HTTP server shutdown example

server_test.go

package server

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"testing"
	"time"

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

func TestShutdown(t *testing.T) {
	server := http.Server{
		Addr: ":8080",
		Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			fmt.Println("handler: request is made")
			select {
			case <-r.Context().Done():
				fmt.Println("handler: context is done")
			case <-time.After(time.Second * 5):
				fmt.Println("handler: long operation is done")
			}
		}),
	}

	go server.ListenAndServe()

	go func() {
		var reader io.Reader = slowReader(5 * time.Second)
		timeout := 30 * time.Second
		if false {
			// ^ make it true if you want to test the client connection closed
			timeout = time.Second
			reader = nil
		}

		client := http.Client{
			Transport:     nil,
			CheckRedirect: nil,
			Jar:           nil,
			Timeout:       timeout,
		}
		fmt.Println("client: making http request")
		_, err := client.Post("http://localhost:8080", "", reader)
		assert.NoError(t, err)
		fmt.Println("client: http request is done")
	}()

	time.Sleep(2 * time.Second)
	fmt.Println("starting server shutdown")
	err := server.Shutdown(context.Background())
	assert.NoError(t, err)
	// to wait output from all goroutines
	time.Sleep(time.Second)
}

type slowReader time.Duration

func (sr slowReader) Read(_ []byte) (int, error) {
	time.Sleep(time.Duration(sr))
	return 0, nil
}