How to Test HTTP Handlers in Go with httptest

Use net/http/httptest to create a mock server and client that execute your handler without starting a real network listener.

package main

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

func TestHandler(t *testing.T) {
	req := httptest.NewRequest("GET", "/", nil)
	rr := httptest.NewRecorder()
	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		w.Write([]byte("OK"))
	})
	handler.ServeHTTP(rr, req)

	if status := rr.Code; status != http.StatusOK {
		t.Errorf("handler returned wrong status code: got %v want %v", status, http.StatusOK)
	}
}

Testing HTTP Handlers in Go with httptest lets you verify web server logic by faking incoming requests and capturing responses in memory. This matters because it allows you to run tests instantly without needing a running server or network access. Think of it as a practice dummy for your code to punch instead of a real person.