main.go

package main

import (
	"net/http"

	"github.com/gorilla/mux"
)

func main() {
	http.Handle("/", getRouter())
}

func getRouter() *mux.Router {
	r := mux.NewRouter()
	r.HandleFunc("/{name}", NameHandler)
	return r
}

func NameHandler(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	w.Write([]byte("Hello, " + vars["name"]))
}

main_test.go

package main

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

func TestNameHandler(t *testing.T) {
	r := getRouter()

	req, err := http.NewRequest("GET", "https://example.com/Paddy", nil)
	if err != nil {
		t.Fatal("Can't build request:", err)
	}
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Errorf("Expected response code to be %d, got %d", http.StatusOK, w.Code)
	}
	if w.Body.String() != "Hello, Paddy" {
		t.Errorf(`Expected response to be "%s", got "%s"`, "Hello, Paddy", w.Body.String())
	}
}