Allow overriding WebSocket implementation and add flaky version for testing

frontend/test-client/src/utils/flaky-websocket.ts

@@ -0,0 +1,61 @@
+import { sleep } from "./sleep";
+
+export function flakyWebSocketFactory(
+	jitterScaleInSeconds: number
+): typeof WebSocket {
+	// eslint-disable-next-line
+	return class FlakyWebSocket extends require("ws") {
+		public set onopen(callback: (event: Event) => void) {
+			// eslint-disable-next-line
+			super.onopen = async (event: Event): Promise<void> => {
+				if (jitterScaleInSeconds > 0) {
+					await sleep(Math.random() * jitterScaleInSeconds * 1000);
+				}
+
+				callback(event);
+			};
+		}
+
+		public set onmessage(callback: (event: MessageEvent) => void) {
+			// eslint-disable-next-line
+			super.onmessage = async (event: MessageEvent): Promise<void> => {
+				if (jitterScaleInSeconds > 0) {
+					await sleep(Math.random() * jitterScaleInSeconds * 1000);
+				}
+
+				callback(event);
+			};
+		}
+
+		public set onclose(callback: (event: CloseEvent) => void) {
+			// eslint-disable-next-line
+			super.onclose = async (event: CloseEvent): Promise<void> => {
+				if (jitterScaleInSeconds > 0) {
+					await sleep(Math.random() * jitterScaleInSeconds * 1000);
+				}
+				callback(event);
+			};
+		}
+
+		public set onerror(callback: (event: Event) => void) {
+			// eslint-disable-next-line
+			super.onerror = async (event: Event): Promise<void> => {
+				if (jitterScaleInSeconds > 0) {
+					await sleep(Math.random() * jitterScaleInSeconds * 1000);
+				}
+				callback(event);
+			};
+		}
+
+		public async send(
+			data: string | ArrayBufferLike | Blob | ArrayBufferView
+		): Promise<void> {
+			if (jitterScaleInSeconds > 0) {
+				await sleep(Math.random() * jitterScaleInSeconds * 1000);
+			}
+
+			// eslint-disable-next-line
+			super.send(data);
+		}
+	} as unknown as typeof WebSocket;
+}