JUnit Test Cases for Hibernate DAO

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In this tutorial, we'll walk through how to write JUnit test cases for a Hibernate DAO (Data Access Object) using the latest version of Hibernate. We'll cover setting up a test environment, creating test cases, and running these tests to ensure our DAO methods work as expected.

Prerequisites

Before we start, ensure you have the following:

• Java Development Kit (JDK) installed
• Apache Maven installed
• An IDE (Integrated Development Environment) like IntelliJ IDEA or Eclipse

Step 1: Setting Up the Project

Create a Maven Project

1. Open your IDE and create a new Maven project.
2. Define the project coordinates (groupId, artifactId, version) in the pom.xml file.

Project Structure

Your project structure should look like this:

hibernate-junit-example ├── src │ ├── main │ │ ├── java │ │ │ └── com │ │ │ └── example │ │ │ └── hibernate │ │ │ ├── App.java │ │ │ ├── model │ │ │ │ └── Student.java │ │ │ ├── util │ │ │ │ └── HibernateUtil.java │ │ │ └── dao │ │ │ └── StudentDao.java │ │ └── resources │ │ └── hibernate.cfg.xml │ ├── test │ │ └── java │ │ └── com │ │ └── example │ │ └── hibernate │ │ └── dao │ │ └── StudentDaoTest.java └── pom.xml 

Step 2: Adding Dependencies

Add the necessary dependencies for Hibernate, H2 database, and JUnit in the pom.xml file.

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://www.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.example</groupId> <artifactId>hibernate-junit-example</artifactId> <version>1.0-SNAPSHOT</version> <dependencies> <!-- Hibernate Core --> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>6.1.6.Final</version> </dependency> <!-- H2 Database --> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <version>2.1.214</version> </dependency> <!-- JUnit for testing --> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter</artifactId> <version>5.9.1</version> <scope>test</scope> </dependency> <!-- Hibernate Validator --> <dependency> <groupId>org.hibernate.validator</groupId> <artifactId>hibernate-validator</artifactId> <version>6.2.3.Final</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.8.1</version> <configuration> <source>17</source> <target>17</target> </configuration> </plugin> </plugins> </build> </project> 

Step 3: Configuring Hibernate

Create the Hibernate configuration file (hibernate.cfg.xml) in the src/main/resources directory.

hibernate.cfg.xml

<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!-- Database connection settings --> <property name="hibernate.connection.driver_class">org.h2.Driver</property> <property name="hibernate.connection.url">jdbc:h2:mem:test;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE</property> <property name="hibernate.connection.username">sa</property> <property name="hibernate.connection.password"></property> <!-- SQL dialect --> <property name="hibernate.dialect">org.hibernate.dialect.H2Dialect</property> <!-- Echo all executed SQL to stdout --> <property name="hibernate.show_sql">true</property> <!-- Drop and re-create the database schema on startup --> <property name="hibernate.hbm2ddl.auto">create</property> <!-- Names the annotated entity class --> <mapping class="com.example.hibernate.model.Student"/> </session-factory> </hibernate-configuration> 

Step 4: Creating the Entity Class

Create an Entity class Student in the com.example.hibernate.model package.

Student.java

package com.example.hibernate.model; import jakarta.persistence.Entity; import jakarta.persistence.GeneratedValue; import jakarta.persistence.GenerationType; import jakarta.persistence.Id; @Entity public class Student { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; private String name; private String email; // Getters and Setters 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 String getEmail() { return email; } public void setEmail(String email) { this.email = email; } } 

Step 5: Creating the Hibernate Utility Class

Create a utility class HibernateUtil to manage the Hibernate SessionFactory.

HibernateUtil.java

package com.example.hibernate.util; import org.hibernate.SessionFactory; import org.hibernate.boot.registry.StandardServiceRegistryBuilder; import org.hibernate.cfg.Configuration; import org.hibernate.service.ServiceRegistry; public class HibernateUtil { private static SessionFactory sessionFactory; static { try { Configuration configuration = new Configuration(); configuration.configure("hibernate.cfg.xml"); ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder() .applySettings(configuration.getProperties()).build(); sessionFactory = configuration.buildSessionFactory(serviceRegistry); } catch (Exception e) { e.printStackTrace(); } } public static SessionFactory getSessionFactory() { return sessionFactory; } } 

Step 6: Creating the DAO Class

Create a DAO (Data Access Object) class StudentDao to perform CRUD operations.

StudentDao.java

package com.example.hibernate.dao; import com.example.hibernate.model.Student; import com.example.hibernate.util.HibernateUtil; import org.hibernate.Session; import org.hibernate.Transaction; import java.util.List; public class StudentDao { public void saveStudent(Student student) { Transaction transaction = null; try (Session session = HibernateUtil.getSessionFactory().openSession()) { transaction = session.beginTransaction(); session.save(student); transaction.commit(); } catch (Exception e) { if (transaction != null) { transaction.rollback(); } e.printStackTrace(); } } public void updateStudent(Student student) { Transaction transaction = null; try (Session session = HibernateUtil.getSessionFactory().openSession()) { transaction = session.beginTransaction(); session.update(student); transaction.commit(); } catch (Exception e) { if (transaction != null) { transaction.rollback(); } e.printStackTrace(); } } public Student getStudentById(Long id) { try (Session session = HibernateUtil.getSessionFactory().openSession()) { return session.get(Student.class, id); } catch (Exception e) { e.printStackTrace(); return null; } } public List<Student> getAllStudents() { try (Session session = HibernateUtil.getSessionFactory().openSession()) { return session.createQuery("from Student", Student.class).list(); } catch (Exception e) { e.printStackTrace(); return null; } } public void deleteStudent(Long id) { Transaction transaction = null; try (Session session = HibernateUtil.getSessionFactory().openSession()) { transaction = session.beginTransaction(); Student student = session.get(Student.class, id); if (student != null) { session.delete(student); } transaction.commit(); } catch (Exception e) { if (transaction != null) { transaction.rollback(); } e.printStackTrace(); } } } 

Step 7: Writing JUnit Test Cases

Create a test class StudentDaoTest in the src/test/java/com/example/hibernate/dao package to write JUnit test cases for the StudentDao methods.

StudentDaoTest.java

package com.example.hibernate.dao; import com.example.hibernate.model.Student; import com.example.hibernate.util.HibernateUtil; import org.hibernate.Session; import org.hibernate.Transaction; import org.junit.jupiter.api.*; import java.util.List; import static org.junit.jupiter.api.Assertions.*; @TestInstance(TestInstance.Lifecycle.PER_CLASS) public class StudentDaoTest { private StudentDao studentDao; @BeforeAll public void setUp() { studentDao = new StudentDao(); } @AfterEach public void tearDown() { // Clean up after each test Transaction transaction = null; try (Session session = HibernateUtil.getSessionFactory().openSession()) { transaction = session.beginTransaction(); session.createQuery("DELETE FROM Student").executeUpdate(); transaction.commit(); } catch (Exception e) { if (transaction != null) { transaction.rollback(); } e.printStackTrace(); } } @Test public void testSaveStudent() { Student student = new Student(); student.setName("John Doe"); student.setEmail("john.doe@example.com"); studentDao.saveStudent(student); Student retrievedStudent = studentDao.getStudentById(student.getId()); assertNotNull(retrievedStudent); assertEquals(student.getName(), retrievedStudent.getName()); } @Test public void testUpdateStudent() { Student student = new Student(); student.setName("John Doe"); student.setEmail("john.doe@example.com"); studentDao.saveStudent(student); student.setName("Jane Doe"); studentDao.updateStudent(student); Student retrievedStudent = studentDao.getStudentById(student.getId()); assertNotNull(retrievedStudent); assertEquals("Jane Doe", retrievedStudent.getName()); } @Test public void testGetStudentById() { Student student = new Student(); student.setName("John Doe"); student.setEmail("john.doe@example.com"); studentDao.saveStudent(student); Student retrievedStudent = studentDao.getStudentById(student.getId()); assertNotNull(retrievedStudent); assertEquals(student.getName(), retrievedStudent.getName()); } @Test public void testGetAllStudents() { Student student1 = new Student(); student1.setName("John Doe"); student1.setEmail("john.doe@example.com"); Student student2 = new Student(); student2.setName("Jane Doe"); student2.setEmail("jane.doe@example.com"); studentDao.saveStudent(student1); studentDao.saveStudent(student2); List<Student> students = studentDao.getAllStudents(); assertNotNull(students); assertEquals(2, students.size()); } @Test public void testDeleteStudent() { Student student = new Student(); student.setName("John Doe"); student.setEmail("john.doe@example.com"); studentDao.saveStudent(student); studentDao.deleteStudent(student.getId()); Student retrievedStudent = studentDao.getStudentById(student.getId()); assertNull(retrievedStudent); } } 

Step 8: Running the Tests

To run the tests, execute the test class StudentDaoTest in your IDE or using Maven. The tests will perform the following operations:

1. Save a new student and verify that it was saved correctly.
2. Update an existing student and verify that the changes were persisted.
3. Retrieve a student by ID and verify that the correct student is returned.
4. Retrieve all students and verify that the correct number of students is returned.
5. Delete a student and verify that it was deleted correctly.

Conclusion

In this tutorial, we have walked through setting up a Hibernate project using Maven, creating an entity and DAO, and writing JUnit test cases to test the DAO methods. By following this tutorial, you should now have a good understanding of how to write JUnit test cases for Hibernate DAOs and ensure that your database operations are working correctly.