如何测试以文件夹为输入的HTTP函数？

I have an HTTP handler function (POST) which allows a user to upload a folder from a web browser application. The folder is passed from JavaScript code as an array of files in a folder and on the backend (Go API) it is accepted as a []*multipart.FileHeader. I am struggling in writing a Go unit test for this function. How can I pass a folder as input from a test function? I need help in creating the httpRequest in the right format.

I have tried to use / set values for an array of FileHeader, but some attributes are not allowed to be imported. So there must be a different way of testing this handler that I am not aware of.

Handler Function for folder upload:

func FolderUpload(w http.ResponseWriter, r *http.Request, p httprouter.Params) { 
// SOME LOGIC

files := r.MultipartForm.File["multiplefiles"] // files is of the type []*multipart.FileHeader

// SOME LOGIC TO PARSE THE FILE NAMES TO RECREATE THE SAME TREE STRUCTURE ON THE SERVER-SIDE AND STORE THEM AS A FOLDER

Unit Test function for the same handler:

func TestFolderUpload(t *testing.T) {
//     FolderPreCondition()
     request, err := http.NewRequest("POST", uri, body) //Q: HOW TO CREATE THE BODY ACCEPTABLE BY THE ABOVE HANDLER FUNC?
//     SOME ASSERTION LOGIC
}

You should write your file to request:

func newFileUploadRequest(url string, paramName, path string) (*http.Request, error) {
file, err := os.Open(path)

if err != nil {
    return nil, err
}

defer file.Close()

body := new(bytes.Buffer)

writer := multipart.NewWriter(body)

part, err := writer.CreateFormFile(paramName, filepath.Base(path))

if err != nil {
    return nil, err
}

_, err = io.Copy(part, file)

if err != nil {
    return nil, err
}

err = writer.Close()
if err != nil {
    return nil, err
}
req, err := http.NewRequest("POST", url, body)

if err != nil {
    return nil, err
}

req.Header.Add("Content-Type", writer.FormDataContentType())

return req, err

}

then use it:

    req, err := newFileUploadRequest("http://localhost:1234/upload", "multiplefiles", path)

client := &http.Client{}

resp, err := client.Do(req)

It works for me, hope it helps you)