CODEWITHSUNDEEP
javascriptunit-testingmocha.jschaisinon
Eunito
Eunito

Reputation: 436

How to set timeout in a javascript unit test using sinon.useFakeTimers

I'm trying to test the following method:

endSocketConn(socket) {
    if(!socket) {
        return;
    }

    socket.setTimeout(5000, () => {
        socket.destroy();
    });

    socket.end('commandToSend');
}

The scenario I need to test is the one where if more than 5seconds are elapsed then socket.destroy() must be called one time

describe('Testing API | socketPool methods', async function () {

    beforeEach(async function () {
        let clock = sinon.useFakeTimers();
        let socketMock = {
            setTimeout: sinon.spy(),
            destroy: sinon.spy(),
            end: sinon.spy(), 
        };
    });

    afterEach(async function () {
        clock && clock.restore();
    });
    
    describe('Testing endSocketConn() function', function () {
        
        it('It should execute socket.destroy if timeout occurred after sending commandToSend', async function () {
            let result;
            let error = false;
            try {
                clock.tick(6000);
                result = await file.endSocketConn(socketMock);
            } catch (err) {
                error = err;
            }
            expect(error).to.be.false;
            sinon.assert.callCount(socketMock.setTimeout, 1);
            sinon.assert.callCount(socketMock.end, 1);
            
            sinon.assert.callCount(socketMock.destroy, 1); 
            // AssertError: expected spy to be called once but was called 0 times
        });
    });

Any idea why the timeout is not being properly simulated?

Upvotes: 0

Views: 1053

Answers (1)

Lin Du
Lin Du

Reputation: 102277

You don't need to use sinon.useFakeTimers(), because we can use the stub to implement a method that has nothing to do with the real setTimeout.

E.g.

file.js:

  endSocketConn(socket) {
    if (!socket) {
      return;
    }

    socket.setTimeout(5000, () => {
      socket.destroy();
    });

    socket.end('commandToSend');
  },
};

export { file };

file.test.js:

import sinon from 'sinon';
import { file } from './file';

describe('Testing API | EslSocketPoolHandler methods', function () {
  let socketMock;
  beforeEach(function () {
    socketMock = {
      setTimeout: sinon.stub(),
      destroy: sinon.spy(),
      end: sinon.spy(),
    };
  });

  describe('Testing endSocketConn() function', function () {
    it('It should execute socket.destroy if timeout occurred after sending commandToSend', function () {
      socketMock.setTimeout.callsFake((ms, cb) => {
        cb();
      });
      file.endSocketConn(socketMock);

      sinon.assert.callCount(socketMock.setTimeout, 1);
      sinon.assert.callCount(socketMock.end, 1);
      sinon.assert.callCount(socketMock.destroy, 1);
    });
  });
});

unit test result:

  Testing API | EslSocketPoolHandler methods
    Testing endSocketConn() function
      ✓ It should execute socket.destroy if timeout occurred after sending commandToSend


  1 passing (7ms)

----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |   85.71 |       50 |     100 |   85.71 |                   
 file.ts  |   85.71 |       50 |     100 |   85.71 | 4                 
----------|---------|----------|---------|---------|-------------------

Upvotes: 1

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