add test folder

test/utils.ts

@@ -0,0 +1,9 @@
+import { assertEquals } from "https://deno.land/std@0.177.0/testing/asserts.ts";
+
+import { parseYoutubeId } from "../utils.ts";
+
+Deno.test("parseYoutubeId", () => {
+  const url = parseYoutubeId("https://www.youtube.com/watch?v=ylAF0WNvLx0");
+
+  assertEquals(url, "ylAF0WNvLx0");
+});