server_test.go

func withTestServer(handler http.HandlerFunc, f func(*httptest.Server)) {
	server := httptest.NewServer(handler)
	defer server.Close()
	f(server)
}

func TestSomething(t *testing.T) {
	hf := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, r.URL.Path)
	})

	withTestServer(hf, func(server *httptest.Server) {
		resp := http.Get(server.URL)
		// ...
	})
}