refactor: Refactor media loading manager for improved robustness (#2464)

tests/utils/abort-signal.test.ts

@@ -0,0 +1,39 @@
+import { describe, expect, it, vi } from 'vitest';
+import { onAbort } from '../../src/utils/abort-signal';
+
+describe('onAbort', () => {
+  it('should call the callback when the signal aborts', () => {
+    const ac = new AbortController();
+    const cb = vi.fn();
+    onAbort(ac.signal, cb);
+
+    expect(cb).not.toBeCalled();
+
+    ac.abort();
+    expect(cb).toBeCalledTimes(1);
+  });
+
+  it('should call the callback synchronously if the signal is already aborted', () => {
+    const ac = new AbortController();
+    ac.abort();
+
+    const cb = vi.fn();
+    onAbort(ac.signal, cb);
+
+    expect(cb).toBeCalledTimes(1);
+  });
+
+  it('should fire only once even if the signal aborts repeatedly', () => {
+    const ac = new AbortController();
+    const cb = vi.fn();
+    onAbort(ac.signal, cb);
+
+    ac.abort();
+    // Aborting an AbortController again is a no-op, but verify the listener
+    // is registered with `once: true` so any synthetic re-fire would be a
+    // no-op too.
+    ac.signal.dispatchEvent(new Event('abort'));
+
+    expect(cb).toBeCalledTimes(1);
+  });
+});