Test Golang API Client Using httptest Package

gists.go

package gists

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

type Api struct {
	client  *http.Client
	headers map[string]string
	BaseURL string
}

type Gist struct {
	Id  string `json:"id,omitempty"`
	Url string `json:"url,omitempty"`
}

func NewApi() *Api {
	return &Api{
		client:  &http.Client{},
		headers: map[string]string{"Accept": "application/vnd.github.v3+json"},
		BaseURL: "https://api.github.com",
	}
}

func (api *Api) GetUserGists(username string) ([]Gist, error) {
	request, err := http.NewRequest("GET", fmt.Sprintf("%s/users/%s/gists", api.BaseURL, username), nil)
	if err != nil {
		return []Gist{}, err
	}

	for k, v := range api.headers {
		request.Header.Set(k, v)
	}

	response, err := api.client.Do(request)
	if err != nil {
		return []Gist{}, err
	}

	defer response.Body.Close()

	gists := []Gist{}
	err = json.NewDecoder(response.Body).Decode(&gists)
	if err != nil {
		return []Gist{}, err
	}

	return gists, nil
}

gists_test.go

package gists

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

func TestGetUserRepos(t *testing.T) {
	id := "repo1"
	url := "http://gists.github.com/repo1"

	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		w.Write([]byte(`[{"id":"` + id + `","url":"` + url + `"}]`))
	})

	client := httptest.NewServer(handler)

	api := NewApi()
	api.BaseURL = client.URL

	gists, _ := api.GetUserGists("foobar")
	if len(gists) != 1 {
		t.Error("returned more than one gist")
	}

	if gists[0].Id != id {
		t.Errorf("gist.Id is not %s", id)
	}

	if gists[0].Url != url {
		t.Errorf("gist.Url is not %s", url)
	}
}

main.go

package main

import (
	"fmt"
	"log"

	"github.com/ziadoz/gists/http-client-testing/pkg/gists"
)

func main() {
	gists, err := gists.NewApi().GetUserGists("ziadoz")
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%+v", gists)
}