websocket.test.js

test("Can receive broadcast connection", async (done) => {
  jest.setTimeout(500); // timeout quickly if done() isn't called.

  let postResult = null;
  // Need to set up message handler *before* making POST request.
  ws.addEventListener("message", async (event) => {
    try {
      // When message arrives, we know POST request was sent. So, verify its result.
      const resp = await postResult;
      expect(resp.status).toBe(200);

      const message = JSON.parse(event.data);
      expert(messasge).toBe(expectedMessage);
      done();
    } catch (err) {
      done(err);
    }
  });

  postResult = axios.post(
    `${config.APP_URL}/event`,
    broadcastMessage
  );
});