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Martin Hope
Gepser Hoil
Asked: 2020-03-09 09:00:37 +0800 CST
  • 4

I am doing unit tests on Goand according to some examples a test function is defined like this:

func TestAlgo(t *testing.T) {
    ...
}

What I want to know is what exactly does the parameter of that function mean?

I've also seen them do something like:

func TestAlgo(*testing.B) {
    ...
}

What is the difference with the previous parameter?

go
Martin Hope
Flimzy
Asked: 2020-01-05 12:48:50 +0800 CST
  • 4

I am reading the code of a package , and I see the following:

// Make sure the Router conforms with the http.Handler interface
var _ http.Handler = New()

What does that do?

It looks like it calls New(), which returns the type of http.Handler, but the result is discarded... Why do that?

go
Martin Hope
Flimzy
Asked: 2020-12-11 00:16:33 +0800 CST
  • 5

I've read about variadic functions :

The final parameter in a function signature may have a type prefixed with .... A function with such a parameter is called variadic and may be invoked with zero or more arguments for that parameter.

Translated:

The final parameter in a function signature can have a type prefixed with .... A function with such a parameter is called a variadic and can be called with zero or more arguments to that parameter.

So, it is valid:

func Zoológico(ación string, animales ...string) {
   // ...
}

But what will be the type of animales? Is it a string, or []string, or something else "special"?

go
Martin Hope
Flimzy
Asked: 2020-12-08 12:04:00 +0800 CST
  • 11

I have a very simple web server in Go, and on one page there is a form to upload a file:

<form method="post" action="/upload" enctype="multipart/form-data">
    <input type="file" name="image" accept="image/*"><br>
    Description: <input type="text" name="descr"><br>
    <input type="submit">
</form>

And I read the file in Go like this:

func imageUpload(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
    _,imageHead,err := r.FormFile("image")
    if err != nil {
        log.Printf("Error with upload: %s", err)
        return
    }
    imageDesc := r.FormValue("descr")

    fileSize := .... ???

    log.Printf("Recibí %s <%s> (%d bytes)", imageHead.Filename, imageDesc, fileSize)
}

But what do I do to get fileSize?

imageDatais a multipart.File , which exposes io.Reader, io.ReaderAt, io.Seeker and io.Closer . But don't file directly? So the only option is to read the io.Reader to see how many bytes I have? Or is there another more efficient option?

go