Using Spring MVC Test to unit test multipart POST request

spring, spring-mvc, unit-testing

Solution

Since `MockMvcRequestBuilders#fileUpload` is deprecated, you'll want to use `MockMvcRequestBuilders#multipart(String, Object...)` which returns a `MockMultipartHttpServletRequestBuilder`. Then chain a bunch of `file(MockMultipartFile)` calls.

Here's a working example. Given a `@Controller`

@Controller
public class NewController {

    @RequestMapping(value = "/upload", method = RequestMethod.POST)
    @ResponseBody
    public String saveAuto(
            @RequestPart(value = "json") JsonPojo pojo,
            @RequestParam(value = "some-random") String random,
            @RequestParam(value = "data", required = false) List<MultipartFile> files) {
        System.out.println(random);
        System.out.println(pojo.getJson());
        for (MultipartFile file : files) {
            System.out.println(file.getOriginalFilename());
        }
        return "success";
    }

    static class JsonPojo {
        private String json;

        public String getJson() {
            return json;
        }

        public void setJson(String json) {
            this.json = json;
        }

    }
}

and a unit test

@WebAppConfiguration
@ContextConfiguration(classes = WebConfig.class)
@RunWith(SpringJUnit4ClassRunner.class)
public class Example {

    @Autowired
    private WebApplicationContext webApplicationContext;

    @Test
    public void test() throws Exception {

        MockMultipartFile firstFile = new MockMultipartFile("data", "filename.txt", "text/plain", "some xml".getBytes());
        MockMultipartFile secondFile = new MockMultipartFile("data", "other-file-name.data", "text/plain", "some other type".getBytes());
        MockMultipartFile jsonFile = new MockMultipartFile("json", "", "application/json", "{\"json\": \"someValue\"}".getBytes());

        MockMvc mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext).build();
        mockMvc.perform(MockMvcRequestBuilders.multipart("/upload")
                        .file(firstFile)
                        .file(secondFile)
                        .file(jsonFile)
                        .param("some-random", "4"))
                    .andExpect(status().is(200))
                    .andExpect(content().string("success"));
    }
}

And the `@Configuration` class

@Configuration
@ComponentScan({ "test.controllers" })
@EnableWebMvc
public class WebConfig extends WebMvcConfigurationSupport {
    @Bean
    public MultipartResolver multipartResolver() {
        CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();
        return multipartResolver;
    }
}

The test should pass and give you output of

4 // from param
someValue // from json file
filename.txt // from first file
other-file-name.data // from second file

The thing to note is that you are sending the JSON just like any other multipart file, except with a different content type.

Problem

I have the following request handler for saving autos. I have verified that this works when I use e.g. cURL. Now I want to unit test the method with Spring MVC Test. I have tried to use the fileUploader, but I am not managing to get it working. Nor do I manage to add the JSON part. How would I unit test this method with Spring MVC Test? I am not able to find any examples on this. ``` @RequestMapping(value = "autos", method = RequestMethod.POST) public ResponseEntity saveAuto( @RequestPart(value = "data") autoResource, @RequestParam(value = "files[]", required = false) List<MultipartFile> files) { // ... } ``` I want to uplod a JSON representation for my auto + one or more files. I will add 100 in bounty to the correct answer!

Original source