Add a Websocket example

k6/foundations/13.basic.websockets.js

@@ -0,0 +1,64 @@
+import { sleep } from 'k6';
+import { WebSocket } from 'k6/experimental/websockets';
+import { setInterval } from 'k6/experimental/timers';
+import { Counter } from "k6/metrics";
+
+let BASE_URL = __ENV.BASE_URL || 'http://localhost:3333';
+
+BASE_URL = BASE_URL.replace("https://", "wss://");
+BASE_URL = BASE_URL.replace("http://", "ws://");
+
+export const options = {
+  scenarios: {
+    receiver: {
+      exec: "receiver",
+      executor: "ramping-vus",
+      executor: 'shared-iterations',
+      iterations: 1,
+      maxDuration: '1m',
+    },
+    sender: {
+      exec: "sender",
+      executor: 'shared-iterations',
+      iterations: 20,
+      vus: 10,
+
+      // delay the start to get the receiver ready
+      startTime: '2s',
+    },
+
+  }
+};
+
+// send two WS messages
+export function sender() {
+    const ws = new WebSocket(`${BASE_URL}/ws`);
+    ws.addEventListener('open', () => {
+        ws.send(JSON.stringify({ user: `VU ${__VU}`, msg: "order_pizza" }));
+        sleep(0.2);
+        ws.send(JSON.stringify({ user: `VU ${__VU}`, msg: "pizza_status?" }));
+        sleep(0.1);
+        ws.close();
+    });
+}
+
+export function receiver () {
+
+  // Close the WS connection to end the iteration once the number of expected messages is received.
+
+  // Be aware that a local counter (`messageCounter`) is valid here because only one `receiver` iteration runs.
+  let messageCounter = 0;
+  const totalExpectedMessages = 20*2; // 20 iterations * 2 messages per iteration
+
+  const ws = new WebSocket(`${BASE_URL}/ws`);
+  ws.addEventListener('open', () => {
+    ws.addEventListener('message', (e) => {
+      const msg = JSON.parse(e.data);
+      console.log(`VU ${__VU} received: ${msg.user} msg: ${msg.msg}`);
+      messageCounter++;
+      if (messageCounter === totalExpectedMessages) {
+        ws.close();
+      }
+    });
+  });
+}