[FIXED] Optimistic locking Test in spring data JPA

Issue

I'm trying to test the optimistic locking mechanism in spring data jpa by loading a certain entity twice using findBy function, then updating the first one and asserting that when the second one is updated, it will throw an OptimisticLockingFailureException.

But the problem is that no exception is thrown and the second update is done successfully. After investigation i found that findBy function hits the database only the first time and caches the returned entity. and when i call it again it returns cached entity. which means that both loaded entities are equal. so the first update reflects in both entities making the second entity does not have the stale data.

so, how do i force loading the second entity from the data base in the second findBy function call ?

Here is my code:-

Test class

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertThrows;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureTestDatabase;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.dao.OptimisticLockingFailureException;
import org.springframework.test.context.DynamicPropertyRegistry;
import org.springframework.test.context.DynamicPropertySource;

@DataJpaTest
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
class PersistenceTests {

    @Autowired
    private ProductRepository repository;

    private ProductEntity savedEntity;

    @DynamicPropertySource
    static void databaseProperties(DynamicPropertyRegistry registry) {
        registry.add("spring.datasource.url", () -> "jdbc:mysql://localhost:3306/code_snippet");
        registry.add("spring.datasource.username", () -> "root");
        registry.add("spring.datasource.password", () -> "System");
        registry.add("spring.jpa.hibernate.ddl-auto", () -> "create-drop");

    }

    @BeforeEach
    void setupDb() {
        repository.deleteAll();

        ProductEntity entity = new ProductEntity(1, "n", 1);
        savedEntity = repository.save(entity);

        assertEqualsProduct(entity, savedEntity);
    }

    @Test
    void optimisticLockError() {

        // Store the saved entity in two separate entity objects
        ProductEntity entity1 = repository.findById(savedEntity.getId()).get();
        ProductEntity entity2 = repository.findById(savedEntity.getId()).get();

        // Update the entity using the first entity object
        entity1.setName("n1");
        repository.save(entity1);

        // Update the entity using the second entity object.
        // This should fail since the second entity now holds an old version number,
        // i.e. an Optimistic Lock Error
        assertThrows(OptimisticLockingFailureException.class, () -> {
            entity2.setName("n2");
            repository.save(entity2);
        });

        // Get the updated entity from the database and verify its new sate
        ProductEntity updatedEntity = repository.findById(savedEntity.getId()).get();
        assertEquals(1, (int) updatedEntity.getVersion());
        assertEquals("n1", updatedEntity.getName());
    }

    private void assertEqualsProduct(ProductEntity expectedEntity, ProductEntity actualEntity) {
        assertEquals(expectedEntity.getId(), actualEntity.getId());
        assertEquals(expectedEntity.getVersion(), actualEntity.getVersion());
        assertEquals(expectedEntity.getProductId(), actualEntity.getProductId());
        assertEquals(expectedEntity.getName(), actualEntity.getName());
        assertEquals(expectedEntity.getWeight(), actualEntity.getWeight());
    }
}

Entity

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Version;

@Entity
@Table(name = "product")
public class ProductEntity {

    @Id
    @GeneratedValue
    private Integer id;

    @Version
    private Integer version;

    private int productId;

    private String name;
    private int weight;

    public ProductEntity() {
    }

    public ProductEntity(int productId, String name, int weight) {
        this.productId = productId;
        this.name = name;
        this.weight = weight;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getVersion() {
        return version;
    }

    public void setVersion(Integer version) {
        this.version = version;
    }

    public int getProductId() {
        return productId;
    }

    public void setProductId(int productId) {
        this.productId = productId;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getWeight() {
        return weight;
    }

    public void setWeight(int weight) {
        this.weight = weight;
    }
}

Repository

import java.util.Optional;
import org.springframework.data.repository.PagingAndSortingRepository;

public interface ProductRepository extends PagingAndSortingRepository<ProductEntity, Integer> {

    Optional<ProductEntity> findByProductId(int productId);

}

pom.xml

<?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>2.7.2</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.javaworld.codesnippet</groupId>
    <artifactId>writing-persistence-tests</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>writing-persistence-tests</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>11</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </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>
            </plugin>
        </plugins>
    </build>

</project>

Main Class

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class WritingPersistenceTestsApplication {

    public static void main(String[] args) {
        SpringApplication.run(WritingPersistenceTestsApplication.class, args);
    }

}

Solution

The problem is that your test method is by default transactional. You can disable the transactional for this method by adding:

@Test
@Transactional(value = Transactional.TxType.NEVER)

Than you get in the second save ObjectOptimisticLockingFailureException

Answered By - pL4Gu33
Answer Checked By - Senaida (JavaFixing Volunteer)