概述

@SpringBootTest注解是SpringBoot自1.4.0版本开始引入的一个用于测试的注解。基本用法如下：

1. 添加Maven依赖

<properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.6.RELEASE</version>
    </parent>

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

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

2. 编写启动入口类

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

3. 编写Controller类

@RestController
public class HelloController {

    @RequestMapping("/")
    public String index() {
        return "Hello Spring Boot,Index!";
    }

    @RequestMapping(value = "/test", method = RequestMethod.GET)
    public String test() {
        return "Spring Boot Test Demo!";
    }
}

4. 编写测试类

@RunWith(SpringRunner.class)
@SpringBootTest(classes = StartUpApplication.class, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class HelloControllerTest {

    /**
     * @LocalServerPort 提供了 @Value("${local.server.port}") 的代替
     */
    @LocalServerPort
    private int port;

    private URL base;

    @Autowired
    private TestRestTemplate restTemplate;

    @Before
    public void setUp() throws Exception {
        String url = String.format("http://localhost:%d/", port);
        System.out.println(String.format("port is : [%d]", port));
        this.base = new URL(url);
    }

    /**
     * 向"/test"地址发送请求，并打印返回结果
     * @throws Exception
     */
    @Test
    public void test1() throws Exception {

        ResponseEntity<String> response = this.restTemplate.getForEntity(
                this.base.toString() + "/test", String.class, "");
        System.out.println(String.format("测试结果为：%s", response.getBody()));
    }

其中，classes属性指定启动类，SpringBootTest.WebEnvironment.RANDOM_PORT经常和测试类中@LocalServerPort一起在注入属性时使用。会随机生成一个端口号。

总结

我们发现，随着Spring boot 版本的提升，单元测试变得更简单了。