app.go

package main

import (
	"fmt"
	"net/http"
)

func HelloHandler(res http.ResponseWriter, req *http.Request) {
	res.WriteHeader(200)
	name := req.URL.Query().Get("name")
	if name == "" {
		name = "World"
	}
	fmt.Fprintf(res, "Hello, %s!", name)
}

func FormHandler(res http.ResponseWriter, req *http.Request) {
	err := req.ParseForm()
	if err != nil {
		res.WriteHeader(500)
		return
	}
	name := req.Form.Get("name")
	if name == "" {
		name = "World"
	}
	fmt.Fprintf(res, "Posted Hello, %s!", name)
}

type Responder struct {
	http.ResponseWriter
	status int
}

func (r *Responder) WriteHeader(i int) {
	r.status = i
	r.ResponseWriter.WriteHeader(i)
}

func App() http.Handler {
	mux := http.NewServeMux()
	mux.HandleFunc("/hello", HelloHandler) // GET
	mux.HandleFunc("/form", FormHandler)   // POST

	h := func(res http.ResponseWriter, req *http.Request) {
		rs := &Responder{ResponseWriter: res, status: 200}
		mux.ServeHTTP(rs, req)
		if rs.status == 500 {
			rs.Write([]byte("Oops!"))
		}
	}
	return http.HandlerFunc(h)
}

func main() {
	http.ListenAndServe(":3000", App())
}

app_integration_test.go

package main

import (
	"io/ioutil"
	"net/http"
	"net/http/httptest"
	"net/url"
	"strings"
	"testing"

	"github.com/stretchr/testify/require"
)

func Test_I_HelloHandler(t *testing.T) {
	r := require.New(t)

	ts := httptest.NewServer(App())
	defer ts.Close()

	res, err := http.Get(ts.URL + "/hello")
	r.NoError(err)

	r.Equal(200, res.StatusCode)
	b, err := ioutil.ReadAll(res.Body)
	r.NoError(err)
	r.Equal("Hello, World!", string(b))
}

func Test_I_HelloHandler_WithQuery(t *testing.T) {
	r := require.New(t)

	ts := httptest.NewServer(App())
	defer ts.Close()

	res, err := http.Get(ts.URL + "/hello?name=Ringo")
	r.NoError(err)

	r.Equal(200, res.StatusCode)
	b, err := ioutil.ReadAll(res.Body)
	r.NoError(err)
	r.Equal("Hello, Ringo!", string(b))
}

func Test_I_FormHandler(t *testing.T) {
	r := require.New(t)

	ts := httptest.NewServer(App())
	defer ts.Close()

	form := url.Values{}
	form.Add("name", "Ringo")

	res, err := http.PostForm(ts.URL+"/form", form)
	r.NoError(err)

	r.Equal(200, res.StatusCode)
	b, err := ioutil.ReadAll(res.Body)
	r.NoError(err)
	r.Equal("Posted Hello, Ringo!", string(b))
}

app_test.go

package main

import (
	"net/http/httptest"
	"net/url"
	"strings"
	"testing"

	"github.com/stretchr/testify/require"
)

func Test_U_HelloHandler(t *testing.T) {
	r := require.New(t)

	req := httptest.NewRequest("GET", "/hello", nil)
	res := httptest.NewRecorder()

	HelloHandler(res, req)

	r.Equal(200, res.Code)
	r.Equal("Hello, World!", res.Body.String())
}

func Test_U_HelloHandler_WithQuery(t *testing.T) {
	r := require.New(t)

	req := httptest.NewRequest("GET", "/hello?name=Ringo", nil)
	res := httptest.NewRecorder()

	HelloHandler(res, req)

	r.Equal(200, res.Code)
	r.Equal("Hello, Ringo!", res.Body.String())
}

func Test_U_FormHandler(t *testing.T) {
	r := require.New(t)

	form := url.Values{}
	form.Add("name", "Ringo")
	req := httptest.NewRequest("POST", "/form", strings.NewReader(form.Encode()))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	res := httptest.NewRecorder()

	FormHandler(res, req)
	r.Equal(200, res.Code)
	r.Equal("Posted Hello, Ringo!", res.Body.String())
}