How to test http calls in Go using httptest

httptest does two types of tests: response and server

Response test:

func TestHeader3D(t *testing.T) {
    resp := httptest.NewRecorder()

    uri := "/3D/header/?"
    path := "/home/test"
    unlno := "997225821"

    param := make(url.Values)
    param["param1"] = []string{path}
    param["param2"] = []string{unlno}

    req, err := http.NewRequest("GET", uri+param.Encode(), nil)
    if err != nil {
            t.Fatal(err)
    }

    http.DefaultServeMux.ServeHTTP(resp, req)
    if p, err := ioutil.ReadAll(resp.Body); err != nil {
            t.Fail()
    } else {
            if strings.Contains(string(p), "Error") {
                    t.Errorf("header response shouldn't return error: %s", p)
            } else if !strings.Contains(string(p), `expected result`) {
                    t.Errorf("header response doen't match:\n%s", p)
            }
    }
}

Server test (which is what you need to use):

func TestIt(t *testing.T){
    ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        w.Header().Set("Content-Type", "application/json")
        fmt.Fprintln(w, `{"fake twitter json string"}`)
    }))
    defer ts.Close()

    twitterUrl = ts.URL
    c := make(chan *twitterResult)
    go retrieveTweets(c)

    tweet := <-c
    if tweet != expected1 {
        t.Fail()
    }
    tweet = <-c
    if tweet != expected2 {
        t.Fail()
    }
}

BTW, you don’t need to pass in the pointer of r, because it’s already a pointer.

err = json.Unmarshal(body, r)

EDIT: for my recorder test, I could use my http handler like this:

handler(resp, req)

But my original code is not using the default mux (but from Gorilla/mux), and I have some wrapping around the mux, e.g. insert server logging, and adding request context (Gorilla/context), so I had to start from mux and call ServeHTTP