How to test an HTTP function which takes folder as an input? - unit-testing

Question

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
}

Answer 1

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)