SpringBoot系列（六）如何使用 MockMvc 或者 RestTemplate 发请求进行单元测试

本文主要功能：

对最简单的/hello接口，如何编写单元测试用例。

1、首先，要引入以下依赖

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

2、下面，我们来编写测试类

方式一、restTemplet远程调用

如果你的服务部署在远端Linux服务器上，通过本地单元测试用例，调接口，你可以通过以下方式：
首先，你在Linux服务器启动你的服务，可以看到服务端口为8888

然后，撰写代码

/**
 * @program: helloword
 * @description: <description>
 * @author: cavan
 * @create: 2021-11-30 21:36
 */
@SpringBootTest
@RunWith(SpringJUnit4ClassRunner.class)
public class RestemplateTest {

    private final static String url = "http://121.43.225.17:8888/hello";

    private static RestTemplate restTemplate = new RestTemplate();

    /**
     * 前置步骤
     */
    @Before
    public void setUp() {
    }

    @Test
    public void test() {
        ResponseEntity<String> response = restTemplate.exchange(url,
                HttpMethod.GET,
                new HttpEntity(null),
                String.class);
        Assert.assertEquals("hello world", response.getBody());
        Assert.assertEquals(response.getStatusCodeValue(), 200);
    }

    /**
     * 后置步骤
     */
    @After
    public void tearDown() {
    }
}

结果Pass，

方式二、使用mock方式单元测试

Spring测试框架提供MockMvc对象，可以在不需要客户端-服务端请求的情况下进行MVC测试，完全在服务端这边就可以执行Controller的请求，跟启动了测试服务器一样。
测试开始之前需要建立测试环境，setup方法被@Before修饰。通过MockMvcBuilders工具，使用WebApplicationContext对象作为参数，创建一个MockMvc对象。最后获取到MockServletContext这个上下文就可以进行测试了
代码如下：

@SpringBootTest
@RunWith(SpringJUnit4ClassRunner.class)
public class HellowordApplicationTests {
    private MockMvc mockMvc;

    @Autowired
    private WebApplicationContext context;

    /**
     * 前置步骤
     */
    @Before
    public void setUp() {
        mockMvc = MockMvcBuilders.webAppContextSetup(context).build();
        //        mockMvc = MockMvcBuilders.standaloneSetup((new HelloWord())).build();
    }

    @Test
    public void contextLoads() throws Exception {
        /**
         * 1、mockMvc.perform执行一个请求。
         * 2、MockMvcRequestBuilders.get("XXX")构造一个请求。
         * 3、ResultActions.param添加请求传值
         * 4、ResultActions.accept(MediaType.TEXT_HTML_VALUE))设置返回类型
         * 5、ResultActions.andExpect添加执行完成后的断言。
         * 6、ResultActions.andDo添加一个结果处理器，表示要对结果做点什么事情
         *   比如此处使用MockMvcResultHandlers.print()输出整个响应结果信息。
         * 5、ResultActions.andReturn表示执行完成后返回相应的结果。
         */
        MvcResult mvcResult =
                mockMvc.perform(MockMvcRequestBuilders.get("/hello").accept(MediaType.APPLICATION_JSON))
                        .andExpect(MockMvcResultMatchers.status().isOk())
                        .andDo(MockMvcResultHandlers.print())
                        .andReturn();
        Assert.assertEquals(200, mvcResult.getResponse().getStatus());
        Assert.assertEquals("hello world", mvcResult.getResponse().getContentAsString());
    }

    /**
     * 后置步骤
     */
    @After
    public void tearDown() {}
}

结果，pass

过程中出现的问题记录：

启动测试类的时候出现如下报错，

错误代码如下

org.junit.runners.model.InvalidTestClassError: Invalid test class 'com.cavan.helloword.MockTests':
  1. No runnable methods

	at org.junit.runners.ParentRunner.validate(ParentRunner.java:525)
	at org.junit.runners.ParentRunner.<init>(ParentRunner.java:92)
	at org.junit.runners.BlockJUnit4ClassRunner.<init>(BlockJUnit4ClassRunner.java:74)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.<init>(SpringJUnit4ClassRunner.java:137)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at org.junit.internal.builders.AnnotatedBuilder.buildRunner(AnnotatedBuilder.java:104)
	at org.junit.vintage.engine.discovery.DefensiveAllDefaultPossibilitiesBuilder$DefensiveAnnotatedBuilder.buildRunner(DefensiveAllDefaultPossibilitiesBuilder.java:114)
	at org.junit.internal.builders.AnnotatedBuilder.runnerForClass(AnnotatedBuilder.java:86)
	at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:70)
	at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:37)
	at org.junit.vintage.engine.discovery.DefensiveAllDefaultPossibilitiesBuilder.runnerForClass(DefensiveAllDefaultPossibilitiesBuilder.java:57)
	at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:70)
	at org.junit.vintage.engine.discovery.ClassSelectorResolver.resolveTestClass(ClassSelectorResolver.java:66)
	at org.junit.vintage.engine.discovery.ClassSelectorResolver.resolve(ClassSelectorResolver.java:47)
	at org.junit.platform.engine.support.discovery.EngineDiscoveryRequestResolution.lambda$resolve$2(EngineDiscoveryRequestResolution.java:134)
	at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
	at java.util.ArrayList$ArrayListSpliterator.tryAdvance(ArrayList.java:1359)
	at java.util.stream.ReferencePipeline.forEachWithCancel(ReferencePipeline.java:126)
	at java.util.stream.AbstractPipeline.copyIntoWithCancel(AbstractPipeline.java:498)
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:485)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
	at java.util.stream.FindOps$FindOp.evaluateSequential(FindOps.java:152)
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.util.stream.ReferencePipeline.findFirst(ReferencePipeline.java:464)
	at org.junit.platform.engine.support.discovery.EngineDiscoveryRequestResolution.resolve(EngineDiscoveryRequestResolution.java:185)
	at org.junit.platform.engine.support.discovery.EngineDiscoveryRequestResolution.resolve(EngineDiscoveryRequestResolution.java:125)
	at org.junit.platform.engine.support.discovery.EngineDiscoveryRequestResolution.access$100(EngineDiscoveryRequestResolution.java:57)
	at org.junit.platform.engine.support.discovery.EngineDiscoveryRequestResolution$DefaultContext.resolve(EngineDiscoveryRequestResolution.java:224)
	at org.junit.vintage.engine.discovery.MethodSelectorResolver.resolveParentAndAddFilter(MethodSelectorResolver.java:56)
	at org.junit.vintage.engine.discovery.MethodSelectorResolver.resolve(MethodSelectorResolver.java:40)
	at org.junit.platform.engine.support.discovery.EngineDiscoveryRequestResolution.lambda$resolve$2(EngineDiscoveryRequestResolution.java:146)
	at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
	at java.util.ArrayList$ArrayListSpliterator.tryAdvance(ArrayList.java:1359)
	at java.util.stream.ReferencePipeline.forEachWithCancel(ReferencePipeline.java:126)
	at java.util.stream.AbstractPipeline.copyIntoWithCancel(AbstractPipeline.java:498)
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:485)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
	at java.util.stream.FindOps$FindOp.evaluateSequential(FindOps.java:152)
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.util.stream.ReferencePipeline.findFirst(ReferencePipeline.java:464)
	at org.junit.platform.engine.support.discovery.EngineDiscoveryRequestResolution.resolve(EngineDiscoveryRequestResolution.java:185)
	at org.junit.platform.engine.support.discovery.EngineDiscoveryRequestResolution.resolve(EngineDiscoveryRequestResolution.java:125)
	at org.junit.platform.engine.support.discovery.EngineDiscoveryRequestResolution.resolveCompletely(EngineDiscoveryRequestResolution.java:91)
	at org.junit.platform.engine.support.discovery.EngineDiscoveryRequestResolution.run(EngineDiscoveryRequestResolution.java:82)
	at org.junit.platform.engine.support.discovery.EngineDiscoveryRequestResolver.resolve(EngineDiscoveryRequestResolver.java:113)
	at org.junit.vintage.engine.discovery.VintageDiscoverer.discover(VintageDiscoverer.java:44)
	at org.junit.vintage.engine.VintageTestEngine.discover(VintageTestEngine.java:63)
	at org.junit.platform.launcher.core.DefaultLauncher.discoverEngineRoot(DefaultLauncher.java:181)
	at org.junit.platform.launcher.core.DefaultLauncher.discoverRoot(DefaultLauncher.java:168)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:132)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:221)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)

经过定位发现，导入的Test包错误，这是我导入的包路径：import org.junit.jupiter.api.Test;
正确的路径：import org.junit.Test;

注意：重点注意下，@RunWith()这个注释一定要有，因为调用controller方法需要重启一个controller，要运行，就需要一个端口，这个可以随机开启一个端口供测试用。

本文Gitee代码链接：https://gitee.com/cavan2021/springboot/tree/master/helloword
参考：https://blog.csdn.net/qq_44014971/article/details/108056557