也许像这样的东西？

@Autowired
    private MockMvc mockMvc;

    @Test
    public void parseMultipartFile_Should_Return_Ok() throws Exception {

        final MockPart file = new MockPart("file", new ClassPathResource("test.file").getInputStream().readAllBytes());
        file.getHeaders().set(CONTENT_TYPE, "application/octet-stream");

        final MockPart jsonData = new MockPart("info", "{\"some\": \"data\"}".getBytes());
        jsonData.getHeaders().set(CONTENT_TYPE, "application/json");

        mockMvc.perform(MockMvcRequestBuilders.multipart("/upload")
                .part(jsonData, file))
                .andExpect(status().isOk());
    }