如何在 Golang 中测试 Web API？

import (
  "bytes"
  "net/http"
  "net/http/httptest"
  "testing"
)

func TestHandler(t *testing.T) {
  rr := httptest.NewRecorder()
  req, err := http.NewRequest("GET", "/api/v1/users", nil)
  if err != nil {
    t.Fatal(err)
  }
  
  // 这里调用要测试的实际函数的代码
}

if rr.Code != http.StatusOK {
  t.Errorf("状态代码错误：获取 %d，期望 %d", rr.Code, http.StatusOK)
}

func TestGetUser(t *testing.T) {
  user := User{ID: 1, Name: "John"}
  jsonBytes, err := json.Marshal(user)
  if err != nil {
    t.Fatal(err)
  }
  
  rr := httptest.NewRecorder()
  req, err := http.NewRequest("GET", "/api/v1/users/1", bytes.NewReader(jsonBytes))
  if err != nil {
    t.Fatal(err)
  }
  getUserHandler(rr, req)
  
  if rr.Code != http.StatusOK {
    t.Errorf("状态代码错误：获取 %d，期望 %d", rr.Code, http.StatusOK)
  }
  
  var returnedUser User
  err = json.Unmarshal(rr.Body.Bytes(), &returnedUser)
  if err != nil {
    t.Fatal(err)
  }
  
  if returnedUser != user {
    t.Errorf("返回的用户不正确：获取 %v，期望 %v", returnedUser, user)
  }
}