feat: Implement ping/pong support

src/index.ts

@@ -1,6 +1,7 @@
 export { MockClient } from './lib/MockClient';
 export { MockPeer } from './lib/MockPeer';
 export { MockServer } from './lib/MockServer';
+export { PingOrPong } from './lib/PingOrPong';
 export * from './lib/MockServerAction';
 export { CloseFrame } from './lib/CloseFrame';
 export { createMockWebSocketStream } from './lib/stream';

src/lib/MockPeer.ts

@@ -3,6 +3,7 @@ import { Data as WSData } from 'ws';
 
 import { CloseFrame } from './CloseFrame';
 import { MockWebSocket } from './MockWebSocket';
+import { PingOrPong } from './PingOrPong';
 
 export abstract class MockPeer {
   protected readonly peerWebSocket = new MockWebSocket();
@@ -55,6 +56,42 @@ export abstract class MockPeer {
     return this.peerWebSocket.closeFrame;
   }
 
+  /**
+   * Send ping to peer and return ping data.
+   *
+   * @param data
+   */
+  public ping(data?: Buffer): Buffer {
+    const finalData = data ?? Buffer.from(Math.random().toString());
+    this.peerWebSocket.emit('ping', finalData);
+    return finalData;
+  }
+
+  /**
+   * Send pong to peer.
+   *
+   * @param data
+   */
+  public pong(data: Buffer): void {
+    this.peerWebSocket.emit('pong', data);
+  }
+
+  /**
+   * Return pings sent by peer.
+   */
+  get incomingPings(): readonly PingOrPong[] {
+    // Return a shallow copy to avoid race conditions if more pings are received
+    return [...this.peerWebSocket.outgoingPings];
+  }
+
+  /**
+   * Return pongs sent by peer.
+   */
+  get incomingPongs(): readonly PingOrPong[] {
+    // Return a shallow copy to avoid race conditions if more pings are received
+    return [...this.peerWebSocket.outgoingPongs];
+  }
+
   /**
    * Mimic the conversion that `ws` would do on binary frames.
    *

src/lib/MockWebSocket.ts

@@ -3,22 +3,48 @@ import { Duplex } from 'stream';
 import { Data as WSData } from 'ws';
 
 import { CloseFrame } from './CloseFrame';
+import { PingOrPong } from './PingOrPong';
 
 export class MockWebSocket extends EventEmitter {
   // tslint:disable-next-line:readonly-keyword
   public binaryType: 'nodebuffer' | 'arraybuffer' = 'nodebuffer';
 
+  // tslint:disable-next-line:readonly-array
+  public readonly outgoingPings: PingOrPong[] = [];
+  // tslint:disable-next-line:readonly-array
+  public readonly outgoingPongs: PingOrPong[] = [];
+
   // tslint:disable-next-line:readonly-keyword
   protected ownCloseFrame: CloseFrame | null = null;
   // tslint:disable-next-line:readonly-array
   protected readonly messagesSent: WSData[] = [];
   protected readonly ownEvents = new EventEmitter();
 
   public send(data: WSData): void {
+    this.requireOpenConnection();
+
     this.messagesSent.push(data);
     this.ownEvents.emit('messageSent', data);
   }
 
+  public ping(data?: WSData, mask?: boolean, cb?: (err?: Error) => void): void {
+    this.requireOpenConnection();
+
+    this.outgoingPings.push({ data, cb, mask, date: new Date() });
+    if (cb) {
+      cb();
+    }
+  }
+
+  public pong(data?: WSData, mask?: boolean, cb?: (err?: Error) => void): void {
+    this.requireOpenConnection();
+
+    this.outgoingPongs.push({ data, cb, mask, date: new Date() });
+    if (cb) {
+      cb();
+    }
+  }
+
   /**
    * @internal
    */
@@ -37,9 +63,7 @@ export class MockWebSocket extends EventEmitter {
   }
 
   public close(code?: number, reason?: string): void {
-    if (this.ownCloseFrame) {
-      throw new Error('Connection closure was already initiated');
-    }
+    this.requireOpenConnection();
 
     // tslint:disable-next-line:no-object-mutation
     this.ownCloseFrame = { code, reason };
@@ -89,6 +113,12 @@ export class MockWebSocket extends EventEmitter {
 
     return duplex;
   }
+
+  private requireOpenConnection(): void {
+    if (this.ownCloseFrame) {
+      throw new Error('Connection is not open (anymore)');
+    }
+  }
 }
 
 async function waitForEvent<T>(eventName: string, eventEmitter: EventEmitter): Promise<T> {

src/lib/PingOrPong.ts

@@ -0,0 +1,8 @@
+import { Data as WSData } from 'ws';
+
+export interface PingOrPong {
+  readonly data?: WSData;
+  readonly mask?: boolean;
+  readonly cb?: (err?: Error) => void;
+  readonly date: Date;
+}