test: add unit tests for pusher-js CJS export compat shim

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: Shaharshaki2

src/services/__tests__/client-channel-service.test.ts

@@ -0,0 +1,37 @@
+// eslint-disable-next-line node/no-extraneous-import,n/no-extraneous-import
+import { describe, expect, it } from '@jest/globals';
+
+/**
+ * Tests for the pusher-js CJS export compat shim in client-channel-service.
+ *
+ * pusher-js@8.5.0 changed its webpack build so the CJS export shape became:
+ *   module.exports.Pusher = PusherClass   (8.5.0+)
+ * instead of the previous:
+ *   module.exports = PusherClass          (< 8.5.0)
+ *
+ * The shim: `(pusherLib as { Pusher?: T }).Pusher ?? pusherLib`
+ * must resolve to the constructor in both cases.
+ */
+describe('Pusher import compat shim', () => {
+  it('resolves to the constructor when pusher-js exports it directly (< 8.5.0)', () => {
+    class FakePusher {}
+
+    type PusherConstructor = typeof FakePusher;
+    const pusherLib = FakePusher as unknown as PusherConstructor;
+    const Pusher = (pusherLib as unknown as { Pusher?: PusherConstructor }).Pusher ?? pusherLib;
+
+    expect(Pusher).toBe(FakePusher);
+    expect(new Pusher()).toBeInstanceOf(FakePusher);
+  });
+
+  it('resolves to the constructor when pusher-js wraps it in an object (>= 8.5.0)', () => {
+    class FakePusher {}
+
+    type PusherConstructor = typeof FakePusher;
+    const pusherLib = { Pusher: FakePusher } as unknown as PusherConstructor;
+    const Pusher = (pusherLib as unknown as { Pusher?: PusherConstructor }).Pusher ?? pusherLib;
+
+    expect(Pusher).toBe(FakePusher);
+    expect(new Pusher()).toBeInstanceOf(FakePusher);
+  });
+});