Spring Boot TestEntityManager 教程

Spring Boot TestEntityManager 教程展示了如何在 JPA 测试中使用 TestEntityManager。 TestEntityManager 提供了 EntityManager 方法的子集，可用于测试以及用于常见测试任务（例如 persist 或 find）的辅助方法。

Spring 是用于创建企业应用的流行 Java 应用框架。 Spring Boot 是 Spring 框架的演进，可帮助您轻松创建独立的，生产级的基于 Spring 的应用。

TestEntityManager

TestEntityManager允许在测试中使用EntityManager。 Spring Repository是EntityManager的抽象； 它使开发人员免受 JPA 底层细节的困扰，并带来了许多便捷的方法。 但是 Spring 允许在应用代码和测试中需要时使用EntityManager。

在我们的测试中，我们可以从应用中注入 DataSource，@ JdbcTemplate，@ EntityManager 或任何 Spring Data 存储库。

Spring TestEntityManager示例

以下应用使用TestEntityManager以测试方法保存了一些城市实体。

pom.xml
src
├───main
│   ├───java
│   │   └───com
│   │       └───zetcode
│   │           │   Application.java
│   │           │   MyRunner.java
│   │           ├───model
│   │           │       City.java
│   │           └───repository
│   │                   CityRepository.java
│   └───resources
└───test
    └───java
        └───com
            └───zetcode
                └───repository
                        CityRepositoryTest.java

这是项目结构。

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
         http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.zetcode</groupId>
    <artifactId>springboottestentitymanager</artifactId>
    <version>1.0-SNAPSHOT</version>

    <packaging>jar</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.1.RELEASE</version>
    </parent>

    <dependencies>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>

        </plugins>
    </build>

</project>

Maven POM 文件包含 Spring Data JPA，测试和 H2 数据库的依赖项。

com/zetcode/model/City.java

package com.zetcode.model;

import java.util.Objects;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "cities")
public class City {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private String name;
    private int population;

    public City() {
    }

    public City(String name, int population) {
        this.name = name;
        this.population = population;
    }

    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 int getPopulation() {
        return population;
    }

    public void setPopulation(int population) {
        this.population = population;
    }

    @Override
    public int hashCode() {
        int hash = 7;
        hash = 79 * hash + Objects.hashCode(this.id);
        hash = 79 * hash + Objects.hashCode(this.name);
        hash = 79 * hash + this.population;
        return hash;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final City other = (City) obj;
        if (this.population != other.population) {
            return false;
        }
        if (!Objects.equals(this.name, other.name)) {
            return false;
        }
        return Objects.equals(this.id, other.id);
    }

    @Override
    public String toString() {

        var builder = new StringBuilder();
        builder.append("City{id=").append(id).append(", name=")
                .append(name).append(", population=")
                .append(population).append("}");

        return builder.toString();
    }
}

这是City实体。

com/zetcode/repository/CityRepository.java

package com.zetcode.repository;

import com.zetcode.model.City;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public interface CityRepository extends CrudRepository<City, Long> {

    List<City> findByName(String name);
}

CityRepository包含自定义的findByName()方法。 Spring 检查方法的名称，并从其关键字派生查询。

com/zetcode/MyRunner.java

package com.zetcode;

import com.zetcode.model.City;
import com.zetcode.repository.CityRepository;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

@Component
public class MyRunner implements CommandLineRunner {

    private static final Logger logger = LoggerFactory.getLogger(MyRunner.class);

    @Autowired
    private CityRepository cityRepository;

    @Override
    public void run(String... args) throws Exception {

        logger.info("Saving cities");

        cityRepository.save(new City("Bratislava", 432000));
        cityRepository.save(new City("Budapest", 1759000));
        cityRepository.save(new City("Prague", 1280000));
        cityRepository.save(new City("Warsaw", 1748000));

        logger.info("Retrieving cities");

        var cities = cityRepository.findAll();
        cities.forEach(city -> logger.info("{}", city));
    }
}

在MyRunner中，我们使用CityRepository保存和检索实体。 数据存储在内存中的 H2 数据库中。

Note: In Java enterprise applications it is a good practice to define a service layer that works with repositories. For simplicity reasons, we skip the service layer.

com/zetcode/Application.java

package com.zetcode;

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

@SpringBootApplication
public class Application {

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

Application设置 Spring Boot 应用。 @SpringBootApplication启用自动配置和组件扫描。

com/zetcode/repository/CityRepositoryTest.java

package com.zetcode.repository;

import com.zetcode.model.City;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManager;
import org.springframework.test.context.junit4.SpringRunner;

import static org.assertj.core.api.Assertions.assertThat;
import static org.junit.Assert.assertEquals;

@RunWith(SpringRunner.class)
@DataJpaTest
public class CityRepositoryTest {

    @Autowired
    private TestEntityManager entityManager;

    @Autowired
    private CityRepository repository;

    @Test
    public void testFindByName() {

        entityManager.persist(new City("Bratislava", 432000));
        entityManager.persist(new City("Budapest", 1759000));
        entityManager.persist(new City("Prague", 1280000));
        entityManager.persist(new City("Warsaw", 1748000));

        var cities = repository.findByName("Bratislava");
        assertEquals(1, cities.size());

        assertThat(cities).extracting(City::getName).containsOnly("Bratislava");
    }
}

在CityRepositoryTest中，我们测试了自定义 JPA 方法。

@Autowired
private TestEntityManager entityManager;

我们注入TestEntityManager。

@RunWith(SpringRunner.class)
@DataJpaTest
public class CityRepositoryTest {

@DataJpaTest用于测试 JPA 信息库。 它与@RunWith（SpringRunner.class）结合使用。 注解会禁用完全自动配置，并且仅应用与 JPA 测试相关的配置。 默认情况下，用@DataJpaTest 注解的测试使用嵌入式内存数据库。

entityManager.persist(new City("Bratislava", 432000));
entityManager.persist(new City("Budapest", 1759000));
entityManager.persist(new City("Prague", 1280000));
entityManager.persist(new City("Warsaw", 1748000));

我们用EntityManager's persist()方法保存了四个城市。

var cities = repository.findByName("Bratislava");
assertEquals(1, cities.size());

我们测试findByName()方法返回一个城市。

assertThat(cities).extracting(City::getName).containsOnly("Bratislava");

在这里，我们测试城市的名称。

$ mvn spring-boot:test

我们运行测试。

在本教程中，我们在测试中使用了TestEntityManager。