Integration testing a node.js socket.io server

Check out this boilerplate solution that's based on promises and good practice. You can test your servers entire io events with it, no sweat. You just need to copy a boilerplate test and add your own code as needed.

Checkout the repo on GitHub for full source code.

https://github.com/PatMan10/testing_socketIO_server

const io = require("socket.io-client");
const ev = require("../utils/events");
const logger = require("../utils/logger");

// initSocket returns a promise
// success: resolve a new socket object
// fail: reject a error
const initSocket = () => {
  return new Promise((resolve, reject) => {
    // create socket for communication
    const socket = io("localhost:5000", {
      "reconnection delay": 0,
      "reopen delay": 0,
      "force new connection": true
    });

    // define event handler for sucessfull connection
    socket.on(ev.CONNECT, () => {
      logger.info("connected");
      resolve(socket);
    });

    // if connection takes longer than 5 seconds throw error
    setTimeout(() => {
      reject(new Error("Failed to connect wihtin 5 seconds."));
    }, 5000);
  });
};

// destroySocket returns a promise
// success: resolve true
// fail: reject false
const destroySocket = socket => {
  return new Promise((resolve, reject) => {
    // check if socket connected
    if (socket.connected) {
      // disconnect socket
      logger.info("disconnecting...");
      socket.disconnect();
      resolve(true);
    } else {
      // not connected
      logger.info("no connection to break...");
      resolve(false);
    }
  });
};

describe("test suit: Echo & Bello", () => {
  test("test: ECHO", async () => {
    try {
      // create socket for communication
      const socketClient = await initSocket();

      // create new promise for server response
      const serverResponse = new Promise((resolve, reject) => {
        // define a handler for the test event
        socketClient.on(ev.res_ECHO, data4Client => {
          //process data received from server
          const { message } = data4Client;
          logger.info("Server says: " + message);

          // destroy socket after server responds
          destroySocket(socketClient);

          // return data for testing
          resolve(data4Client);
        });

        // if response takes longer than 5 seconds throw error
        setTimeout(() => {
          reject(new Error("Failed to get reponse, connection timed out..."));
        }, 5000);
      });

      // define data 4 server
      const data4Server = { message: "CLIENT ECHO" };

      // emit event with data to server
      logger.info("Emitting ECHO event");
      socketClient.emit(ev.com_ECHO, data4Server);

      // wait for server to respond
      const { status, message } = await serverResponse;
      expect(status).toBe(200);
      expect(message).toBe("SERVER ECHO");
    } catch (error) {
      logger.error(error);
    }
  });

  test("test BELLO", async () => {
    try {
      const socketClient = await initSocket();
      const serverResponse = new Promise((resolve, reject) => {
        socketClient.on(ev.res_BELLO, data4Client => {
          const { message } = data4Client;
          logger.info("Server says: " + message);
          destroySocket(socketClient);
          resolve(data4Client);
        });

        setTimeout(() => {
          reject(new Error("Failed to get reponse, connection timed out..."));
        }, 5000);
      });

      const data4Server = { message: "CLIENT BELLO" };
      logger.info("Emitting BELLO event");
      socketClient.emit(ev.com_BELLO, data4Server);

      const { status, message } = await serverResponse;
      expect(status).toBe(200);
      expect(message).toBe("SERVER BELLO");
    } catch (error) {
      logger.error(error);
    }
  });
});