1 = new Group("group1");
+        group2 = new Group("group2");
+
+        session.save(group1);
+        session.save(group2);
+
+        session.save(user1);
+        session.save(user2);
+        session.save(user3);
+
+        saveRelation(user1, group1, UserGroupRole.MODERATOR);
+        saveRelation(user2, group1, UserGroupRole.MODERATOR);
+        saveRelation(user3, group1, UserGroupRole.MEMBER);
+
+        saveRelation(user1, group2, UserGroupRole.MEMBER);
+        saveRelation(user2, group2, UserGroupRole.MODERATOR);
+    }
+
+    @After
+    public void tearDown() {
+        session.getTransaction().commit();
+        session.close();
+    }
+
+    @AfterClass
+    public static void afterTests() {
+        sessionFactory.close();
+    }
+
+    @Test
+    public void givenUser1_getGroups_returnsAllGroups() {
+        List<Group> groups = user1.getGroups();
+        assertEquals(2, groups.size());
+
+        assertTrue(groups.contains(group1));
+        assertTrue(groups.contains(group2));
+    }
+
+    @Test
+    public void givenUser1_getModeratorGroups_returnsOnlyModeratorGroups() {
+        List<Group> groups = user1.getModeratorGroups();
+        assertEquals(1, groups.size());
+
+        assertTrue(groups.contains(group1));
+    }
+
+    private void saveRelation(User user, Group group, UserGroupRole role) {
+        UserGroupRelation relation = new UserGroupRelation(user.getId(), group.getId(), role);
+
+        session.save(relation);
+        session.flush();
+        session.refresh(user);
+        session.refresh(group);
+    }
+
+}