Go言語とRESTful API: シンプルかつ効率的なWebサービスの構築

package main

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

type User struct {
	ID   string `json:"id"`
	Name string `json:"name"`
	Age  int    `json:"age"`
}

var users = []User{
	{"1", "John Doe", 25},
	{"2", "Jane Doe", 24},
}

func getUser(w http.ResponseWriter, r *http.Request) {
	json.NewEncoder(w).Encode(users)
}

func main() {
	http.HandleFunc("/users", getUser)
	http.ListenAndServe(":8080", nil)
}

//...
func getUser(w http.ResponseWriter, r *http.Request) {
	if r.Method == http.MethodGet {
		id := r.URL.Query().Get("id")
		for _, user := range users {
			if user.ID == id {
				json.NewEncoder(w).Encode(user)
				return
			}
		}
		w.WriteHeader(http.StatusNotFound)
	} else {
		w.WriteHeader(http.StatusMethodNotAllowed)
	}
}
//...

//...
import (
	"io/ioutil"
	//...
)

//...

func updateUser(w http.ResponseWriter, r *http.Request) {
	if r.Method == http.MethodPut {
		id := r.URL.Query().Get("id")
		for i, user := range users {
			if user.ID == id {
				body, err := ioutil.ReadAll(r.Body)
				if err != nil {
					w.WriteHeader(http.StatusInternalServerError)
					return
				}
				var updatedUser User
				err = json.Unmarshal(body, &updatedUser)
				if err != nil {
					w.WriteHeader(http.StatusBadRequest)
					return
				}
				users[i] = updatedUser
				json.NewEncoder(w).Encode(updatedUser)
				return
			}
		}
		w.WriteHeader(http.StatusNotFound)
	} else {
		w.WriteHeader(http.StatusMethodNotAllowed)
	}
}

func main() {
	http.HandleFunc("/users", getUser)
	http.HandleFunc("/users/update", updateUser)
	http.ListenAndServe(":8080", nil)
}

//...
import (
	"github.com/stretchr/testify/assert"
	"net/http/httptest"
	"strings"
	"testing"
)

func TestUpdateUser(t *testing.T) {
	request := httptest.NewRequest(http.MethodPut, "/users/update?id=1", strings.NewReader(`{"id":"1", "name":"John Smith", "age":30}`))
	responseRecorder := httptest.NewRecorder()

	updateUser(responseRecorder, request)

	assert.Equal(t, http.StatusOK, responseRecorder.Code)
	user := User{}
	err := json.NewDecoder(responseRecorder.Body).Decode(&user)
	assert.NoError(t, err)
	assert.Equal(t, "1", user.ID)
	assert.Equal(t, "John Smith", user.Name)
	assert.Equal(t, 30, user.Age)
}