How to PUT multipart/form-data using Spring MockMvc?

Yes, there is a way, and it's simple too!

I ran into the same problem myself. Though I was discouraged by Sam Brannen's answer, it appears that Spring MVC nowadays DOES support PUT file uploading as I could simply do such a request using Postman (I'm using Spring Boot 1.4.2). So, I kept digging and found that the only problem is the fact that the MockMultipartHttpServletRequestBuilder returned by MockMvcRequestBuilders.fileUpload() has the method hardcoded to "POST". Then I discovered the with() method...

and that allowed me to come up with this neat little trick to force the MockMultipartHttpServletRequestBuilder to use the "PUT" method anyway:

    MockMultipartFile file = new MockMultipartFile("data", "dummy.csv",
            "text/plain", "Some dataset...".getBytes());

    MockMultipartHttpServletRequestBuilder builder =
            MockMvcRequestBuilders.multipart("/test1/datasets/set1");
    builder.with(new RequestPostProcessor() {
        @Override
        public MockHttpServletRequest postProcessRequest(MockHttpServletRequest request) {
            request.setMethod("PUT");
            return request;
        }
    });
    mvc.perform(builder
            .file(file))
            .andExpect(status().isOk());

  Works like a charm!

This is unfortunately currently not supported in Spring MVC Test, and I don't see a work-around other than creating your own custom MockPutMultipartHttpServletRequestBuilder and copying-n-pasting code from the standard implementation.

For what it's worth, Spring MVC also does not support PUT requests for file uploads by default either. The Multipart resolvers are hard coded to accept only POST requests for file uploads -- both for Apache Commons and the standard Servlet API support.

If you would like Spring to support PUT requests in addition, feel free to open a ticket in Spring's JIRA issue tracker.

Translating @HammerNl answer for Kotlin. This worked for me.

val file = File("/path/to/file").readBytes()
val multipartFile = MockMultipartFile("image", "image.jpg", "image/jpg", file)

val postProcess = RequestPostProcessor { it.method = "PUT"; it}
mockMvc.perform(
    MockMvcRequestBuilders.multipart("/api/image/$id")
        .file(multipartFile)
        .with(postProcess))
        .andExpect(MockMvcResultMatchers.status().isOk)