test: add episode title parsing test

static/player/episodes/titles.test.ts

@@ -0,0 +1,23 @@
+import assert from "node:assert/strict";
+import { before, test } from "node:test";
+
+before(() => {
+  Object.assign(globalThis, {
+    document: {
+      createElement: () => ({ classList: { add: () => undefined, remove: () => undefined } }),
+    },
+  });
+});
+
+test("parses only valid episode titles", async () => {
+  const { parseEpisodeTitles } = await import("./titles");
+  assert.deepEqual(
+    parseEpisodeTitles([
+      { number: 1, title: " First title " },
+      { number: 0, title: "Invalid" },
+      { number: 2, title: "" },
+      null,
+    ]),
+    [{ number: 1, title: "First title" }],
+  );
+});