valid_test.go

package main

import "testing"

func Test_isValid(t *testing.T) {
	f := func(URL, clientSecret string, want, wantErr bool) {
		t.Helper()
		got, err := isValid(URL, clientSecret)
		if (err != nil) != wantErr {
			t.Errorf("isValid() error = %v, wantErr %v", err, wantErr)
			return
		}
		if got != want {
			t.Errorf("isValid() = %v, want %v", got, want)
		}
	}
	f("http://[%10::1]", "", false, true)
	f("https://example.com", "", false, true)
	f("https://example.com?sign=abc", "", false, false)
	f("https://example.com?q=abc", "", false, false)
	f("https://example.com?sign=abc&%gh&%ij", "", false, true)

	f(
		"https://example.com/?vk_user_id=494075&vk_app_id=6736218&vk_is_app_user=1&vk_are_notifications_enabled=1&vk_language=ru&vk_access_token_settings=notify&vk_platform=android&sign=exTIBPYTrAKDTHLLm2AwJkmcVcvFCzQUNyoa6wAjvW6k",
		"wvl68m4dR1UpLrVRli",
		false,
		false,
	)
	f(
		"https://example.com/?vk_user_id=494075&vk_app_id=6736218&vk_is_app_user=1&vk_are_notifications_enabled=1&vk_language=ru&vk_access_token_settings=&vk_platform=android&sign=htQFduJpLxz7ribXRZpDFUH-XEUhC9rBPTJkjUFEkRA",
		"wvl68m4dR1UpLrVRli",
		true,
		false,
	)
}

@SenchoPens тут можно посмотреть

@SevereCloud спасибо!