Handle POST with Empty Body, Send 422

curl io

## not specifying a body
$ curl -i -XPOST localhost:50010
HTTP/1.1 422 Unprocessable Entity
Content-Type: text/plain; charset=utf-8
X-Content-Type-Options: nosniff
Date: Mon, 24 Dec 2018 12:34:11 GMT
Content-Length: 21

Unprocessable Entity

## specifiying an empty body
$ curl -i -XPOST localhost:50010 -d ''
HTTP/1.1 422 Unprocessable Entity
Content-Type: text/plain; charset=utf-8
X-Content-Type-Options: nosniff
Date: Mon, 24 Dec 2018 12:34:21 GMT
Content-Length: 21

Unprocessable Entity

go test -v

$ go test -v
=== RUN   TestBody
=== RUN   TestBody/Send_POST_with_empty_body,_expect_422
--- PASS: TestBody (0.00s)
    --- PASS: TestBody/Send_POST_with_empty_body,_expect_422 (0.00s)
PASS
ok  	examples/requestBody	0.002s

main.go

package main

import (
	"fmt"
	"log"
	"net/http"
)

func main() {
	server := NewServer()

	log.Println("starting server...")

	addr := fmt.Sprintf(":%s", "50010")

	log.Printf("server started 0.0.0.0%s\n", addr)
	if err := http.ListenAndServe(addr, server); err != nil {
		log.Fatalf("could not listen on %s, %v\n", addr, err)
	}
}

server.go

package main

import (
	"io/ioutil"
	"net/http"

	"github.com/gorilla/mux"
)

type Server struct {
	http.Handler
}

func handleBody(w http.ResponseWriter, r *http.Request) {
	body, err := ioutil.ReadAll(r.Body)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}

	if len(body) == 0 {
		http.Error(w, http.StatusText(http.StatusUnprocessableEntity),
			http.StatusUnprocessableEntity)
	}
}

func NewServer() *Server {
	router := mux.NewRouter()

	router.Handle("/", http.HandlerFunc(handleBody)).Methods("POST")

	server := Server{}

	server.Handler = router

	return &server
}

server_test.go

package main

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

var (
	emptyBody = []byte(``)
)

func TestBody(t *testing.T) {
	server := NewServer()

	t.Run("Send POST with empty body, expect 422", func(t *testing.T) {
		request := newRequest(t, http.MethodPost, "/", bytes.NewBuffer(emptyBody))
		response := httptest.NewRecorder()

		server.ServeHTTP(response, request)

		got := response.Code

		assertResponseStatus(t, got, http.StatusUnprocessableEntity)

	})
}

func newRequest(t *testing.T, method, path string, r io.Reader) (req *http.Request) {
	req, err := http.NewRequest(method, path, r)
	if err != nil {
		t.Fatalf("Failed to create new request: %v", err)
	}
	return
}

func assertResponseStatus(t *testing.T, got, expected int) {
	if got != expected {
		t.Errorf("wrong status code: got %v :: want %v", got, expected)
	}
}