func TestCancelAfterRequest(t *testing.T) {
    ctx, cancel := context.WithCancel(context.Background())

    resp, err := doRequest(ctx)

    // Cancel before reading the body.
    // Request.Body should still be readable after the context is canceled.
    cancel()

    b, err := ioutil.ReadAll(resp.Body)
    if err != nil || string(b) != requestBody {
        t.Fatalf("could not read body: %q %v", b, err)
    }
}

func TestCancelAfterRequest(t *testing.T) {
    var okHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        w.WriteHeader(http.StatusOK)
        <-w.(http.CloseNotifier).CloseNotify()
    })

    serv := httptest.NewServer(okHandler)
    defer serv.Close()

    ctx, cancel := context.WithCancel(context.Background())
    resp, err := Get(ctx, nil, serv.URL)

    cancel()

    var bs [1]byte
    n, err := resp.Body.Read(bs[:])
    log.Printf("n, err := %v, %v", n, err)
}