如何在SpringBoot中整合H2进行单元测试？

主要步骤分为添加Maven依赖，创建SQL脚本，创建实体类、创建Mapper，创建application-testing.yml（用于配置H2和扫描Mapper），创建单元测试。

1. 添加Maven依赖，如下

 <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
 <dependencies>
        <!-- h2，用于单元测试 -->
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <version>1.4.197</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatisplus-spring-boot-starter</artifactId>
            <version>1.0.5</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus</artifactId>
            <version>2.2.0</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.38</version>
        </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>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

2. 在resources目录下创建SQL脚本，用于创建H2的数据库、填充测试数据
   注意，H2的表创建要注意关键字大写，否则执行单元测试时提示表不存在。

# db/schema-h2.sql
DROP TABLE IF EXISTS user;

CREATE TABLE user
(
    id BIGINT(20) NOT NULL COMMENT '主键ID',
    name VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',
    age INT(11) NULL DEFAULT NULL COMMENT '年龄',
    email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱',
    PRIMARY KEY (id)
);

# db/data-h2.sql
DELETE FROM user;

INSERT INTO user (id, name, age, email) VALUES
(1, 'Jone', 18, 'test1@baomidou.com'),
(2, 'Jack', 20, 'test2@baomidou.com'),
(3, 'Tom', 28, 'test3@baomidou.com'),
(4, 'Sandy', 21, 'test4@baomidou.com'),
(5, 'Billie', 24, 'test5@baomidou.com');

3. 创建实体类
   不需要声明@TableName

@Data
public class User {
    private Long id;
    private String name;
    private Integer age;
    private String email;
}

4. 创建Mapper

@Mapper
public interface UserMapper extends BaseMapper<User> {
}

5. 创建配置application-testing.yml
   单独创建一个配置文件，是为了专门用于单元测试，与dev、test、prod等环境区分开。配置H2、扫描Mapper。

spring:
  datasource: 
    driver-class-name: org.h2.Driver
    schema: classpath:db/schema-h2.sql
    data: classpath:db/data-h2.sql
    url: jdbc:h2:mem:testdb
    username: sa
    password: sa
    continue-on-error: true

mybatis-plus:
  mapper-locations: classpath:mapper/**/*.xml
  #实体扫描，多个package用逗号或者分号分隔
  typeAliasesPackage: com.jerry.entity

6. 创建单元测试

@RunWith(SpringRunner.class)
@SpringBootTest
@ActiveProfiles("testing") //指定激活的profile
public class UserMapperTest {
    @Autowired
    private UserMapper userMapper;

    @Test
    public void testSelect(){
        System.out.println("----selectAll method test----");
        //传null表示没有限制条件
        List<User> userList = userMapper.selectList(null);
        Assert.assertEquals(5, userList.size());
        userList.forEach(System.out::println);
    }
}

运行单元测试即可。