Class FakeWebSocket

packages/socketio-shim/test/adapter.test.ts:12–43

A minimal fake WS that records outbound frames and routes event listeners.

/** A minimal fake WS that records outbound frames and routes event listeners. */
class FakeWebSocket implements WebSocketLike {
  readonly sent: string[] = [];
  closed: { code: number | undefined; reason: string | undefined } | null = null;
  private readonly listeners = new Map<string, Array<(ev: any) => void>>();
  sendThrows = false;
  closeThrows = false;

  send(data: string): void {
    if (this.sendThrows) throw new Error('boom');
    this.sent.push(data);
  }

  close(code?: number, reason?: string): void {
    if (this.closeThrows) throw new Error('close-boom');
    this.closed = { code, reason };
  }

  addEventListener(
    type: 'message' | 'close' | 'error',
    listener: (ev: any) => void,
  ): void {
    const bucket = this.listeners.get(type) ?? [];
    bucket.push(listener);
    this.listeners.set(type, bucket);
  }

  /** Drive inbound events from the test side. */
  emit(type: 'message' | 'close' | 'error', ev: any): void {
    const bucket = this.listeners.get(type) ?? [];
    for (const l of bucket) l(ev);
  }
}

/** A fake timer harness — caller can advance ticks deterministically. */
function makeFakeTimerHarness(): {