Spring Data JPA Repository Testing using Spring Boot @DataJpaTest

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In this article, we will learn how to test Spring Data JPA Repositories using Spring Boot provided @DataJpaTest annotation.
Sometimes we might want to test the persistence layer components of our application, which doesn’t require the loading of many components like controllers, security configuration, and so on. 

So Spring Boot provides the @DataJpaTest annotation to test the only repository/persistence layer components of our Spring boot application ( The @DataJpaTest annotation doesn’t load other Spring beans (@Components, @Controller, @Service, and annotated beans) into ApplicationContext).

We use Spring boot starter test dependency to write JUnit tests for Repository layer components:
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>

Overview of Spring Boot Starter Test Dependency

The Spring Boot Starter Test dependency is a primary dependency for testing the Spring Boot Applications. It holds all the necessary elements required for the testing.

This starter includes:
  1. Spring-specific dependencies 
  2. Dependencies for auto-configuration 
  3. Set of testing libraries - JUnit, Mockito, Hamcrest, AssertJ, JSONassert, and JsonPath.
Spring Boot Starter Test dependency adds all the required dependencies to Unit test  Repository layer components so we don't have to add testing libraries.

@DataJpaTest Annotation Overview

Spring Boot provides the @DataJpaTest annotation to test the persistence layer components that will autoconfigure in-memory embedded databases and scan for @Entity classes and Spring Data JPA repositories. 

The @DataJpaTest annotation doesn’t load other Spring beans (@Components, @Controller, @Service, and annotated beans) into ApplicationContext.

To test Spring Data JPA repositories or any other JPA-related components for that matter, Spring Boot provides the @DataJpaTest annotation. We can just add it to our unit test and it will set up a Spring application context: 
@ExtendWith(SpringExtension.class)
@DataJpaTest
class UserEntityRepositoryTest {

     @Autowired private DataSource dataSource;
     @Autowired private JdbcTemplate jdbcTemplate;
     @Autowired private EntityManager entityManager;
     @Autowired private UserRepository userRepository;

     @Test
     void injectedComponentsAreNotNull(){
          assertThat(dataSource).isNotNull();
          assertThat(jdbcTemplate).isNotNull();
          assertThat(entityManager).isNotNull();
          assertThat(userRepository).isNotNull();
     }
}
In this article, we will focus on Unit testing Spring Data JPA repositories. 
Let's create a Spring boot project from scratch to demonstrate Unit testing Spring Data JPA repositories.

1. Tools and Technologies Used

  • Spring Boot - 3+
  • JDK - 17 or later
  • Spring Framework - 6
  • H2
  • Maven - 3+
  • IDE - IntelliJ IDEA

2. Creating and Importing a Project

Spring Boot provides a web tool called https://start.spring.io to bootstrap an application quickly. Just go to https://start.spring.io and generate a new spring boot project.

Use the below details in the Spring boot creation:

Project Name: spring-boot-testing

Project Type: Maven

Choose dependencies:  Spring Data JPA, H2 database, Lombok

Package name: net.javaguides.springboot

3. Maven Dependencies

Here is the complete pom.xml for your reference:

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>3.0.4</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>net.javaguides</groupId>
	<artifactId>spring-boot-testing</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>spring-boot-testing</name>
	<description>Spring boot unit testing and integration testing</description>
	<properties>
		<java.version>17</java.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>

		<dependency>
			<groupId>com.h2database</groupId>
			<artifactId>h2</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
				<configuration>
					<excludes>
						<exclude>
							<groupId>org.projectlombok</groupId>
							<artifactId>lombok</artifactId>
						</exclude>
					</excludes>
				</configuration>
			</plugin>
		</plugins>
	</build>

</project>

4. Create JPA Entity - Employee.java

Let's create a model package inside a base package "net.javaguides.springboot". 

Within the model package, create an Employee class with the following content:
package net.javaguides.springboot.model;

import lombok.*;

import jakarta.persistence.*;

@Setter
@Getter
@AllArgsConstructor
@NoArgsConstructor
@Builder

@Entity
@Table(name = "employees")
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @Column(name = "first_name", nullable = false)
    private String firstName;

    @Column(name = "last_name", nullable = false)
    private String lastName;

    @Column(nullable = false)
    private String email;
}
Note that we are using Lombok annotations to reduce the boilerplate code.

5. Create Spring Data JPA Repository

The next thing we’re gonna do is to create a repository to access an Employee's data from the database.

The JpaRepository interface defines methods for all the CRUD operations on the entity, and a default implementation of the JpaRepository called SimpleJpaRepository.

Let's create a repository package inside a base package "net.javaguides.springdatarest".

Within the repository package, create an EmployeeRepository interface with the following content:
package net.javaguides.springboot.repository;

import net.javaguides.springboot.model.Employee;
import org.springframework.data.jpa.repository.JpaRepository;

import java.util.Optional;

public interface EmployeeRepository extends JpaRepository<Employee, Long> {

}

6. JUnit Tests for Spring Data JPA Repository

Spring Boot provides the @DataJpaTest annotation to test the persistence layer components that will autoconfigure in-memory embedded databases and scan for @Entity classes and Spring Data JPA repositories. 

The @DataJpaTest annotation doesn’t load other Spring beans (@Components, @Controller, @Service, and annotated beans) into ApplicationContext.

Head over to the test package. Let's create a repository package inside a base package "test.net.javaguides.springboot". 

Within the repository package, create an EmployeeRepositoryTests class with the following content:
package net.javaguides.springboot.repository;

import net.javaguides.springboot.model.Employee;
import static org.assertj.core.api.Assertions.assertThat;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;

import java.util.List;
import java.util.Optional;

@DataJpaTest
public class EmployeeRepositoryTests {

    @Autowired
    private EmployeeRepository employeeRepository;

    private Employee employee;

    @BeforeEach
    public void setup(){
        employee = Employee.builder()
                .firstName("Ramesh")
                .lastName("Fadatare")
                .email("ramesh@gmail,com")
                .build();
    }

    // JUnit test for save employee operation
    //@DisplayName("JUnit test for save employee operation")
    @Test
    public void givenEmployeeObject_whenSave_thenReturnSavedEmployee(){

        //given - precondition or setup
        Employee employee = Employee.builder()
                .firstName("Ramesh")
                .lastName("Ramesh")
                .email("ramesh@gmail,com")
                .build();
        // when - action or the behaviour that we are going test
        Employee savedEmployee = employeeRepository.save(employee);

        // then - verify the output
        assertThat(savedEmployee).isNotNull();
        assertThat(savedEmployee.getId()).isGreaterThan(0);
    }


    // JUnit test for get all employees operation
    @DisplayName("JUnit test for get all employees operation")
    @Test
    public void givenEmployeesList_whenFindAll_thenEmployeesList(){
        // given - precondition or setup

        Employee employee1 = Employee.builder()
                .firstName("John")
                .lastName("Cena")
                .email("cena@gmail,com")
                .build();

        employeeRepository.save(employee);
        employeeRepository.save(employee1);

        // when -  action or the behaviour that we are going test
        List<Employee> employeeList = employeeRepository.findAll();

        // then - verify the output
        assertThat(employeeList).isNotNull();
        assertThat(employeeList.size()).isEqualTo(2);

    }

    // JUnit test for get employee by id operation
    @DisplayName("JUnit test for get employee by id operation")
    @Test
    public void givenEmployeeObject_whenFindById_thenReturnEmployeeObject(){

        employeeRepository.save(employee);

        // when -  action or the behaviour that we are going test
        Employee employeeDB = employeeRepository.findById(employee.getId()).get();

        // then - verify the output
        assertThat(employeeDB).isNotNull();
    }

    // JUnit test for update employee operation
    @DisplayName("JUnit test for update employee operation")
    @Test
    public void givenEmployeeObject_whenUpdateEmployee_thenReturnUpdatedEmployee(){

        employeeRepository.save(employee);

        // when -  action or the behaviour that we are going test
        Employee savedEmployee = employeeRepository.findById(employee.getId()).get();
        savedEmployee.setEmail("ram@gmail.com");
        savedEmployee.setFirstName("Ram");
        Employee updatedEmployee =  employeeRepository.save(savedEmployee);

        // then - verify the output
        assertThat(updatedEmployee.getEmail()).isEqualTo("ram@gmail.com");
        assertThat(updatedEmployee.getFirstName()).isEqualTo("Ram");
    }

    // JUnit test for delete employee operation
    @DisplayName("JUnit test for delete employee operation")
    @Test
    public void givenEmployeeObject_whenDelete_thenRemoveEmployee(){

        employeeRepository.save(employee);

        // when -  action or the behaviour that we are going test
        employeeRepository.deleteById(employee.getId());
        Optional<Employee> employeeOptional = employeeRepository.findById(employee.getId());

        // then - verify the output
        assertThat(employeeOptional).isEmpty();
    }
}
Note that we are using the assertThat() method from the AssertJ library for assertions.

Let's understand the above JUnit tests one by one.

We have used @BeforeEach annotation to signal that the annotated method should be executed before each @Test method in the current test class:

    @BeforeEach
    public void setup(){
        employee = Employee.builder()
                .firstName("Ramesh")
                .lastName("Fadatare")
                .email("ramesh@gmail,com")
                .build();
    }
JUnit test to save employee operation:

    // JUnit test for save employee operation
    //@DisplayName("JUnit test for save employee operation")
    @Test
    public void givenEmployeeObject_whenSave_thenReturnSavedEmployee(){

        //given - precondition or setup
        Employee employee = Employee.builder()
                .firstName("Ramesh")
                .lastName("Ramesh")
                .email("ramesh@gmail,com")
                .build();
        // when - action or the behaviour that we are going test
        Employee savedEmployee = employeeRepository.save(employee);

        // then - verify the output
        assertThat(savedEmployee).isNotNull();
        assertThat(savedEmployee.getId()).isGreaterThan(0);
    }
JUnit test to get all employees operation
// JUnit test for get all employees operation
    @DisplayName("JUnit test for get all employees operation")
    @Test
    public void givenEmployeesList_whenFindAll_thenEmployeesList(){
        // given - precondition or setup

        Employee employee1 = Employee.builder()
                .firstName("John")
                .lastName("Cena")
                .email("cena@gmail,com")
                .build();

        employeeRepository.save(employee);
        employeeRepository.save(employee1);

        // when -  action or the behaviour that we are going test
        List<Employee> employeeList = employeeRepository.findAll();

        // then - verify the output
        assertThat(employeeList).isNotNull();
        assertThat(employeeList.size()).isEqualTo(2);

    }
JUnit test to get single employee by id operation

    // JUnit test for get employee by id operation
    @DisplayName("JUnit test for get employee by id operation")
    @Test
    public void givenEmployeeObject_whenFindById_thenReturnEmployeeObject(){

        employeeRepository.save(employee);

        // when -  action or the behaviour that we are going test
        Employee employeeDB = employeeRepository.findById(employee.getId()).get();

        // then - verify the output
        assertThat(employeeDB).isNotNull();
    }
JUnit test to update employee operation

// JUnit test for update employee operation
    @DisplayName("JUnit test for update employee operation")
    @Test
    public void givenEmployeeObject_whenUpdateEmployee_thenReturnUpdatedEmployee(){

        employeeRepository.save(employee);

        // when -  action or the behaviour that we are going test
        Employee savedEmployee = employeeRepository.findById(employee.getId()).get();
        savedEmployee.setEmail("ram@gmail.com");
        savedEmployee.setFirstName("Ram");
        Employee updatedEmployee =  employeeRepository.save(savedEmployee);

        // then - verify the output
        assertThat(updatedEmployee.getEmail()).isEqualTo("ram@gmail.com");
        assertThat(updatedEmployee.getFirstName()).isEqualTo("Ram");
    }
JUnit test for delete employee operation
// JUnit test for delete employee operation
    @DisplayName("JUnit test for delete employee operation")
    @Test
    public void givenEmployeeObject_whenDelete_thenRemoveEmployee(){

        employeeRepository.save(employee);

        // when -  action or the behaviour that we are going test
        employeeRepository.deleteById(employee.getId());
        Optional<Employee> employeeOptional = employeeRepository.findById(employee.getId());

        // then - verify the output
        assertThat(employeeOptional).isEmpty();
    }
}

7. Running JUnit Tests

When you run EmployeeRepositoryTests, Spring Boot will autoconfigure the H2 in-memory embedded database (as you have the H2 database driver in the classpath) and run the tests.

The output of the tests is shown below screenshot:

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Related Spring and Spring Boot Tutorials/Guides:

Spring Boot Tutorials [500+] Spring Boot Testing Tutorial Spring Boot Microservice Tutorial Spring Boot Kafka Microservices Spring Boot + Apache Kafka Tutorial Spring Core Tutorial Spring MVC Tutorial Spring Data JPA Tutorial Spring Framework for Beginners Spring AOP Tutorial Spring Security Tutorial Spring Exceptions Tutorial Spring Boot Interview Questions Spring Boot Microservices Interview Questions Apache Kafka Tutorials Docker Tutorials and Guides Spring Boot RabbitMQ Tutorials Angular CRUD Example with Spring Boot Spring Boot + Angular 12 CRUD Full Stack Spring Boot + Angular 8 CRUD Full Stack Spring Boot + Angular 10 CRUD Full Stack Spring Boot + React JS CRUD Full Stack React JS ( React Hooks) + Spring Boot Spring Boot Thymeleaf CRUD Full Stack Spring Boot User Registration and Login Node Js + Express + MongoDB CRUD Vue JS + Spring Boot REST API Tutorial

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