Golearnings: HTTP Requests

golearnings_http_req_1.go

func GetThings() {
	res, err := http.Get("https://httpbin.org/get")
	if err != nil {
		log.Fatalln(err)
	}

	body, err := ioutil.ReadAll(res.Body)
	if err != nil {
		log.Fatalln(err)
	}

	log.Println(string(body))
}

golearnings_http_req_2.go

func GetThings() {
	const GetTimeout = 5

	req, err := http.NewRequest(http.MethodGet, "https://httpbin.org/get", nil)
	if err != nil {
		log.Fatalln(err)
	}

	client := http.Client{
		Timeout: GetTimeout * time.Second,
	}
	res, err := client.Do(req)
	if err != nil {
		log.Fatalln(err)
	}
	defer res.Body.Close()

	body, err := ioutil.ReadAll(res.Body)
	if err != nil {
		log.Fatalln(err)
	}

	log.Println(string(body))
}

golearnings_http_req_3.go

req, err := http.NewRequest(http.MethodGet, "https://httpbin.org/get", nil)
if err != nil {
	log.Fatalln(err)
}

req.Header.Set("Content-Type", "application/json; charset=utf-8")

golearnings_http_req_4.go

res, err := client.Do(req)
if err != nil {
	log.Fatalln(err)
}
defer res.Body.Close()

golearnings_http_req_5.go

type BinSlideshow struct {
	Slideshow struct {
		Author string `json:"author"`
		Title  string `json:"title"`
		Slides []struct {
			Title string `json:"title"`
		} `json:"slides"`
	} `json:"slideshow"`
}

func GetSlideshow() (*BinSlideshow, error) {
	const GetTimeout = 5

	req, err := http.NewRequest(http.MethodGet, "https://httpbin.org/json", nil)
	if err != nil {
		return nil, err
	}

	client := http.Client{
		Timeout: GetTimeout * time.Second,
	}
	res, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	defer res.Body.Close()

	slideshow := &BinSlideshow{}
	decoder := json.NewDecoder(res.Body)

	err = decoder.Decode(&slideshow)
	if err != nil {
		return nil, err
	}

	return slideshow, nil
}

golearnings_http_req_6.go

func DownloadSlideshow() error {
	const GetTimeout = 5

	req, err := http.NewRequest(http.MethodGet, "https://httpbin.org/json", nil)
	if err != nil {
		return err
	}

	client := http.Client{
		Timeout: GetTimeout * time.Second,
	}
	res, err := client.Do(req)
	if err != nil {
		return err
	}
	defer res.Body.Close()

	out, err := os.Create("res.json")
	if err != nil {
		return err
	}
	defer out.Close()

	_, err = io.Copy(out, res.Body)
	return err
}

golearnings_http_req_7.go

package main

import (
	"encoding/json"
	"net/http"
)

type HTTPClient interface {
	Do(req *http.Request) (*http.Response, error)
}

type Application struct {
	httpClient HTTPClient
}

type BinSlideshow struct {
	Slideshow struct {
		Author string `json:"author"`
		Title  string `json:"title"`
		Slides []struct {
			Title string `json:"title"`
		} `json:"slides"`
	} `json:"slideshow"`
}

func (a *Application) GetSlideshow() (*BinSlideshow, error) {
	const GetTimeout = 5

	req, err := http.NewRequest(http.MethodGet, "https://httpbin.org/json", nil)
	if err != nil {
		return nil, err
	}

	res, err := a.httpClient.Do(req)
	if err != nil {
		return nil, err
	}
	defer res.Body.Close()

	slideshow := &BinSlideshow{}
	decoder := json.NewDecoder(res.Body)

	err = decoder.Decode(&slideshow)
	if err != nil {
		return nil, err
	}

	return slideshow, nil
}

golearnings_http_req_8.go

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"testing"
)

type mockClient struct {
	StubDo func(req *http.Request) (*http.Response, error)
}

func (m *mockClient) Do(req *http.Request) (*http.Response, error) {
	return m.StubDo(req)
}

func TestGetSlideshow(t *testing.T) {
	client := &mockClient{}
	app := &Application{
		httpClient: client,
	}

	t.Run("Expect error when httpbin is down", func(t *testing.T) {
		client.StubDo = func(req *http.Request) (*http.Response, error) {
			return &http.Response{
				StatusCode: http.StatusInternalServerError,
				Body:       ioutil.NopCloser(bytes.NewReader([]byte{})),
			}, nil
		}
		_, err := app.GetSlideshow()

		if err == nil {
			t.Error("Expected error on GetSlideshow")
		}
	})

	t.Run("Expect to get slideshow from httpbin", func(t *testing.T) {
		body := BinSlideshow{}
		bodyJson, _ := json.Marshal(body)

		client.StubDo = func(req *http.Request) (*http.Response, error) {
			return &http.Response{
				StatusCode: http.StatusOK,
				Body:       ioutil.NopCloser(bytes.NewReader(bodyJson)),
			}, nil
		}
		_, err := app.GetSlideshow()

		if err != nil {
			fmt.Println(err)
			t.Error("Unexpected error on GetSlideshow")
		}
	})
}