Unable to pass multipart file through mockMvc

Question

I am writing junit test for my request method. Im using mockMvc to trigger the rest request. When I run my test I get the error

java.lang.NullPointerException: Cannot invoke "org.springframework.test.web.servlet.ResultActions.andExpect(org.springframework.test.web.servlet.ResultMatcher)" because the return value of "org.springframework.test.web.servlet.MockMvc.perform(org.springframework.test.web.servlet.RequestBuilder)" is null

Here is my request method definition

@RequestMapping(value = "data/upload", method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA)
@CrossOrigin
@Loggable (activityname = ActivityLogConstants.CONFIG_DATA_UPLOAD, operationName =ActivityLogConstants.UPLOAD_OPERATIONNAME)
public Response importConfigData(HttpServletRequest request, @RequestParam("file") MultipartFile inFile, @RequestParam("rowData") String rowData) throws ServiceException {
....
}

I have HttpServletRequest,Multipartfile and String arguments to this method.

Here is my test

@ExtendWith(SpringExtension.class)
public class ConfigUploadTest {
@MockBean
private MockMvc mockMvc;


@InjectMocks
private UploadController uploadController;

@Test
public void vnfmService_ConfigUploadShouldReturnStatusOkTest() throws Exception {
    MockMultipartFile file = new MockMultipartFile(
            "file", // The request parameter name
            "test.xml", // The original filename (with .xml extension)
            "application/xml", // The content type for XML
            "<?xml version=\"1.0\" encoding=\"UTF-8\"?><data>This is some XML content</data>".getBytes());
    MockMultipartHttpServletRequestBuilder request = MockMvcRequestBuilders.multipart("/data/upload");
    request.file("file", file.getBytes());
    request.param("rowData","{"test":"test"}");
    mockMvc.perform(request).andExpect(status().isOk());
}
}

I don't want to load my entire application context and hence I'm using @ExtendWith(SpringExtension.class)

Please advise.

Answer 1

There appears to be a few errors.

First, you have used @MockBean on MockMvc. @MockBean creates a mock of an existing bean within your code. You want to have the actual instance of MockMvc so you need to autowire it using the @Autowired annotation.

This won’t work alone leading to the second point, you should be using @WebMvcTest which includes @ExtendsWith(SpringExtension.class) internally. This will setup MockMvc to work for your test with your code.

Third, you are using @InjectMocks with your controller. Since you are testing the http call, this is unnecessary and can be removed.

So with these changes, it should look something like this:

@WebMvcTest(UploadController.class)
public class ConfigUploadTest {
  @Autowired
  private MockMvc mockMvc;

  @Test

You should read the Spring Boot Reference Documentation for more information about how Spring tests work.