使用 Junit 和 Mockito 测试 Spring Boot 多部分 POST 请求答案

【问题标题】：Testing a Spring Boot Multipart POST Request using Junit and Mockito使用 Junit 和 Mockito 测试 Spring Boot 多部分 POST 请求
【发布时间】：2021-09-07 08:17:03
【问题描述】：

我对测试驱动的 Web 应用程序开发相当陌生。我构建了一个示例照片上传应用程序来了解基础知识。 POST 和 GET 请求 API 可以很容易地用 postman 测试而不会出现任何错误。在 POST 请求中，我发送一个图像文件和该图像的标题。它的内容类型是 Multipart/form-data。我想使用 MockMVC 为相同的 POST 方法编写测试。我遵循了关于测试多部分发布请求1 的简短教程。但是，我得到一个空指针异常，我不确定这是否是测试发布请求 API 的正确方法。我不能同时发布文件和标题：'test-title' 作为参数吗？我想知道测试这种 API 的最佳实践。我会很高兴的。如果有人可以提供帮助。

服务类：

@Service
public class PhotoService {


    @Autowired
    private PhotoRepository photoRepo;


    public Photo addPhoto(String title, MultipartFile file) throws IOException{
        Photo photo = new Photo(title);
        photo.setImage(new Binary(BsonBinarySubType.BINARY, file.getBytes()));
        return photoRepo.insert(photo);
    }

    public Photo getPhoto(String id ){
        return photoRepo.findById(id).get();
    }

}

控制器类：

@RestController
public class PhotoController {
    @Autowired
    private PhotoService photoService;

    @Autowired
    private PhotoRepository photoRepo;


    @PostMapping("/photos/add")
    public String addPhoto(@RequestParam("title") String title, @RequestParam("image") MultipartFile image)
        throws IOException{
            System.out.print(title);
            String id = photoService.addPhoto(title, image).getId();
            return "redirect:/photos/" + id;
    }

    @GetMapping("/photos/{id}")
    public String getPhoto(@PathVariable String id, Model model)
        throws IOException{
            Photo photo = photoService.getPhoto(id);
            model.addAttribute("title", photo.getTitle());
            model.addAttribute("image", Base64.getEncoder().encodeToString(photo.getImage().getData()));
            return "photos";
    }
}

控制器测试类：

@ExtendWith(SpringExtension.class)
@WebMvcTest(controllers = PhotoController.class)
class PhotoControllerTest {


    @Autowired
    private MockMvc mockMvc;
    @MockBean
    private PhotoService photoService;
    @MockBean
    private PhotoRepository photoRepository;

    @Test
    public void whenPhotoAdded_thenVerifyStatus()
            throws Exception {
        MockMultipartFile file
                = new MockMultipartFile(
                "image",
                "/Users/x/y/z/t.jpeg",
                MediaType.IMAGE_JPEG_VALUE,
                "image".getBytes()
        );

        mockMvc.perform(multipart("/photos/add").file(file).param("title", "test-title")).andExpect(status().isOk());
    }

异常堆栈跟踪：

java.lang.NullPointerException
    at com.example.optiimsample.controller.PhotoController.addPhoto(PhotoController.java:37)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1064)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:681)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
    at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:72)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:764)
    at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:167)
    at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
    at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:183)
    at com.example.optiimsample.controller.PhotoControllerTest.whenPhotoAdded_thenVerifyStatus(PhotoControllerTest.java:57)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:688)
    at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
    at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
    at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
    at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
    at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:210)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:206)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:131)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:65)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
    at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
    at java.util.ArrayList.forEach(ArrayList.java:1257)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:143)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
    at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
    at java.util.ArrayList.forEach(ArrayList.java:1257)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:143)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
    at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:108)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:96)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:75)
    at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
    at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
    at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
    at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)

ps：这是一个实验性应用程序开发，我很乐意专注于如何测试而不是它的用法和功能。

谢谢。

【问题讨论】：

你从哪里得到 Nullpointer？你能分享一下stacktrace吗？
我还添加了异常堆栈跟踪和服务类。我想问题出在 addPhoto 方法中。
看起来像“photoService.addPhoto(title, image)”返回空值。因为你没有预料到并返回了一些东西。

标签： java spring-boot spring-mvc testing mockmvc

【解决方案1】：

看起来photoService.addPhoto(title, image) 返回null。因为你没想到会返回一些东西。

由于调用了photoService 方法并且photoService 是模拟的，因此您需要将模拟值传递给它，如下所示：

when(photoService.addPhoto(anyString(), anyObject()).thenReturn(${yourObject});

这应该在 API 调用之前。

【讨论】：

我添加了以下几行：Binary binary_test_img = new Binary(BsonBinarySubType.BINARY, "testing binary".getBytes());Photo photo = new Photo("idTest", "title", binary_test_img);when(photoService.addPhoto("title",file)).thenReturn(photo);mockMvc.perform(multipart("/photos/add").file(file).param("title", "test-title")).andExpect(status().isOk());。
那么你的结果是什么？
它不起作用，仍然报错。是否有替代方法，例如不模拟服务？这合适吗？ org.springframework.web.util.NestedServletException：请求处理失败；嵌套异常是 org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014) 处的 java.lang.NullPointerException
现在看起来像一些不同的错误。如果你删除了 @MockBean 部分，它应该可以作为集成测试。